Talk:Canon EF 100–400mm lens
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I changed the "Unique features". "Cute" is not a useful description. I am also going to take out the statement regarding "Many users..." and dust. "Many" is a weasel word. By saying "Many people blah blah blah...", you can support any statement you wish. The media uses it all the time to inject bias into their stories. If someone has some numbers regarding the percentage that are sent to service centers for cleaning, and how that compares to the average L-series zoom lens, we can put that in. But statements that start with "Many people(users)..." do not belong in an encyclopedia. Many people think 9/11 was an inside job. Many people believe Bush works for the Illuminati. Many people believe aliens have performed surgery on them. Etc. All those statements are true, but also provide no useful information. Even if one is seeking information on opinions, the only proper way to do that is to report the results of a properly conducted survey. ANY opinion can be supported by "Many people..."
I also took out the statement regarding the popularity of the lens. We don't have numbers here to either back up that it is popular or why. Again, some actual numbers comparing it to other L-series telephoto zoom lenses would be useful. Just saying "it is popular" is not.
Hi guys! I really need help! I have these Canon 100-400mm lens and I use them on my 5D. I can tell you it's a great lens, but my question is different The maximum focal length of these lens is 400mm, right? But when I take a ruler and physically measure the maximum length of the lens, it comes down to slightly less than 30cm, or 300mm. How can I prove to myself (i.e. physically measure) that the focal length of the lens is 400mm??? I hope you understood my question. I'm just being curious. Thanks. M.efimov (talk) 18:00, 30 July 2008 (UTC)
- The focal length is not necessarily exactly the physical length of the lens. Think of 16mm lenses, for instance, or even more of the Diffractive Optics (the 70–300 mm DO is ridiculously shorter than 300mm). In short, one can use optical tricks to obtain a given focal length in a compact lens.
- To measure the optical focal length, you should measure the angle covered by your lens -- or the distance covered by the width of the image at a given distance. Rama (talk) 18:21, 30 July 2008 (UTC)
- At the 400mm focal length end of the zoom range, this lens is a true telephoto lens which means that the optical centre (400mm from the focal plane when set to infinity) is outside of the physical structure of the lens and in fact in front of the large object glass. 22.214.171.124 (talk) 10:57, 27 July 2009 (UTC)
I have deleted the panel stating that the article would be deleted as I found it to be useful and think it should remain. Whilst it may not be linked to directly I think many will reach it via the various Wikipedia articles on Canon's EOS cameras and their matching EF lens ranges.
The lens has gained something of a reputation for being a 'dust-pump', possibly due to its design, however most buyer comments state that this is not a problem; to address this I have added a) a link to Wikipedia's own article on dust reduction systems and b) to the customer review ratings on Amazon (170 reviews, average 4.7/5.0) and B&H (573 reviews, average 4.5/5.0).
I have also made some minor corrections to punctuation.
I note that a paragraph on a supposed dust ingress problem has been repeatedly deleted and reverted. Although this would qualify for original rearch, I do own one of these superb lenses. I have not had a dust problem that I can attribute to the lens, but the construction does pump large amounts of air in and out of the lens body during zooming (you can actually feel the draght). There does not appear to be any attempt to prevent dust entering during such zooming. This is consistent with the age of the design as it pre-dates the digital era. More modern lenses designed in the digital era certainly seem to have some attempt at preventing dust ingress.
If the paragraph is to be deleted, then some evidence should be provided that this is not a genuine problem. Although few of the mainstream review sites mention it (and those that do, make it clear that they haven't specifically tested it), there are a number of gripes from users on several discussion forums, however a discussion forum is not a reliable reference beyond providing anecdotal evidence. 126.96.36.199 (talk) 18:15, 4 March 2012 (UTC)
- I note that yet another edit has taken place claiming that the info is 'false'. The repeated use of the same phraseology betrays that this is clearly the same user ( WP:SOCKPUPPETRY). No evidence was provided despite previous demands. Further an incorrect claim was made that the body of the lens is 'sealed' from the camera body. Even a cursory examination of the lens will reveal a variable air space that has no separation from the camera body. 188.8.131.52 (talk) 08:43, 12 March 2012 (UTC)
- It is true that there appears to be little positive evidence that the lens features any form of dust sealing (apart from user comments on many forums). Note should be made, however, that Canon explicitly mention the sealing of the vast majority of their flagship 'L' series lenses as part of the feature of the lens. Check the owner's manual for the EF 75-300mm f/4.5-5.6L USM lens here, for example (Page 2). Page 4 of the manual specifically refers to the dust sealing ring on the lens mount and the effect that it may have on the camera's mount. By contrast the 100-400 mmL lens is notable in that there is no mention of sealing in the features of the lens as can be seen from it's owner's manual found here (again page 2) and no mention of any posible deliterious effect on the camera mount. An examination of an example of the lens reveals that there is no rubber dust sealing ring. It is indeed quite true that the majority of the 'L' lens line up were designed in the age of digital photography. The design of the 100-400 mmL lens is by far the oldest and does pre-date the digital era when lens dust sealing was considered unnecessary for photographic film. The lens does have a large space in it which does change size with zooming and the ingestion and exhaustion of air can be clearly be heard and felt, mostly from the gap under the zoom touch adjustment ring. An examination of my own lens, which has had a fair bit of use, shows quite a few dust particles clinging to the flock lining. That said, I have not personally had a problem with dust on the sensor that I can specifically pin on the lens. It also has to be said that Canon would appear to have not felt the need to update the design and produce a sealed 'II' model. DieSwartzPunkt (talk) 18:00, 19 March 2012 (UTC)
I updated the part talking about this lens on a crop frame sensor to be more accurate. On a crop frame the FOV is equivalent to a longer lens but it does not improve the optical quality. So I also removed the following sentence that referred to this as an advantage since that isn't necessarily true. Rberning (talk) 16:09, 26 August 2013 (UTC)