Gerald
Joined: 25 Mar 2014
Posts: 1196
Location: Brazil
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 Posted: Thu Apr 17, 2014 1:38 pm Post subject: LENSES: Facts and Fallacies - Part IX |
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Gerald wrote:
The mirror lenses were conceived to address the two major shortcomings of traditional telephoto: excessive size and weight. Maybe the Russian MTO-500 was the first example of a mirror lens with commercial success. In the seventies, virtually every major lens manufacturers had at least one objective mirror to sell. However, with time mirror lenses lost popularity, and today the new mirror lenses for sale are little more than toys.
One of the problems with old mirror lenses is that the film on the mirror degenerates with time, making the lens practically unusable. Even when new, mirror lenses suffer from some intrinsic problems: relatively low contrast, fixed aperture and bokeh with rings. Nevertheless, there are many people who enjoy the mirror lens "character". The late Herbert Keppler, for example, was famous for his collection of mirror lenses.
Once, NASA commissioned Vivitar to design a special mirror lens, in which the space between the mirrors was filled with a thick glass lens. The goal was to make a very compact lens for its focal length. The "solid cat" eventually came to the civilian market as a Series 1 model, but success was relatively small, because the lens was expensive and very heavy. Obviously, weight was not a problem when the lens was used in space without gravity.
to be continued...
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If raindrops were perfect lenses, the rainbow did not exist.
Last edited by Gerald on Sun Mar 05, 2017 5:43 pm; edited 1 time in total |
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visualopsins
Joined: 05 Mar 2009
Posts: 10531
Location: California
Expire: 2025-04-11
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| Posted: Sat Apr 19, 2014 8:10 pm Post subject: Re: LENSES: Facts and Fallacies - Part IX |
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visualopsins wrote:
| Gerald wrote: |
| ... Obviously, weight was not a problem when the lens was used in space without gravity. |
Getting the lens into space, however, ... 
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Cameras: Sony ILCE-7RM2, Spotmatics II, F, and ESII, Nikon P4
Lenses:
M42 Asahi Optical Co., Takumar 1:4 f=35mm, 1:2 f=58mm (Sonnar), 1:2.4 f=58mm (Heliar), 1:2.2 f=55mm (Gaussian), 1:2.8 f=105mm (Model I), 1:2.8/105 (Model II), 1:5.6/200, Tele-Takumar 1:5.6/200, 1:6.3/300, Macro-Takumar 1:4/50, Auto-Takumar 1:2.3 f=35, 1:1.8 f=55mm, 1:2.2 f=55mm, Super-TAKUMAR 1:3.5/28 (fat), 1:2/35 (Fat), 1:1.4/50 (8-element), Super-Multi-Coated Fisheye-TAKUMAR 1:4/17, Super-Multi-Coated TAKUMAR 1:4.5/20, 1:3.5/24, 1:3.5/28, 1:2/35, 1:3.5/35, 1:1.8/85, 1:1.9/85 1:2.8/105, 1:3.5/135, 1:2.5/135 (II), 1:4/150, 1:4/200, 1:4/300, 1:4.5/500, Super-Multi-Coated Macro-TAKUMAR 1:4/50, 1:4/100, Super-Multi-Coated Bellows-TAKUMAR 1:4/100, SMC TAKUMAR 1:1.4/50, 1:1.8/55
M42 Carl Zeiss Jena Flektogon 2.4/35
Contax Carl Zeiss Vario-Sonnar T* 28-70mm F3.5-4.5
Pentax K-mount SMC PENTAX ZOOM 1:3.5 35~105mm, SMC PENTAX ZOOM 1:4 45~125mm
Nikon Micro-NIKKOR-P-C Auto 1:3.5 f=55mm, NIKKOR-P Auto 105mm f/2.5 Pre-AI (Sonnar), Micro-NIKKOR 105mm 1:4 AI, NIKKOR AI-S 35-135mm f/3,5-4,5
Tamron SP 17mm f/3.5 (51B), Tamron SP 17mm f/3.5 (51BB), SP 500mm f/8 (55BB), SP 70-210mm f/3.5 (19AH)
Vivitar 100mm 1:2.8 MC 1:1 Macro Telephoto (Kiron)
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Gerald
Joined: 25 Mar 2014
Posts: 1196
Location: Brazil
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| Posted: Sat Apr 19, 2014 10:01 pm Post subject: |
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Gerald wrote:
| sichko wrote: |
From the second copied page ...
| Quote: |
The Depth of Field Controversy : Wide angle vs. Tele :
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All other things being equal, depth of field (d.o.f.) depends only upon image size and aperture diameter.
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... aperture diameter should read relative aperture or f-number |
Yes, the author made a slip. However, note that he mentioned that both pictures were taken with the same F-number F5.6.
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If raindrops were perfect lenses, the rainbow did not exist. |
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