Talk:Tilt–shift photography

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Link to Scheimpflug principle?[edit]

Either in the main body or as a footnote, there ought to be a cross reference to the Scheimpflug principle.

link to perspective correction lens?[edit]

The article Perspective correction lens explains this with images. Link/redirect there? 12:07, 4 December 2006 (UTC)

Merge with Perspective correction lens and View_camera#View_camera_movements[edit]

A far more comprehensive article is in place for the same topic, and camera movements are not restricted to tilt/shift and thus a bad name for this topic. --antilivedT | C | G 07:26, 9 January 2007 (UTC)

Text confuses lens tilt and rear standard tilt.[edit]

The text on this page also seems to confuse perspective correction (tilt of the rear standard) and control of the focal plane (tilt of the lens). Work needs to be done before it is merged into any other page.

Dennison Betram[edit]

The text doesn't say who Dennison Betram is or why his advice is notable. The Storm Surfer 00:01, 28 April 2007 (UTC)

He is notable because "It is also possible to construct a tilt-shift lens of sorts, as described in the linked article by Dennison Bertram." but I cannot find the link. Kwenchin (talk) 22:41, 28 February 2010 (UTC)

Twenty-first century[edit]

"This was popular in the early years of the twenty-first century."

That sounds odd. Last time I checked, we were still in the early years of the twenty-first century... Arnaudf 19:50, 30 April 2007 (UTC)

Now that you mention the sentence, I wonder if the source even makes the claim. It doesn't look to me like it does, but I don't have time to read it all in detail. Could someone please either provide a quotation or confirm that there isn't one that could be provided and remove the sentence? — The Storm Surfer 00:55, 1 May 2007 (UTC)
Why not just write "it has become popular in recent years" (unless you actually mean the first years of the twentieth century)? Arnaudf 08:13, 1 May 2007 (UTC)
I think we should say whatever the source says. The word popular isn't very meaningful anyway. — The Storm Surfer 00:27, 2 May 2007 (UTC)

Replace image[edit]

If possible, the example tilt-shift photograph at the start of the article should be replaced with an example of an actual tilt-shift image, not a fake one. --Richmeistertalk 16:46, 31 July 2007 (UTC)

The actual tilt-shift would require an actual tilt-shift lens; whereas, tilt-shift effect could be given through various photo manipulation softwares.

merge from view camera[edit]

This article should either be renamed something like “artistic uses of a view camera” or similar and should incorporate and extend the information at View camera#View camera movements, or else this title should be redirected to that section. It's ridiculous to have sub-sections of the view camera article explain this topic better than this article (which ostensibly focuses on just that one aspect) does. --jacobolus (t) 10:49, 25 August 2007 (UTC)

I would argue no merge for the time being for several reasons: first of all, tilt-shift is not exclusive to view cameras, and lenses to accomplish this have been created both for still and movie cameras. Second, it's technically speaking not the view camera article's "job" or "scope" to discuss in detail the principles of tilt-shift - it should refer to it briefly and provide wikilinks to this article. Now it may be that the view camera article does the job better than this article does, but that should be dealt with by moving most of that specific content from view camera to here instead. Thanks, Girolamo Savonarola 20:41, 25 August 2007 (UTC)
I also argue against a merge at this time, and probably forever. If the section on Camera movements in the View camera article is trimmed and given a link to a main article, that article should be Camera movements or something equivalent, and this article eliminated (or redirected). “Tilt-shift photography” is an extreme neologism, and a phrase that I cannot imagine any view camera user ever uttering except in contempt. Those familiar with camera movements use “rise and fall” to describe vertical displacive movements, shift (or sometimes “cross”) for lateral displacive movements, “tilt” for rotations about vertical axes, and “tilt” for rotation about horizontal axes. I don’t think “tilt-shift” quite conveys what’s happening.
Some coordination among Perspective correction lens, Scheimpflug principle, and Camera movements is probably indicated. The Perspective correction lens article is nominally concentrated on preventing convergence of parallel lines in vertical objects, but most such lenses currently available (i.e., those for Canon and Nikon cameras) include both tilt and shift functions. I think that article should be moved to Tilt-shift lens with a redirect from the current title. Some description of the Scheimpflug principle would obviously need to be added, perhaps just enough to be in balance with the material on shift. Perhaps that article should cover only characteristics unique to small- and medium-format tilt/shift and PC lenses, and point to the one on Camera mevements for the bulk of the discussion. JeffConrad (talk) 08:15, 4 July 2008 (UTC)
After further thought, the best approach may be to keep this article and direct the reader to View camera#Movements (or wherever the main discussion ends up) for a more extensive discussion of camera movements. This article need some clarification, though. The currently vogue use of “tilt-shift photography” usually seems to mean selective focus achieved by rotating the plane of focus so that it passes through only a small part of the scene. If indeed that is the thrust of this article, it should be made more clear. Moreover, if that is the case, this article seems similar to Tilted plane focus, and some merger of that article and this one might be worth considering. Both articles also have technical errors that should be corrected. JeffConrad (talk) 21:21, 9 July 2008 (UTC)

Redirect from Tilt-shift lens[edit]

Should the redirect go here or to Perspective correction lens? This article refers to a technique rather than a lens. That article, of course, would need to have some material on tilt added; discussion of technique could be fairly minimal if the objective is to have View camera#Movements (or a new separate article) be the definitive treatment. JeffConrad (talk) 03:48, 8 July 2008 (UTC)

I've changed the redirect for Tilt-shift lens to go to Perspective correction lens since Shift lens, Tilt and shift lens, and Tilt-and-shift lens (new entry) all go there. Short term, this seems the best approach, even though that article currently has nothing on tilt (though it does briefly describe most currently available tilt-and-shift lenses). We still need to decide how to manage Tilt-and-shift lenses, Scheimpflug principle, and Camera movements to minimize duplication of material. If Tilt-shift photography remains, it should be as a separate article, because the term as popularly used means something quite different from camera movements as they are understood by most photographers who employ them. JeffConrad (talk) 05:41, 9 July 2008 (UTC)

Edit of 10 July 2008[edit]

I've revised the article in attempt to make it more readable and correct several technical errors. I've tried to keep it as non-technical as possible while still ensuring that it is correct.

A Google search for “tilt-shift photography” yields over 75,000 hits, but it's not always clear what is meant by the term. In most cases, it seems to refer to tilting the plane of focus away from the subject for a shallow DoF, but some sites also use it to refer to camera movements in the more traditional sense of preventing convergence of parallel lines and maximizing DoF. Accordingly, I've included the general description of tilt and shift in the lead section.

A few specific comments:

  • I used “refers to” rather than “is” because the latter would imply that use of movements on small-format cameras is tilt-shift photography, a statement with which many photographers, myself included, would disagree. I cannot imagine Adams or Weston ever using the term “tilt-shift photography”.
  • I changed a wikilink from Perspective (graphical) to Perspective (visual) because the former (in this context, essentially “point of view”) is determined by the position of the camera in relation to objects in a scene, and cannot be controlled by camera movements. The View camera article makes a big deal of this, but it's really just a matter of recognizing that photographers use “perspective” with two different meanings.
  • I eliminated terminology such as “sweet spots of focus” and “gradient of focus” because they are imprecise and unencyclopedic. Hopefully, I've adequately described whats happening with more correct term.
  • The section Use of effects obviously needs some work; I left it for now because I'm not quite sure what to do with it. I removed the last paragraph because there was an obvious confusion between control of perspective and of the plane of focus.

I've removed the stub designation. The article still obviously needs a bit of cleanup, but I'm not sure that great expansion is required—I think the best approach is to keep this article for the reader not interested in the technical details and direct others to the more detailed descriptions in other articles. Some diagrams might help, but most would duplicate those in the other articles. If others agree that the thrust of this article is selective focus, I suppose a diagram specifically showing how tilt can be used to achieve this might be helpful. JeffConrad (talk) 08:44, 10 July 2008 (UTC)

Example photos[edit]

Might be nice to include some (non-copyrighted) exampel photos on this page too. To show the effect of this type of photography and the pictures that you can get, anyone able to add some? —Preceding unsigned comment added by (talk) 10:56, 19 November 2008 (UTC)

I second that. Shinobu (talk) 14:20, 2 December 2008 (UTC)

Table of problems[edit]

I think the table at the top of the article ("This page is incorrect...") should be moved here, the talk/discussion page of the article. It is sort of odd having it on the main article and this practice is not done elsewhere on Wikipedia. --Thorwald (talk) 17:27, 27 February 2009 (UTC)

I agree completely; the edit is arrogant and particularly outrageous for an anonymous editor. Accordingly, I've moved it here. JeffConrad (talk) 19:27, 27 February 2009 (UTC)
This page is incorrect and needs to be revised by someone who understands camera movements
Tilt on a tilt-shift lens changes the plane of focus and is often achieved by first changing the angle of the lens relative to the image plan (film or sensor) then rotating the now angled lens through 360 degrees, for lenses which support this.
Perspective is controlled by changing the image plane, or generally speaking, changing the angle of the camera back in relation to the subject (more accurately, changing the angle between the recording surface, film or sensor, and the subject). Note, this also changes the plane of focus. Once an appropriate perspective has been selected, stopping down the lens (changing the depth of field) and/or use of tilt (changing the plane of focus) can be used to bring the whole subject back into focus. Thus perspective is now under control.

If the camera back is parallel on a vertical plane to a tall building, then all verticals in the building will not converge as they do when a camera is pointed up at a tall building.

As changing the angle of the lens or of the recording plane will change the plane of focus, this has many creative uses. Changing the angle of the recording plane has such a pronounced effect on perspective, that there are also many creative possibilities here too.
The image circle of a tilt-shift lens is generally much larger than the recording surface to allow for the movements. Once an appropriate position for the recording plane has been selected it is often necessary to use shift to position the image on the sensor.
It states below that shift controls perspective and this is simply wrong. Once perspective is under control, shift allows tuning of the image position.
Most lenses are circular and symmetrical. Rotating a lens would achieve nothing, apart from perhaps unscrewing it so it falls off.
I actually understand camera movements quite well. Technically, the editor is correct that perspective is controlled by the back rather than by shifting the lens; this is stated quite clearly in the section on shift but probably should be clarified in the lead section. The article Perspective control lens has the same problem; it probably also should be corrected, though doing so may meet some objection.
The statements about rotation are correct; there are three possible axes of rotation for a lens, and two are clearly stated in the section on tilt. But the editor seems to insist on interpreting “rotation” as being about the axis that isn't mentioned. Perhaps some clarification is needed, but a careful reading should indicate that there really isn't a problem.
This isn't to say that the article couldn't use considerable improvement.
I have a bit of a problem with the image claiming to show tilt but that actually shows swing. I realize that on small- and medium-format cameras the distinction is often ignored, but it seems to me that it would be much better to have a picture that actually shows tilt. At the very least, the caption should be changed to match the image.
I also have a problem with the apparently common association of “tilt-shift photography” with “miniature faking” because the character of the shallow DoF in closeup photography is quite different from that which obtains from rotating the plane of focus. But I'm not sure it's the role of WP editors to correct what we may see as common misconceptions.
A greater issue with the article may be that “tilt-shift photography” is a neologism that has two distinct meanings: one appears to relate to the conventional use of camera movements, the other appears to relate to a selective-focus effect that doesn't involve shift at all, and appears to be used by many folks who really don't understand the difference. It's tough to conclude much from Google searches, but they would seem to suggest that the latter use is by far the more common. In some extensive changes that I made in July 2008, I arguably gave more weight to the former meaning, and in so doing, may have somewhat hijacked the article.
So it may be appropriate to examine the general thrust of the article. Perhaps it should do more to stress the two different meanings. The challenge in so doing is that I'm not sure we have even a single truly reliable source for the either sense of the term. Because of this, I very deliberately used “refers to” rather than “is” in the opening sentence. To be honest, I cannot imagine Adams or Weston ever using the term in the former sense, and I have difficulty taking anyone seriously who makes statements like “photographers are tilt-shifting the focal planes of their cameras”. But personal opinions don't have a place in encyclopedia articles, and the term is used commonly enough that I don't think it's reasonable to simply dismiss it.
The challenge, then, is to arrive at an article that is informative and reflects current usage but also is accurate and has some supportable basis. I think it currently falls short of the mark. JeffConrad (talk) 19:27, 27 February 2009 (UTC)

Proliferation of link spam[edit]

I've once again removed the link spam that Dicklyon removed a couple of weeks ago. In the interest of even application of WP policy, I think many of the other links should get a hard look as well. This article is looking more like Flickr than part of an encyclopedia. JeffConrad (talk) 02:45, 13 July 2009 (UTC)

There are far too many external links here, many to personal web sites. Absent some ideas from others, I'm going make a first attempt at cleanup in accordance with WP:ELNO and WP:NOTLINK.

The following appear to be essentially personal web sites:

This is essentially a collective personal web site:

This equipment review would be more appropriate in Perspective correction lens, though that article already has a plethora of links:

This would seem more appropriate in Miniature faking, at such time as the site includes actual content:

This would would also seem more appropriate in Miniature faking, though its inclusion there has already met with some objection, and would need consensus to restore it there:

I also intend to remove references to “tilt-shift” and the like where used as a verb or noun, because there simply is no such technique (Disagree? Give a definition supported by a reliable source and I'll stand corrected). What's usually meant, even if not understood, is the use of tilt (when done optically) or progressive blurring (when done with digital postprocessing), which often works to about the same effect. I'm not quite sure what to use in its place. With optical methods, one gets selective focus using the Scheimpflug principle, and in some situations, miniature simulation (note that Vincent Laforet doesn't mention miniature faking). Once again, we go back to “What is ‘tilt-shift photography’ ” and what is the origin of the term. JeffConrad (talk) 23:01, 23 September 2009 (UTC)

No one has had any comments, so I've removed the aforementioned links. The case could probably be made that some of those that remain are marginal as well, but absent comment, I've left them. The first link aggregates links to a variety of sites that encompass several interpretations of “tilt-shift photography”, and obviates the need to include them here. JeffConrad (talk) 03:19, 14 October 2009 (UTC)

“Tilt-shift miniature faking”[edit]

The linked article appears to describe a postprocessing technique, which has nothing to do with this article. Moreover, the shallow DoF that obtains from using tilt with a small f-number isn't anything like that which obtains from close-up photography. The DoF is perpendicular to the plane of focus (with tilt, I use “perpendicular” loosely because the DoF is wedge shaped). Without tilt or swing, the PoF and the DoF are perpendicular to the line of sight; with tilt or swing, the PoF and DoF are at an angle, often a large one, to the line of sight. The effect isn't even close to similar. The linked article essentially says this, in the second paragraph under Techniques. But that article understates the case; digital postprocessing works better because selective focus using tilt doesn't simulate a miniature scene at all.

Unless someone can provided a reliable source for the current wording, I'm going to change the heading to Selective focus, and change the image caption accordingly. We could say that some claim to simulate a miniature scene using tilt, but indicate that the effect is quite different, along the lines of what I've stated above. Although this can easily be demonstrated from well-established principles, I don't have a good source that supports the final conclusion. But using tilt to simulate a miniature scene doesn't have a reliable source either, so if we insist on a specific citation, we may need to omit mention of miniature faking altogether.

As I've suggested in earlier comments, if Google hits are any guide, to many people, “tilt-shift photography” means selective focus, so expanding treatment of that application would seem appropriate. What's not appropriate is calling it “tilt-shift” or saying that it simulates close-up photography of a miniature scene. JeffConrad (talk) 21:41, 7 September 2009 (UTC)

I've cleaned this section up a bit, trying to make it correct while still covering all the bases. I removed the explicit WL to Tilt-shift miniature faking because that article actually seems to be more about miniature simulation using postprocessing that about simulation using tilt (that article, if it remains, needs some cleanup to make its topic more clear). JeffConrad (talk) 02:19, 10 September 2009 (UTC)

The photograph of the Oregon State Beavers stadium seems to be a digital fake. The EXIF info says it was taken with a Canon G9, a camera that does not allow for tilt or shift movements.Cbockermann (talk) 07:52, 19 September 2009 (UTC)

Indeed. So it probably doesn't really belong here. Perhaps it could go in Tilt-shift miniature faking as an example of simulating miniature using a (more or less) vertical gradient on a "horizontal" subject. I'm trying to clean up that article (see User:JeffConrad/Miniature Faking); it's proving to be a work in progress ... JeffConrad (talk) 09:34, 19 September 2009 (UTC)
The linked user page no longer exists; it was deleted after the material was incorporated into the article. JeffConrad (talk) 22:26, 23 September 2009 (UTC)
Of course, it may once again come back to “What is tilt-shift photography?” JeffConrad (talk) 10:04, 19 September 2009 (UTC)

The example image of "miniature faking" is inappropriate since it has not been produced using tilt-shift but by post processing. Can't someone find an example done with a tilt-shift lens or must there be a simulation of a tilt-shift lens simulating a miniature scene. Kwenchin (talk) 20:58, 23 February 2010 (UTC)

Again, it depends on what's meant by “tilt-shift miniature faking” and “tilt-shift photography”. Despite the bandying of vogue words, tilt/shift lenses are not big sellers, so I'd guess the vast majority of purported examples are done with postprocessing. To be fair, though, a sharpness gradient introduced in postprocessing often does a better job of simulating selective focus employing tilt than the latter does of simulating a miniature scene. JeffConrad (talk) 02:09, 24 February 2010 (UTC)

Edits of 26 September 2009[edit]

I've made a couple of changes to better reflect the multiple meanings of “tilt-shift photography”, and also indicate that it's a neologism unsupported by reliable sources. I think the article is reasonably balanced and essentially accurate, but we should recognize that it's still far outside the bounds of Wikipedia:Avoid neologisms:

“Wikipedia is a tertiary source that includes material on the basis of verifiability, not truth. To support the use of (or an article about) a particular term we must cite reliable secondary sources such as books and papers about the term—not books and papers that use the term.”

I'd rather have an unsourced article that's accurate than one that's unsourced and inaccurate. And the term is in such common use that it seems questionable to simply ignore it; moreover, several other related articles, such as Miniature faking, suffer the same deficiencies. But again, Wikipedia criteria are as they are, and not unreasonably so, and much of the material is open to challenge, possibly to the point that the article would need to be deleted. For now, I'm OK with fudging it if that's OK with others, because I have no good alternative to suggest. JeffConrad (talk) 03:43, 26 September 2009 (UTC)

December 9, 2007 New York Times article describing tilt-shift photography:- Kwenchin (talk) 04:09, 1 March 2010 (UTC)

I'm familiar with the article. It seems to imply, but does not state, that “tilt-shift photography” refers to selective focus achieved by employing tilt, which well may be what it means to most people. For news and analysis, I'd usually consider the New York Times a pretty solid source. But I'm not sure that holds for this magazine article. Though the author uses the term, he doesn't discuss it, so he's questionable as a source, as indicated by the WP policy I quoted above. Moreover, he speaks of “tilt-shift pictures”, suggesting that he doesn't really understand the difference between tilt and shift. I'm also led to wonder by the use of phrases such as “skewing the gradient of focus” and “somebody spent an hour or two getting the level of Gaussian blur perfect enough” (assuming “Mini Portsmouth” refers to the image in the article, it seems a pretty simple application of Lens Blur to me). I'm not sure it's important that the author of an article such as that in the NYT Magazine understand the technical issues; however, a modicum of understanding would seem a prerequisite for an author to be cited as a reliable source for this article.
From a technical standpoint, interviews with Vincent LaForet and Norman McGrath at the Canon Digital Learning Center are on far more solid ground, though they still don't really discuss the term. And the site is a pretty heavy Canon promo, so it may not be the best candidate even for an external link. One could interpret the different usage in the two interviews as indicating either that
  1. “Tilt-shift photography” refers to using tilt for selective focus, as LaForet implies; or
  2. The term means different things to different people (directly from LaForet's comments, and by inference from McGrath's).
Although I think both interviews are well worth reading, I don't think either really would help much with the issue at hand here (I suppose we could add something like, “Vincent LaForet has used ‘tilt-shift photography’ to describe ...”, but I don't think we could reasonably go much further). JeffConrad (talk) 12:46, 1 March 2010 (UTC)

Factors affecting amount of blur with tilt[edit]

The amount of blur depends on the f-number as well as the tilt. But the relationship isn't quite that simple.

I don't have a closed-form expression for DoF, but if θ is the lens tilt, Ψn is the near angular limit of DoF, Ψf is the far angular limit of DoF, c is the acceptable circle of confusion, and f is the lens focal length, the f-number N required for a given angular DoF ΨfΨn is

N=\frac{f}{c}\frac{\tan \theta \left( \tan {{\psi }_{\text{f}}}-\tan {{\psi }_{\text{n}}} \right)}{\tan {{\psi }_{\text{f}}}\left( \tan {{\psi }_{\text{n}}}-\tan \theta  \right)+\tan {{\psi }_{\text{n}}}\left( \tan {{\psi }_{\text{f}}}-\tan \theta  \right)} \,.

If θ is small in comparison with with the angle Ψ of the PoF with the image plane, as often is the case when tilt is used to provide selective focus, this simplifies to

N\approx \frac{f}{c}\frac{\tan \theta \left( \tan {{\psi }_{\text{f}}}-\tan {{\psi }_{\text{n}}} \right)}{2\tan {{\psi }_{\text{f}}}\tan {{\psi }_{\text{n}}}} \,.

If the tilt is small, as is the case with current tilt/shift lenses, we can take tan θθ, so that

N\approx \frac{f}{c} \theta \frac{\left( \tan {{\psi }_{\text{f}}}-\tan {{\psi }_{\text{n}}} \right)}{2\tan {{\psi }_{\text{f}}}\tan {{\psi }_{\text{n}}}} \,.

Working backwards, the amount of blur increases with decreasing f-number increases with tilt, and in general, decreases with the angle of the PoF. For a given tilt, the angle of the PoF increases with lens-to-image-plane distance (controlled by the focusing ring or knob). Because the DoF is wedge-shaped, the blur increases with distance (angular or perpendicular) from the PoF. And of course, for given settings and angular distance from the PoF, the amount of blur decreases with distance from the camera.

In general, the angular DoF increases with the angle of the PoF with the image plane (much as DoF increases with distance from the camera when the lens is not tilted). Consequently, blur decreases with the angle of the PoF with the image plane; accordingly, I've revised the statement above.
The situation further simplifies if the angle of the PoF with the image plane approaches 90°. We then can use the angle ξ of the PoF with the perpendicular to the image plane, and make use of the small-angle approximation for the tangent. We have ψ = 90° − ξ; using the relationship
\tan \psi = \tan \left ( 90^\circ - \xi \right) = \cot \xi = \frac 1 {\tan \xi}\,,
we have, when ξf and ξn are small,
\tan \psi_\mathrm{f} \approx \frac 1 {\xi_\mathrm{f}}
\tan \psi_\mathrm{n} \approx \frac 1 {\xi_\mathrm{n}} \,.
The subscripts n and f still refer to the angular distances from the PoF; ξn is actually at a greater angular distance from the perpendicular than is ξf. The required f-number is
N \approx \frac {f}{c} \theta
\frac { \frac 1 {\xi_\mathrm{f}} - \frac 1 {\xi_\mathrm{n}}}
{ 2 \frac 1 {\xi_\mathrm{f}}  \frac 1 {\xi_\mathrm{n}}} \,;
cross multiplying in the numerator and simplifying gives
N \approx \frac {f \theta}{2c} \left (\xi_\mathrm{n} - \xi_\mathrm{f} \right ) \,.
Rearranging gives the angular DoF
\xi_\mathrm{n} - \xi_\mathrm{f} \approx \frac {2Nc} {f \theta} \,.
Substituting 90° − ψ for ξ and rearranging gives, equivalently,
\psi_\mathrm{f} - \psi_\mathrm{n} \approx \frac {2Nc} {f \theta} \,.
For ξ = 20°, the error from the small-angle approximation for the tangent is under 5%, which is for practical purposes negligible in the context of DoF. Consequently, the final expression above might reasonably used whenever the angle of the PoF with the image plane is greater than about 70°, which probably often is the case when using tilt for selective focus. So under that condition, for a given angle of the PoF, the angular DoF is directly proportional to the f-number and inversely proportional to the tilt, much as Kwenchin indicated. This is obvious to anyone who has ever used tilt for selective focus, especially with a long lens. Perhaps this behavior is sufficiently accepted that we reasonably state it. But we can't use the Stroebel reference to support it. JeffConrad (talk) 01:19, 4 April 2010 (UTC)

Although it would be nice to include at least a brief summary of the above, I'm not sure we can reasonably do so without support from a reliable source. Unfortunately, I'm not aware of a citable source for any of this, so to use it, we'd need to include the derivation (probably in the article Scheimpflug principle). The derivation is straightforward but a bit tedious for a Wikipedia article, and I think the Scheimpflug article is already a bit heavy on math. If someone has a good source, however, we could directly cite it. JeffConrad (talk) 09:14, 3 April 2010 (UTC)

Then the sentence can be modified thus: "The amount of blur for the unsharp regions can be controlled by the angle of tilt and f-number." and put after the reference. ps The LensBaby website says that their lens is not a tilt-shift lens. A better example would be from a tilt-shift lens. Kwenchin (talk) 23:49, 3 April 2010 (UTC)

Woops ... I somehow missed this comment. More or less, I agree on both points.
Putting the statement after the reference addresses misattribution to Stroebel, but not the lack of support for the statement. We should bear in mind that WP policy is concerned not so much with the accuracy of statements as with their verifiability, so anything we say should be scrupulously accurate so as not to invite challenge (if we can't support it, any editor can remove it). Toward that end, I might prefer a slightly more rigorous introductory statement, perhaps describing what affects angular DoF, just because “blur” is a bit vague and also a bit more complicated (for a given scene element, the blur also depends on the distance from the PoF). But the greater issue is whether we can reasonably make this statement absent support from a reliable source; I suppose if no one objects, we can give it a shot.
If we decide that we can make such a statement, I think it belongs in the second paragraph. The second sentence in that paragraph (which I added) is only marginally supportable, and could be removed to make way for something more concrete and arguably more useful.
Whatever might be said should be consistent with the following principles:
  • When the lens is tilted, the PoF is at an angle to the image plane.
  • When focus is adjusted, the PoF rotates about an axis below the lens (strictly, the axis is at the intersection of the front focal plane and a plane through the center of the lens).
  • The focus control adjusts the orientation of the PoF; the tilt adjusts the distance of the axis of rotation from the center of the lens.
  • The DoF is wedge shaped, with the apex of the wedge at the PoF rotation axis; the angle at the apex of the wedge (the angular DoF) is controlled by the lens f-number, but it also depends on the tilt and the angle of the PoF with the image plane.
I think the first three items are adequately supported by the article on the Scheimpflug principle. I'm not sure the last item is disputed, but again, I'm not aware of a citable source to support (by implication, Merklinger provides some support, but extending that support to the entire item is a bit of a stretch).
A LensBaby allows tilt but not shift; its main difference from a normal tilt/shift lens is the significant curvature of field, so it's tough to meticulously render two or more elements sharply. Because the blur in the example image looks to me to result more from the field curvature than the tilt, I'd honestly have no problem with removing the image from this article; of course, we have the same issue with the image of the football stadium that was apparently done in postprocessing. Yet again, it ultimately comes down to what “tilt-shift photography” is. I think we might ultimately be better off with a separate article on camera movements, covering both view cameras and tilt/shift lenses, and with regard to tilt, covering selective focus as well as getting everything sharp. The article could then be linked to several other articles that currently discuss movement. Such an article could make brief mention of “tilt-shift photography”. JeffConrad (talk) 08:07, 4 April 2010 (UTC)

The sentence is just putting into words what's in the equations. The LensBaby is always out of focus round the edges. The tilting is used to move the sweet-spot around. Although it is used for selective focus it has nothing to do with tilt-shift photography. Kwenchin (talk) 11:10, 4 April 2010 (UTC)

Once again, it depends on what's meant by “tilt-shift photography”—and I don't think that's settled. Moreover, “sweet spot” is meaningless LensBaby advertising hype. I have no problem with removing the LensBaby image and in fact, any mention of LensBaby in the article, though I suspect others may disagree.
I've again removed the unsourced statement about how blur can be controlled—let's give others some chance to comment. Perhaps there's partial support in what I've discussed above, but it still depends on the first equations I introduced, without derivation or support from a reliable source. If no one objects, we can add the statement. But if we do, we should do so systematically. The factors that affect angular DoF apply to tilts and swings generally, so they should first be mentioned in the general section Tilt. And they should relate to specific quantifiable entities such as angular DoF; at least such statements could be supported by derivations. We perhaps can additionally state how this relates to blur. If no one objects, I'll give this a shot. But again, let's at least give folks a few days to comment.
A minor point: use of tilt in media is a topic separate from the concept of selective focus and how it's achieved, so it belongs in a separate paragraph.
As I hope I've made clear, you and I don't really disagree on factors that affect the angular DoF. The issue, as I've repeatedly said, is adding unsupported statements, which technically is out of bounds with regard to WP policy. The situation here is perhaps somewhat special, in that several things obvious to anyone who has played with selective focus using tilt and swing lacks lack citable sources. So perhaps we can push it, but let's give others a chance to comment. JeffConrad (talk) 12:32, 4 April 2010 (UTC)

Tilt is not a primary sharpness control[edit]

I neglected to mention something that seemed obvious to me, but perhaps is not so to others. Although the tilt affects the angular DoF, it's usually not available as a primary control. Perhaps it's worth a quick look the simpler situation that obtains without tilt. The focus control (usually a knob or ring) determines the position of the plane of focus, and the lens f-number determines the extent of the DoF, and hence the blur of the unsharp areas. When the lens is tilted, the position of the PoF is determined by the focus and the tilt.

As Jamesmcardle and Vincent Laforet indicate, the first step in effective use of tilt for selective focus is carefully choosing the position of the PoF to determine what is sharp and what is not. Once the position of the PoF is fixed, so are the tilt (and perhaps swing) and the focus. If the tilt is then adjusted to change the angular DoF, the position of the PoF is also changed. Thus the primary control of angular DoF (and the blur for unsharp elements) is the lens f-number. In most cases, adjusting tilt to control the blur would be akin to changing focus to control the blur without tilt, without regard to what's left in focus.

There are cases in which the tilt can be used as a blur control. For example, if photographing a row of buildings that cross the field of view at a large-to-moderate distance and it is desired to give selective focus to one or more of them, and there is nothing significant in the foreground or background, the tilt and focus can be adjusted to control the width and position of the focus “window”. Laforet describes using a similar approach in aerial photography, where there seldom are objects in the foreground and there seldom is a background.

Though many books have been written describing camera movements, usually on view cameras, surprisingly little has been said about exactly what happens with each control. It appears that even Stroebel didn't fully understand the details, and Sinar admit they didn't either until the development of the Sinar e in the late 1980s. Merklinger made the first widely read analysis in his articles in Shutterbug in the early 1990s, but may have made things seem overly complicated for many readers. As I indicated above, the principles are quite simple:

  • The orientation of the PoF is determined by the focusing control
  • The axis about which the PoF rotates as focus is changed is determined by the tilt.
  • In combination, the tilt and focus determine the position of the PoF.
  • The angular DoF (and, in effect, the blur of the unsharp areas) is determined by the lens f-number.

Though most of this is fairly easy to prove, and can be synthesized by grabbing pieces from several sources, I'm not aware of a current citable source that directly states everything. Perhaps that will change with the seemingly increased interest in tilt/shift lenses, but at present, I think we need to be very careful about what we say, especially without support from a reliable source. JeffConrad (talk) 02:08, 5 April 2010 (UTC)

I've made a couple of changes to clarify the limitations on using tilt as a sharpness control while simultaneously choosing the position of the PoF; see if they help. The concept isn't difficult, but at least for me, it's proving harder to simply explain than I expected. If the effects of the various controls aren't clear, perhaps the article should include a bullet list such as that above. JeffConrad (talk) 09:19, 15 April 2010 (UTC)

Edits of 6 April 2010[edit]

Both Kwenchin and I seem to have overlooked the unreferenced material on the relationship between tilt and angular DoF already in the article ... and which I seem to have added in September 2009, so I probably have no business objecting to it now. Moreover, if others had strong objections, they presumably would have raised them. And if people now object, I suppose they will so indicate.

I've expanded the discussion of factors that affect angular DoF, beginning in the section Tilt, because they apply when the objective is to get everything sharp as well as when the objective is selective focus. I've mentioned using a large tilt to decrease the DoF, while including the caveat that this also affect the position of the DoF. I think everything I've added is correct and defensible, and finds some support in the Depth of field section of the Scheimpflug principle article. A glance at my notes suggests that a solid derivation of the first equation I presented above would be at least as long as the explanation provided, so it probably should be considered only as a last resort.

I've removed the image of selective focus achieved with the LensBaby lens, because I agree with others here that it has little to do with the subject at hand. I've also tagged the WL to freelensing, because the article to which the WL points relies on a source that freely admits that they grab stuff from the web, which hardly qualifies them as reliable. A quick Google search suggests to me that “freelensing” is yet another semi-viral net neologism; I'll change my mind if a reliable source can be provided, but absent a reliable source, the link will soon be history. I suppose we could use weasel words to the effect of “some people use ‘freelensing’ to describe ...”, but I agree with WP policy that this usually doesn't improve articles.

Hopefully, the changes address some of the issues discussed above. JeffConrad (talk) 08:56, 6 April 2010 (UTC)

Sometimes tilt can be quite large angles (30 degrees) eg This is only a tilt lens but they suggest combining it with their shift adapter to make a tilt-shift system. Kwenchin (talk) 19:42, 8 April 2010 (UTC)

I'm not quite sure how this relates to the recent edits; are you suggesting that the article as it now reads may not be correct for large tilts? JeffConrad (talk) 03:49, 9 April 2010 (UTC)

Field Curvature[edit]

"Without tilt, the image plane (containing the film or image sensor), lens plane, and object plane are parallel, and objects in sharp focus are all at the same distance from the camera"
this is not accurate as different points on the plane of focus are different distances from the camera, see petzval field curvature. if someone could rewrite this bit to reflect that that'd be rare. —Preceding unsigned comment added by (talkcontribs)

We're generally not dealing with single-element lenses, and most multi-element lenses have reasonable correction for flatness of field. Although the field usually isn't perfectly flat, it's usually sufficiently so for the purposes of an article such as this or for treatments of depth of field. We should bear in mind that Petzval curvature is not the only departure from the simplistic Gaussian surface normally assumed in discussions relating to practical photography. It is customary to ignore aberrations because
  1. They're different for every lens design.
  2. Considering them would sufficiently complicate topics such as depth of field or the Scheimpflug principle as to make them unmanageable.
If we were to be strictly correct, there's an additional complication when the lens and image planes are not parallel: the blur spot is elliptical rather than circular (at least for a perfectly round aperture stop). Assuming we had data relating to perceived lack of sharpness for various elliptical spots (i.e., what governs: The long axis? The area?), we'd have compound curved surfaces for the near and far limits of DoF. Although that's strictly the case, the departure from planarity is minimal on 4×5 except for extreme movements, and essentially negligible for any combination of movements with any current small-format tilt/shift lens. Accordingly, for most situations of practical interest, we can treat the near and far DoF limits of a tilted lens as planar.
So, yes, I agree that what's said here is a simplification of the real situation. But it's only one of many that we normally ignore in order to keep the problem manageable. A lens designer obviously cannot ignore aberrations, but this article relates to practical photography rather than lens design. Moreover, I don't think we could reasonably discuss Petzval curvature without also discussing other aberrations (and perhaps the ellipticity of the blur spot). Were we to include such material, we'd probably lose most readers in the middle of the lead section. JeffConrad (talk) 01:21, 3 September 2010 (UTC)
I agree that we should ignore aberrations for this article, but what I was getting at is that what the article is saying is only strictly true if we assume the lens has curvature of field. I made a picture to demonstrate: —Preceding unsigned comment added by (talk) 00:34, 6 September 2010 (UTC)
and that should be 14 by the way, I can't do square roots in my head. —Preceding unsigned comment added by (talk) 00:36, 6 September 2010 (UTC)
I agree that the distance from the exit pupil to the edge of field is greater than the distance on the optical axis, but I'm not quite sure I understand your point; what specifically do you think is incorrect? What we say here is consistent with every treatment of this subject I've ever seen, including Stroebel, Merklinger, Wheeler, and Evens (relatively few people have really covered it). JeffConrad (talk) 02:03, 6 September 2010 (UTC)
"objects in sharp focus are all at the same distance from the camera"
Generally, this is true; do you have a source that suggests otherwise? JeffConrad (talk) 18:32, 6 September 2010 (UTC)
you said yourself, "the distance from the exit pupil to the edge of field is greater than the distance on the optical axis." for simplicity's sake let's pretend a camera with an ideal lens is at (0,0,0) facing (1,0,0) and focussed at 1. the plane of focus can then be defined by (1,0,1), (1,0,0) and (1,1,0). if we place objects at (1,0,0) and (1,0,1) both will be on the plane of focus and be in focus, however, the former is 1 unit from the camera and the latter is sqrt(1^2+1^2)=sqrt(2) units from the camera according to the Pythagorean theorem which != 1, and which contradicts the article's assertion that both are "the same distance from the camera." I realize that the article's meaning is apparent, but it's not strictly true and could be confusing for people unfamiliar with this sort of thing.
That's not how it works—object and image conjugates are measured perpendicular to the lens plane, not on the slant distance from the intersection of the optical axis and the lens plane. JeffConrad (talk) 02:41, 7 September 2010 (UTC)
Upon further thought, perhaps I understand what you're saying: that someone might literally interpret “distance from the camera” to mean something other than “distance from the image plane”. Though it may be possible, I think it's unlikely. We could say “distance from the image plane”, but I think most readers would find the added formality more offputting than “distance from the camera”. JeffConrad (talk) 03:03, 7 September 2010 (UTC)
Though I don't think it's relevant to this article, I'll concede that there is one situation where many photographers do get confused about “distance from the camera”. I'm not sure this really indicates a misunderstanding of distance as much as simply not stopping to think that the distance changes, but in any event, “focus/recompose” with small-format cameras is a common technique (perhaps a remnant of the days of manual focus), and it can result in misfocus at large apertures. JeffConrad (talk) 08:38, 7 September 2010 (UTC)
I expect the average reader would take "same distance from the camera" to mean that you attach a tape measure to the camera and measure to your subjects. I know I for one believed for a long while that lenses were designed to have perfectly spherical focus, probably due to confusing wording like this. Perhaps the wording is correct in this particular area, but I still think "distance from the image plane" as you suggested would be a better choice.
Perhaps it's just me, but I find it hard to imagine a design for spherical focus given a flat (more or less, in the days of film) image plane. I guess in most cases, the subject distance would be more or less perpendicular to the subject, but it's possible that the average photographer may not give this much thought—as the comment on “focus/recompose” (standard practice before multi-point AF) seems to illustrate. Let me review a few sources and see if someone has a simple way of saying this. One issue is that I think this article should be reasonably consistent with what we say in others, even if we need to make similar changes elsewhere. JeffConrad (talk) 23:04, 7 September 2010 (UTC)

────────────────────────────────────────────────────────────────────────────────────────────────────I've added an introductory sentence to the subsection Tilt indicating the the plane of focus is perpendicular to the lens axis—see if this helps. We could state something to the effect of “objects in sharp focus are all at the same distance from the image plane”, but I hesitate to do so because, except for hand-camera lens distance scales, we usually speak of the object distance rather than the image-plane-to-subject distance. A review of nine sources indicated that they all seem to assume that “distance” is understood to be measured perpendicular to the image plane. The wording I added was suggested by Langford (1973) and Stroebel (1976); the other sources, including Tillmanns (1997) and Ray (2002), had little (at least that I could find) to say about this. JeffConrad (talk) 09:39, 8 September 2010 (UTC)

It looks good to me, much clearer I think.

Source for history of view camera movements[edit]

In retrospect, it would appear that Porlob intended {{cn}} rather than [[cn]]. But I’m still a bit confused by the reference to the 1960s—that time was the introduction of the PC-Nikkor lens for 35 mm cameras, and had nothing whatsoever to do with view cameras. Is the question whether view cameras had movements long before the 1960s? The Scheimpflug principle was clearly known to Jules Carpentier in 1901, though I concede this isn’t direct evidence of the incorporation of tilt movements on view cameras. And it’s probably debatable whether even 1901 would qualify as “the early days of photography”. JeffConrad (talk) 10:26, 2 February 2011 (UTC)

I’ve made a guess at the cause of Porlob’s objection, and have revised the first sentence of History and use in attempt to address it. See if this works. JeffConrad (talk) 09:24, 3 February 2011 (UTC)

The case for a Disambiguation Page[edit]

I think there should be some kind of Wikipedia entry for the term tilt-shift photography, as it's popping up more frequently, and, like me, readers may try to come to Wikipedia to see what the heck these hipsters are talking about.

It looks to me like this unfortunate neologism came about because there isn't a snappy, technically accurate generic name for this style. Now, if it were a trademark it'd be up to the owners to also conceive of a generic equivalent up front, and we could use that, but no such law exists for neologisms, and we're stuck with a pseudo-technical buzzword, but no accurate technical or art-historical term. I guess Miniature Faking is OK for now, but we eventually need to come up with something better (good luck with that :-) ).

Pages already exist to hash out all the various camera movement and plane-of-focus stuff being discussed here; there is only one new subject that's not covered in the older wiki entries, and that is this... um... emerging fad/fashion/trend/genre of imagemaking that has been unfortunately tagged "tilt-shift". This is new; we need a page on that--but it should be primarily about the artistic/creative/esthetic side. As it stands now, we're getting bogged down in the competing technical and artistic aspects of this subject (isn't that photograpy in a nutshell?). Therefore...I propose that "tilt shift photography" point to a disambiguation page something like this:

"Tilt-Shift Photography may refer to..."

· A distinctive genre of visual imagery such as Miniture Faking and the various means of producing it

· Two of the available Camera Movements

· A Tilt Shift Lens aka perspective control or PC lens for small/medium format cameras

This disambig would accomodate three types of readers who might land there: the reader looking for the image style that's all the rage now, someone who sees a Tilt-shift lens for sale on e-bay and needs to know what it is, or the more serious reader who is looking to explore what the "real" tilt and shift mean.

The Miniture Faking page (or whatever we decide to call it) would be a migration of most of the content here (the current "tilt-shift photography) but would be shortend and overhauled to emphasize the esthetic style with brief summaries of the techniques used, both traditional and digital, linked to more in-depth articles. Most of these techniques are already covered. (talk) 20:34, 27 March 2011 (UTC)

A case can probably be made for disambiguation; as I’ve suggested here many times, the preponderance of usage seems to be in the first sense noted above. But there remain several problems with this topic:
  1. The greatest is the lack of reliable sources—I’m not sure we have a single authoritative source for the definition or the origin of the term (personal blogs and the like that have been used here from time to time are not WP:RS). I strongly suspect that the origin of the term is precisely as we currently state in the first paragraph of this article, but we really don’t have a reliable source to cite.
  2. The vast majority of the time, usage in the first sense is a misnomer, uttered by those who know not of what they speak.
  • There simply is no such thing as “tilt-shift”; as noted here and elsewhere, there are tilt and shift movements, and the latter is seldom used in the photography referred to by the first sense of the term. A source that uses the term as if it were an actual technique is most probably not reliable.
  • Though we lack a reliable source for the numbers, a glance at the Web suggests that the vast majority of “tilt-shift photography” is done in software. Perhaps what’s meant is that the intent is to simulate the effect of using tilt to produce a shallow angular DoF, though quite honestly I’d be surprised if more than a few who use the term are aware of this.
  • Most “miniature faking” using “tilt-shift photography” is anything but. The effect of using tilt with a small f-number is, in general, quite different from that which obtains when photographing a miniature scene at significant magnification, as a direct comparison of the two would quickly show (though I concede that it’s tough to find handy, accurate miniatures of typical outdoor scenes). The paper by Held et al. also clearly shows this.
To an extent, we probably need to bow to widespread usage, but we also need to be careful to not convey misinformation. What “tilt-shift photography” evidently refers to much of the time is the use of software to simulate the effect of tilt used to produce small angular DoF for selective focus, and any article on the topic would need to make this clear.
We already have articles Miniature faking and Tilted plane focus; perhaps one or both already serve some of the suggested purposes. The former is devoted to techniques (including some that actually work) that simulate miniatures; the latter is devoted more to aesthetic considerations, but does not mention “miniature faking”. We have several paragraphs that discuss selective focus in the Depth of field article. An article devoted to camera movements, covering both those on view cameras and rigid cameras (or whatever non–view cameras are properly called) has been suggested several times but doesn’t seem to have found much support; to me, it seems that this article is reasonably close to covering such a topic. It might remain to be seen whether the main editors of View camera would be amenable to moving the bulk of the material devoted to movements from that article to a separate article that only covers movements. Perhaps the problem with previous merger proposals was simply that the wrong mergers were suggested.
Again, the most common usage of “tilt-shift photography” probably is the part we cover here in the subsection Miniature faking, so perhaps it’s not the best title for this article. But anything we develop devoted exclusively to “tilt-shift photography” or “tilt-shift miniature faking” needs to be accurate and supported by reliable sources. Yes, in many cases the scare quotes are indicated because as noted, both terms are usually misnomers. And a different article with the same title as this one would need to make that clear from the beginning. JeffConrad (talk) 02:50, 28 March 2011 (UTC)

Merge suggestion[edit]

I agree that there is too much overlap in the articles:-
Scheimpflug principle
View camera#Movements
Perspective control
Perspective control lens
Tilt–shift photography
Miniature faking
This all needs to be tidied up. Maybe the individual articles can still exist but some could be greatly shortened by taking out repetition of material in the other articles and having links to them. When a section directs the reader to a main article there is little point in repeating a lot of the main article's information and making readers read much of the same information again. QuentinUK (talk) 15:32, 24 February 2013 (UTC)

AGREED the content of the Tilt-shift and Perspective control articles overlap to such a degree that they are almost "identical". They use the same explanations, cover the same subject matter, use the same illustrations. Apart from trivial distinctions, one is longer than the other, they have different titles, etc., I can see no substantive difference so find it hard to see any reason not to merge the two. LookingGlass (talk) 16:19, 13 January 2014 (UTC)

Depth of field[edit]

It's not really clear here, but does a tilt-shift lens change the actual depth of field, or does it simulate it by creating areas of different sharpness on the focal plane? Kortoso (talk) 23:15, 24 October 2013 (UTC)