Maksutov telescope: Difference between revisions
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[[Image:Maksutov 150mm.jpg|right|thumb|250px|A 150mm [[aperture]] Maksutov-Cassegrain telescope.]] |
[[Image:Maksutov 150mm.jpg|right|thumb|250px|A 150mm [[aperture]] Maksutov-Cassegrain telescope.]] |
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The '''Maksutov''' |
The '''Maksutov''' is a [[catadioptric]] [[telescope]] design invented in the 1940s that employs a full diameter [[Lens (optics)#Construction of simple lenses|positive meniscus lens]] (commonly called a "corrector plate") to correct the problems of [[Off-axis optical system|off-axis]] [[Aberration in optical systems|aberration]]s such as [[Coma (optics)|coma]] found in [[reflecting telescope]]s while also correcting [[chromatic aberration]]. The design is most commonly seen in a [[Cassegrain reflector|Cassegrain]] variation, with an integrated secondary, that can use all-spherical elements, thereby simplifying fabrication. The chief disadvantage of the design is that it does not scale up well to large apertures (>250 mm/10 inches), since the corrector plate rapidly becomes prohibitively large, heavy and expensive as the aperture increases – most commercial manufacturers usually stop at 180 mm (7 inches). |
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==Invention== |
==Invention== |
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This telescope design uses a spherical [[primary mirror]] in conjunction with a positive meniscus spherical surfaced "meniscus corrector shell" at the entrance pupil in a design that takes advantage of all the surfaces being nearly "spherically symmetrical"<ref>[http://www.quadibloc.com/science/opt0203.htm John J. G. Savard, "'''Miscellaneous Musings'''"]</ref> to correct [[spherical aberration]], a significant problem in other types of [[reflecting telescope]]s<ref>[http://www.riverofstars.net/JSCAS/Starscan/Feb04.pdf Dmitri Maksutov: The Man and His Telescope]</ref>. |
This telescope design uses a spherical [[primary mirror]] in conjunction with a positive meniscus spherical surfaced "meniscus corrector shell" at the entrance pupil in a design that takes advantage of all the surfaces being nearly "spherically symmetrical"<ref>[http://www.quadibloc.com/science/opt0203.htm John J. G. Savard, "'''Miscellaneous Musings'''"]</ref> to correct [[spherical aberration]], a significant problem in other types of [[reflecting telescope]]s<ref>[http://www.riverofstars.net/JSCAS/Starscan/Feb04.pdf Dmitri Maksutov: The Man and His Telescope]</ref>. |
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===Attribution=== |
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| ⚫ | In [[German-occupied Europe|German-occupied]] [[Holland]], Albert Bouwers submitted patents in February of 1941 for a similar wide field concentric meniscus telescope design (called a [[Albert Bouwers#Bouwers meniscus telescope|"Bouwers telescope"]]) that slightly predates Maksutov's<ref name=weasner>[http://www.weasner.com/etx/guests/mak/MAKSTO.HTM Evolution of the Maksutov design]</ref><ref name=bouwers1>Ian Ridpath, "Bouwers telescope", ''A Dictionary of Astronomy'', 1997 [http://www.highbeam.com/doc/1O80-Bouwerstelescope.html first sentence of article]</ref>. Bouwers original design differs from Maksutov's in that it used a purely concentric shaped meniscus corrector that was not [[achromatic]] |
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It was invented in 1940 <ref name=firefly/> war torn Europe by [[Albert Bouwers]] in [[The Netherlands]] and Russian optician Dmitri Maksutov in 1944. <ref name=firefly> ''Firefly astronomy dictionary |
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By John Woodruff'' page 135 [http://books.google.com/books?id=kX_DAEsOWssC&pg=PA135&dq=Albert+Bouwers&as_brr=3#v=onepage&q=Albert%20Bouwers&f=false Google Books]</ref> They both based there similar designs on an earlier concentric design, [[Bernhard Schmidt]]'s "[[Schmidt Camera]]".<ref name=weasner>[http://www.weasner.com/etx/guests/mak/MAKSTO.HTM Evolution of the Maksutov design]</ref> A. Bouwers made a prototype by August 1940 <ref name=king> ''The History of the Telescope'' By Henry C. King, page 360; [http://books.google.com/books?id=KAWwzHlDVksC&pg=PA360&dq=Bouwers+published+meniscus&lr=&as_brr=3#v=onepage&q=&f=false google books] </ref>, and submitted patents by February 1941. |
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Maksutov claimed to have come up with the idea of replacing the complex [[Schmidt corrector plate]] with an all spherical "meniscus corrector plate" while riding in in a train of refugees from Leningrad.<ref>[http://adsabs.harvard.edu/full/1950IrAJ....1...48A Armstrong, E. B., "'''Geometrical Optics and the Schmidt Camera'''", Irish Astronomical Journal, vol. 1(2), p. 48]</ref>. Maksutov is described as patenting his design in May <ref>[http://adsabs.harvard.edu/full/1950IrAJ....1...48A Armstrong, E. B., "'''Geometrical Optics and the Schmidt Camera'''", Irish Astronomical Journal, vol. 1(2), p. 48]</ref>, August, or October of 1941<ref>[http://www.telescopengineering.com/history/DmitriMaksutov.html Dmitri Maksutov: The Man and His Telescopes By Eduard Trigubov and Yuri Petrunin]</ref> and building a "Maksutov-[[Gregorian telescope|Gregorian]]" style proto-type in October 1941<ref>[http://www.telescopengineering.com/history/DmitriMaksutov.html Dmitri Maksutov: The Man and His Telescopes By Eduard Trigubov and Yuri Petrunin]</ref>. Maksutov came up with the unique idea using corrector made of a single type of glass with a slightly positive meniscus shape that departed from the pure concentric spherical symmetrical shape to correct chromatic aberration.<ref>[http://books.google.com/books?id=v7E25646wz0C&pg=PA202&lpg=PA202&dq=maksutov++bouwers+concentric+achromatic&source=bl&ots=glMQHo-0SU&sig=cYbi4I8wTiwO-LVyWikACT8Dshc&hl=en&ei=zu9dSpqiHtCFmQeH4-WCAQ&sa=X&oi=book_result&ct=result&resnum=7 "Astronomical optics" By D. J. Schroeder, page 202]</ref> |
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| ⚫ | In what soon became [[German-occupied Europe|German-occupied]] [[Holland]], Albert Bouwers submitted patents in February of 1941 for a similar wide field concentric meniscus telescope design (called a [[Albert Bouwers#Bouwers meniscus telescope|"Bouwers telescope"]]) that slightly predates Maksutov's<ref name=weasner>[http://www.weasner.com/etx/guests/mak/MAKSTO.HTM Evolution of the Maksutov design]</ref><ref name=bouwers1>Ian Ridpath, "Bouwers telescope", ''A Dictionary of Astronomy'', 1997 [http://www.highbeam.com/doc/1O80-Bouwerstelescope.html first sentence of article]</ref>. Bouwers original design differs from Maksutov's in that it used a purely concentric shaped meniscus corrector that was not [[achromatic]]<ref name=weasner> [http://www.weasner.com/etx/guests/mak/MAKSTO.HTM Evolution of the Maksutov design]</ref><ref name=bouwers1>Ian Ridpath, "Bouwers telescope", ''A Dictionary of Astronomy'', 1997 [http://www.highbeam.com/doc/1O80-Bouwerstelescope.html first sentence of article]</ref>, although it is also described as being identical to it in some sources. <ref name=bouwers1/> A later design used a cemented [[Doublet (lens)|doublet]] as a corrector shell to correct [[chromatic aberration]]<ref>[http://books.google.com/books?id=v7E25646wz0C&pg=PA202&dq=maksutov++bouwers&lr=#PPA202,M1 D. J. Schroeder, "Astronomical Optics", page 202]</ref>. Because of the similarity between the two designs and their close creation dates, these telescopes are sometimes referred to as "Bouwers-Maksutov" telescopes<ref>[http://books.google.com/books?id=OJrJrEJ-r9QC&pg=PA178&lpg=PA178&dq=%22bouwers+maksutov%22&source=bl&ots=YY2p6Rt03A&sig=bWQO3tg0cLlqjQg_MGHPteO0Glc&hl=en&ei=Rf7MSebsEdfVlQeE2JXICQ&sa=X&oi=book_result&resnum=10&ct=result Rudolf Kingslake, "A History of the Photographic Lens", page 178]</ref>. War time secrecy kept both designs under wraps. Maksutov's was published in 1944 in a paper entitled ''New Catadioptric Meniscus Systems''<ref name=telescopeeng> [http://www.telescopengineering.com/history/DmitriMaksutov.html Dmitri Maksutov: The Man and His Telescopes By Eduard Trigubov and Yuri Petrunin]</ref><ref name=mak1> Cambridge Encyclopedia Vol. 48 "Maksutov telescope - Invention and Design, Applications, Derivative Designs" (article hosted by from encyclopedia.stateuniversity.com)</ref> and Bouwers design was not published until after the war<ref>[http://adsabs.harvard.edu/full/1950IrAJ....1...48A Armstrong, E. B., "'''Geometrical Optics and the Schmidt Camera'''", Irish Astronomical Journal, vol. 1(2), p. 48]</ref>. |
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Similar independent meniscus telescope designs were also patented in 1941 by K. Penning<ref>[http://books.google.com/books?id=wrtFcUEIWTgC&pg=PA724&dq=maksutov+telescope#v=onepage&q=maksutov%20telescope&f=false Handbook of Optical Systems, Survey of Optical Instruments, by Herbert Gross, Hannfried Zügge, Fritz Blechinger, Bertram Achtner, page 806]</ref> and [[Dennis Gabor]] (a catadioptric non-monocentric design).<ref>[http://books.google.com/books?id=7qCtsFeF7lkC&pg=PA313&lpg=PA313&dq=Dennis+Gabor+maksutov&source=bl&ots=eJ_AzW8md-&sig=7mEyiRZ2oNGW0A81w6l23DS2JN4&hl=en&ei=46J0SozcO8Gptgey6syWCQ&sa=X&oi=book_result&ct=result&resnum=8#v=onepage&q=Dennis%20Gabor%20maksutov&f=false Lens design fundamentals, by Rudolf Kingslake, page 313]</ref> |
Similar independent meniscus telescope designs were also patented in 1941 by K. Penning<ref>[http://books.google.com/books?id=wrtFcUEIWTgC&pg=PA724&dq=maksutov+telescope#v=onepage&q=maksutov%20telescope&f=false Handbook of Optical Systems, Survey of Optical Instruments, by Herbert Gross, Hannfried Zügge, Fritz Blechinger, Bertram Achtner, page 806]</ref> and [[Dennis Gabor]] (a catadioptric non-monocentric design).<ref>[http://books.google.com/books?id=7qCtsFeF7lkC&pg=PA313&lpg=PA313&dq=Dennis+Gabor+maksutov&source=bl&ots=eJ_AzW8md-&sig=7mEyiRZ2oNGW0A81w6l23DS2JN4&hl=en&ei=46J0SozcO8Gptgey6syWCQ&sa=X&oi=book_result&ct=result&resnum=8#v=onepage&q=Dennis%20Gabor%20maksutov&f=false Lens design fundamentals, by Rudolf Kingslake, page 313]</ref> |
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===The Maksutov-Cassegrain=== |
===The Maksutov-Cassegrain=== |
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[[Image:Maksutov spot cassegrain.png|right|thumb|500px|Light path in a typical "Gregory" or "spot" '''Maksutov-Cassegrain'''.]] |
[[Image:Maksutov spot cassegrain.png|right|thumb|500px|Light path in a typical "Gregory" or "spot" '''Maksutov-Cassegrain'''.]] |
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Maksutov's design notes from 1941 explored the possibility of a 'folded' [[Cassegrain reflector|Cassegrain]]-type construction with a secondary silvered "spot" on the convex side of the meniscus facing the [[primary mirror]].<ref name=telescopeeng/> He thought this would create a sealed and ruggedized optical system suitible for use in schools<ref name=telescopeeng/>. John Gregory, a designer for [[Perkin-Elmer]] |
The Maksutov-Cassegrain was invented in 1957. <ref> http://www.wisegeek.com/what-is-cassegrain.htm ''What is Cassegrain?''] </ref> However, Maksutov's design notes from 1941 explored the possibility of a 'folded' [[Cassegrain reflector|Cassegrain]]-type construction with a secondary silvered "spot" on the convex side of the meniscus facing the [[primary mirror]].<ref name=telescopeeng/> He thought this would create a sealed and ruggedized optical system suitible for use in schools<ref name=telescopeeng/>. Yet, it would be John Gregory, a designer for [[Perkin-Elmer]] who developed a new meniscus design known as the '''Maksutov-Cassegrain''', based on idea. Gregory later published his design for two f/15 and f/23 telescopes in a 1957 issue of ''Sky and Telescope''. Commercial use of the design was explicitly reserved for Perkin-Elmer. Most Maksutovs manufactured today are this type of 'Cassegrain' design (called either a "Gregory-Maksutov"<ref>[http://books.google.com/books?id=hzpoQRh9QEQC&pg=PA46&dq=gregory-Maksutov&lr= James Mullaney, "'''A Buyer's and User's Guide to Astronomical Telescopes & Binoculars'''", page 46]</ref> or "Spot-Maksutov") that may use all spherical surfaces and has, as secondary, a small aluminized spot on the inner face of the corrector. This has the advantage of simplifying construction. It also has the advantage of fixing the alignment of the secondary and eliminates the need for a 'spider' that would cause diffraction spikes. The disadvantage is that, if all spherical surfaces are used, such systems have to have focal ratios above F15 to avoid aberrations<ref>[http://pyxiscamera.htohananet.com/Maksutov/Maksutov.html '''A Photovisual Maksutov Cassegrain Telescope''' - by Marc René Baril ''. "Although convenient, this design is limited to focal ratios above F15 unless an aspheric correction is applied to some element in the optical system"'']</ref> . Also a degree of freedom in correcting the optical system by changing the radius of curvature of the secondary is lost since that radius is the same as that of the rear meniscus face. Gregory himself, in a second, faster (f/15) design resorted to aspherization of the front corrector surface (or the primary mirror) in order to reduce aberrations. This has led to other designs with aspheric or additional elements to further reduce off-axis aberration.<ref name = " "> {{cite book |
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Names given to this design: |
Names given to this design: |
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Names given to this design vary depending national, regional, and chronological attribution. |
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;More general types |
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*Catadioptric telescope (for the overall design class including ''Schmidts'') |
*Catadioptric telescope (for the overall design class including ''Schmidts'') |
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*Meniscus telescope (for the design type including Bouwers, Maksutov, K. Penning, and Dennis Gabor) |
*Meniscus telescope (for the design type including Bouwers, Maksutov, K. Penning, and Dennis Gabor) |
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;For basic Maksutov design: |
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*Maksutov telescope |
*Maksutov telescope |
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*Bouwers-Maksutov telescope |
*Bouwers-Maksutov telescope |
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*Schmidt-Maksutov telescope <ref> Schmidt-Maksutov telescope. (2009). In Encyclopædia Britannica. Retrieved March 24, 2009, from Encyclopædia Britannica Online: http://www.britannica.com/EBchecked/topic/527793/Schmidt-Maksutov-telescope </ref> |
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;For Maksutov-Cassegrain's |
;For Maksutov-Cassegrain's |
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*Spot-Maksutov |
*Spot-Maksutov |
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*Gregory-Meniscus telescope <ref> [http://home.att.net/~jsstars/gregory/gregory.html The Gregory Meniscus Telescope ]</ref> |
*Gregory-Meniscus telescope <ref> [http://home.att.net/~jsstars/gregory/gregory.html The Gregory Meniscus Telescope ]</ref> |
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*Bouwers-Cassegrain |
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Other types of catadioptric Cassegrains include the [[Schmidt-Cassegrain telescope]], the [[Argunov-Cassegrain telescope]], and the [[Klevtsov-Cassegrain telescope]]. |
Other types of catadioptric Cassegrains include the [[Schmidt-Cassegrain telescope]], the [[Argunov-Cassegrain telescope]], and the [[Klevtsov-Cassegrain telescope]]. |
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Another type is the [[Maksutov-Newton]] <Ref> http://www.company7.com/orion/catadioptric/argo6.html, SkyWatcher http://www.skywatchertelescope.net/swtinc/product.php?id=147&class1=1&class2=104, http://www.cloudynights.com/item.php?item_id=701 </ref> |
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==References== |
==References== |
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Revision as of 19:19, 17 August 2009
The Maksutov is a catadioptric telescope design invented in the 1940s that employs a full diameter positive meniscus lens (commonly called a "corrector plate") to correct the problems of off-axis aberrations such as coma found in reflecting telescopes while also correcting chromatic aberration. The design is most commonly seen in a Cassegrain variation, with an integrated secondary, that can use all-spherical elements, thereby simplifying fabrication. The chief disadvantage of the design is that it does not scale up well to large apertures (>250 mm/10 inches), since the corrector plate rapidly becomes prohibitively large, heavy and expensive as the aperture increases – most commercial manufacturers usually stop at 180 mm (7 inches).
Invention
This telescope design uses a spherical primary mirror in conjunction with a positive meniscus spherical surfaced "meniscus corrector shell" at the entrance pupil in a design that takes advantage of all the surfaces being nearly "spherically symmetrical"[1] to correct spherical aberration, a significant problem in other types of reflecting telescopes[2].
Attribution
It was invented in 1940 [3] war torn Europe by Albert Bouwers in The Netherlands and Russian optician Dmitri Maksutov in 1944. [3] They both based there similar designs on an earlier concentric design, Bernhard Schmidt's "Schmidt Camera".[4] A. Bouwers made a prototype by August 1940 [5], and submitted patents by February 1941.
Maksutov claimed to have come up with the idea of replacing the complex Schmidt corrector plate with an all spherical "meniscus corrector plate" while riding in in a train of refugees from Leningrad.[6]. Maksutov is described as patenting his design in May [7], August, or October of 1941[8] and building a "Maksutov-Gregorian" style proto-type in October 1941[9]. Maksutov came up with the unique idea using corrector made of a single type of glass with a slightly positive meniscus shape that departed from the pure concentric spherical symmetrical shape to correct chromatic aberration.[10]
In what soon became German-occupied Holland, Albert Bouwers submitted patents in February of 1941 for a similar wide field concentric meniscus telescope design (called a "Bouwers telescope") that slightly predates Maksutov's[4][11]. Bouwers original design differs from Maksutov's in that it used a purely concentric shaped meniscus corrector that was not achromatic[4][11], although it is also described as being identical to it in some sources. [11] A later design used a cemented doublet as a corrector shell to correct chromatic aberration[12]. Because of the similarity between the two designs and their close creation dates, these telescopes are sometimes referred to as "Bouwers-Maksutov" telescopes[13]. War time secrecy kept both designs under wraps. Maksutov's was published in 1944 in a paper entitled New Catadioptric Meniscus Systems[14][15] and Bouwers design was not published until after the war[16].
Similar independent meniscus telescope designs were also patented in 1941 by K. Penning[17] and Dennis Gabor (a catadioptric non-monocentric design).[18]
Derivative designs
The Maksutov-Cassegrain
The Maksutov-Cassegrain was invented in 1957. [19] However, Maksutov's design notes from 1941 explored the possibility of a 'folded' Cassegrain-type construction with a secondary silvered "spot" on the convex side of the meniscus facing the primary mirror.[14] He thought this would create a sealed and ruggedized optical system suitible for use in schools[14]. Yet, it would be John Gregory, a designer for Perkin-Elmer who developed a new meniscus design known as the Maksutov-Cassegrain, based on idea. Gregory later published his design for two f/15 and f/23 telescopes in a 1957 issue of Sky and Telescope. Commercial use of the design was explicitly reserved for Perkin-Elmer. Most Maksutovs manufactured today are this type of 'Cassegrain' design (called either a "Gregory-Maksutov"[20] or "Spot-Maksutov") that may use all spherical surfaces and has, as secondary, a small aluminized spot on the inner face of the corrector. This has the advantage of simplifying construction. It also has the advantage of fixing the alignment of the secondary and eliminates the need for a 'spider' that would cause diffraction spikes. The disadvantage is that, if all spherical surfaces are used, such systems have to have focal ratios above F15 to avoid aberrations[21] . Also a degree of freedom in correcting the optical system by changing the radius of curvature of the secondary is lost since that radius is the same as that of the rear meniscus face. Gregory himself, in a second, faster (f/15) design resorted to aspherization of the front corrector surface (or the primary mirror) in order to reduce aberrations. This has led to other designs with aspheric or additional elements to further reduce off-axis aberration.[22]
Applications
Astronomical uses
The focal ratio of the Maksutov-Cassegrain design provides high powers and a narrower field of view. This makes them unsuitable for wide-field astrophotography but superb at lunar and planetary imaging. They are also very adept at imaging tightly packed formations such as globular clusters and at splitting double stars. Maksutov-Cassegrain telescopes have been sold on the amateur market since the 1950s. Most early models were small run prestige models that were very expensive. The mid-70s saw the introduction of mass-produced models by some of the major commercial manufacturers. More recently low-cost Russian and, lately, Chinese mass-production have pushed the prices down even farther. Today the design has become a popular choice for the amateur astronomer, if not a 'telescope for the masses', something unthinkable in the 60s when even a small Maksutov-Cassegrains such as the 'Questar 3.5' were quite expensive and within the reach of deep pockets only.
Industrial/Aerospace uses
The Maksutov-Cassegrain design has been used extensively in military, industrial, and aerospace applications. Since all of the optical elements can be permanently fixed in alignment and the tube assembly can be environmentally sealed the design is extremely rugged. That makes them ideal for tracking, remote viewing, and radar calibration/boresighting where instruments are subjected to severe environments and high g-forces.
Names
Names given to this design:
Names given to this design vary depending national, regional, and chronological attribution.
- More general types
- Catadioptric telescope (for the overall design class including Schmidts)
- Meniscus telescope (for the design type including Bouwers, Maksutov, K. Penning, and Dennis Gabor)
- For basic Maksutov design
- Maksutov telescope
- Bouwers-Maksutov telescope
- Schmidt-Maksutov telescope [23]
- For Maksutov-Cassegrain's
- Maksutov-Cassegrain telescope
- Gregory-Maksutov telescope [4]
- Spot-Maksutov
- Gregory-Meniscus telescope [24]
- Bouwers-Cassegrain
Other types of catadioptric Cassegrains include the Schmidt-Cassegrain telescope, the Argunov-Cassegrain telescope, and the Klevtsov-Cassegrain telescope.
Another type is the Maksutov-Newton [25]
References
- ^ John J. G. Savard, "Miscellaneous Musings"
- ^ Dmitri Maksutov: The Man and His Telescope
- ^ a b Firefly astronomy dictionary By John Woodruff page 135 Google Books
- ^ a b c d Evolution of the Maksutov design Cite error: The named reference "weasner" was defined multiple times with different content (see the help page).
- ^ The History of the Telescope By Henry C. King, page 360; google books
- ^ Armstrong, E. B., "Geometrical Optics and the Schmidt Camera", Irish Astronomical Journal, vol. 1(2), p. 48
- ^ Armstrong, E. B., "Geometrical Optics and the Schmidt Camera", Irish Astronomical Journal, vol. 1(2), p. 48
- ^ Dmitri Maksutov: The Man and His Telescopes By Eduard Trigubov and Yuri Petrunin
- ^ Dmitri Maksutov: The Man and His Telescopes By Eduard Trigubov and Yuri Petrunin
- ^ "Astronomical optics" By D. J. Schroeder, page 202
- ^ a b c Ian Ridpath, "Bouwers telescope", A Dictionary of Astronomy, 1997 first sentence of article
- ^ D. J. Schroeder, "Astronomical Optics", page 202
- ^ Rudolf Kingslake, "A History of the Photographic Lens", page 178
- ^ a b c Dmitri Maksutov: The Man and His Telescopes By Eduard Trigubov and Yuri Petrunin
- ^ Cambridge Encyclopedia Vol. 48 "Maksutov telescope - Invention and Design, Applications, Derivative Designs" (article hosted by from encyclopedia.stateuniversity.com)
- ^ Armstrong, E. B., "Geometrical Optics and the Schmidt Camera", Irish Astronomical Journal, vol. 1(2), p. 48
- ^ Handbook of Optical Systems, Survey of Optical Instruments, by Herbert Gross, Hannfried Zügge, Fritz Blechinger, Bertram Achtner, page 806
- ^ Lens design fundamentals, by Rudolf Kingslake, page 313
- ^ http://www.wisegeek.com/what-is-cassegrain.htm What is Cassegrain?]
- ^ James Mullaney, "A Buyer's and User's Guide to Astronomical Telescopes & Binoculars", page 46
- ^ A Photovisual Maksutov Cassegrain Telescope - by Marc René Baril . "Although convenient, this design is limited to focal ratios above F15 unless an aspheric correction is applied to some element in the optical system"
- ^ Rutten, Harrie (1988). Telescope Optics: Evaluation and Design. Richmond, Va: Willman-Bell. ISBN 0-943396-18-2.
{{cite book}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Schmidt-Maksutov telescope. (2009). In Encyclopædia Britannica. Retrieved March 24, 2009, from Encyclopædia Britannica Online: http://www.britannica.com/EBchecked/topic/527793/Schmidt-Maksutov-telescope
- ^ The Gregory Meniscus Telescope
- ^ http://www.company7.com/orion/catadioptric/argo6.html, SkyWatcher http://www.skywatchertelescope.net/swtinc/product.php?id=147&class1=1&class2=104, http://www.cloudynights.com/item.php?item_id=701
See also
(commercially produced models)