Why Minolta Rokkor lens on CANON EOS DSLR ?

My special thanks to Dave Kirby for translation in English.

Today, many people are wondering if it is worthwhile using old photographic lenses on modern digital cameras. In this page I will try to explain why this choice makes good sense and hopefully raise some interest and curiosity in all the other photographers out there. The current standards of digital photography are now geared to the production and use of only target autofocus lenses for 35mm and in some cases for APS-C format. Manual focus lenses, made with high-quality mechanics and opticals, are still produced by a few manufacturers (Zeiss, Leica, Nikon) but their costs are prohibitive.

So, why use Minolta MC/MD lenses on modern DSLR ?

There are five main reasons:

1 - QUALITY: Minolta has developed in the past (1965-1985) some wonderful 35mm cameras (like the SRT 101/303, XM/XE/XD/X700) and some wonderful Rokkor lenses to accompany them. Minolta Engineers showed (in 1972-73) some Rokkor lenses (the "MC Rokkor SI 24/2.8" and the "MC Rokkor 16/2.8 fisheye" in particular) as well as the "electronic" XM camera to Leica Engineers. Leica chose Minolta (read this article in PDF) for a partner in developing their "R System". During the '70s Minolta, Leica and Leitz shared their technologies to develop some SLRs like the Leica R3 (Minolta XE), Leica R4 (Minolta XD) as well as some 35mm lenses. Today, for example, you can find lenses like the Elmarit R 24/2.8 in the Leitz catalogue (the original 9/7 optical design of the Minolta MC Rokkor 24mm f2.8 SI) or the AF 16/2.8 fisheye in the Sony catalogue (the original optical design of the Minolta MC Rokkor 16/2.8 fisheye). With the great 11/8 optical design this was another lens that Minolta manufactured in the past for Leitz!

 

2 - COSTS:

2.1 - about Minolta MC/MD lens: with the advent of the new digital technology, these “precious ones” (prime) lenses are now cheap on the used market. Their prices are ridiculous compared to the corresponding lens in AF mount. Two examples: on ebay it is possible to buy the famous Minolta MC ROKKOR PG 50/1.4 for approximately $30/60, only a “small” fraction compared to the CANON EF 50/1.4 or the NIKON 50/1.4 or SONY AF 50/1.4 ! On ebay it is possible to buy the great Minolta MD 35-70mm f3.5 Macro for $30-50; this is a ridiculous price for a lens "equal to" the Leitz Vario Elmar R 35-70mm f3.5 (also the MD 70-210mm f4 and MD 75-200mm f4.5 was Minolta project and sold by Leitz as "Leitz Vario Elmar R 70-210 f4 and Vario Elmar R 75-200mm f4.5 "). Another example: the MC Rokkor 24/2.8 SI that today, usually, sell from less than 100$.

2.2 - about Canon EOS DSLR: some good and inexpensive DSLRs (with APS-C and Full Frame CMOS digital sensor) are now available on the used market like the EOS 300D/350D/400D/450D/1000D (6-12 Mpixel) and the more expensive 20D/30D/40D/5D (8-12 MPixel). RAW files generated from my EOS 20D, 450D and latest 5D (full frame) with Rokkor lenses show outstanding optical performance from 100 to 800 ISO.

 

3 - AVAILABILITY: - The market does not offer a DSLR with Minolta MC/MD mount. The solution here is inexpensive, reversible (see Technical details) and compatible with several EOS DSLR bodies (with APS-C, Full Frame and APS-H CMOS digital sensor).

 

4 - TECHNICAL CONSIDERATIONS: - From a purely technical point of view the CANON EOS DSLRs are the best cameras for modification. Why ... ?

Because three mandatory conditions occur and their are necessary and sufficient for adaption:

4.1 - optical condition: the difference between the CANON EF's lens register (44mm) and the Minolta MD's lens register (43.5 mm) is minimal (only 0.5mm) compared to the register difference between lenses by other manufacturers: Sony (44.50mm), Nikon (46.50) and Pentax (45.46mm). Again... why CANON ? Because Rokkor lens have optical register that is shorter than all other one, so it is better to perform the adaption using the DSLR with the closest register to Minolta MD, i.e. the CANON DSLRs.

4.2 - mechanical condition: The CANON EF bayonet has a larger diameter than the Minolta MC/MD (SR) bayonet. The geometry of the CANON's mirabox (the area below the EF flange in particular) is compatible with the "shape" of Minolta MD lens mount.

4.3 - mechanical condition: the base of the CANON EF's mirror box is constructed such that the Minolta MC/MD lens, once mounted on the EOS-MD flange, does not interfere with the EOS mirror movement (this is expecially true for APS-C DSLR while for Full Frame DSLR the mirror need to be shaved a bit) and with other parts inside the mirabox. Note: this condition is not true for SONY DSLR and for this reason the SONY-MD flange is not possible to make !

 

5 - THE FIFTH ELEMENT: - In december 2006 I read two articles about optical physic for 35mm lens. I'm a Minolta fan and an amateur photographer with a large range of Rokkor lens. At the beginning of 2007, in January, I bought a used EOS 300D and began to think...Three years later, on 2010, I designed a new version of the EOS-MD flange for Canon EOS 5D.

... and the following image shows the results !

My first CANON EOS 300D (Digital Rebel) with the EOS-MD flange type 1 (optical register 43.5mm - Minolta MC/MD mount).

 

My first CANON EOS 5D (Full Frame) with the EOS-MD flange type 3 (optical register 43.5mm - Minolta MC/MD mount).

Minolta MD lens will have now a GREAT opportunity to be used on CANON DSLRs.

 

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