Minolta "Super Rokkor" 5cm F2.8- a Derivative of the Cooke Triplet

Discussion in 'Collector's Corner' started by Brian, Apr 29, 2017.

  1. Brian

    Brian Super Moderator Subscribing Member

    Apr 3, 2013
    Minolta Leica Thread Mount lenses are uncommon, very little written about them. I started picking them up ~2 years ago, the 5cm F2 "Summitar" formula lens, then the 8.5cm F2.8, 4.5cm F2.8, and 11cm F5.6- a "Japanese Mountain Elmar" of sorts. Today I added the 5cm F2.8- also a 3-1-1 formula lens. This one uses 40.5mm accessories, is much longer than the 4.5cm F2.8. Minolta held to the 32x24 standard much longer than Nikon, Canon, and most other Japanese camera companies. The 45 made sense for that format. Once they pushed out to the 36x24 frame, the 50 seems to have replaced the earlier lens.

    The 45/2.8, 50/2.8, and 85/2.8 are as far as I know, reading Neblette and Kingslake- the only "3-1-1" configurations made. I took a 45/2.8 apart: the front two groups are stamped in a single metal fixture, the rear element is a positive element that forms an image on its own. The front two groups combined have a negative focal length, like a Cooke Triplet and a Tessar.

    The Minolta Super-Rokkor F2.8 lenses started with a Cooke Triplet (1-1-1, "positive/Negative/Positive focal lengths) and split the front element into a cemented Triplet, providing a much faster F2.8 than is commonly seen. Most F2.8 Tessars of that day are quite soft when used wide-open, to the point that the F3.5 Zeiss Tessar has a much better reputation than the faster F2.8. The front element of the F2.8 Tessar is a thick piece of glass, "strong power" optic. I believe the optical engineers for Minolta decided to split the strong front element into the triplet, using elements of lesser power, making aberrations easier to correct. Manufacturing a triplet is expensive, doing so for "just" an F2.8 lens- maybe that's why this formula was not used by others.

    The Super-Rokkors are quite good when used wide-open, edge to edge. The Super-Rokkors are not as plentiful in the US, and often the asking price on Ebay is too high. But with some patience, can be found at reasonable prices. In my opinion, they are the best F2.8 Triplets out there- better than the vintage 1-1-2 (4 elements in 3 groups, the rear element of the Cooke triplet made into a doublet) Tessars and Xenars. I will be doing some more informal tests, have an original Contax mount 5cm F2.8 Tessar, slightly later version- both Contax mount, in adapters; A Xenar Special 5 element in 4 group 5cm F2.8 adapted to Leica mount, and a good I26m. Will be an interesting shoot-out of the Moderate speed lenses.

    The 5cm F2.8 Super-Rokkor, wide-open on the M9:

    34189779572_f4ef3e3ea5_b. Minolta 5cm F2.8, wide-open by fiftyonepointsix, on Flickr

    33537244623_2c6dde3724_b. Minolta 5cm F2.8, wide-open by fiftyonepointsix, on Flickr

    33537248393_a45e2e55c5_b. Minolta 5cm F2.8, wide-open by fiftyonepointsix, on Flickr

    33537246923_d704940c27_b. Minolta 5cm F2.8, wide-open by fiftyonepointsix, on Flickr

    Above are quick tests- was late in the day. More coming in the next few weeks.
     
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  2. radi(c)al_cam

    radi(c)al_cam Leica Place Regular

    64
    Oct 20, 2016
    Alexander
    And in Europe, they're not just scarce, they're outright rarities, unfortunately :(
     
  3. Brian

    Brian Super Moderator Subscribing Member

    Apr 3, 2013
    Ebay draws the yardsales of the world together...
     
  4. Bar8barian

    Bar8barian New to Leica Place

    5
    Jan 23, 2016
    "Sceptred Isle"
    Thank you Brian, a very interesting write-up on these lenses.
    The Minolta LTM lenses are very good lenses and were very neglected.I use a 5cm f1.8 Super-Rokkor and it is a very fine performer. This lens
    was produced for the rare Minolta IIB camera, which was the last of the Minolta LTM cameras and only produced for about 2 years.
    From what I can gather the lens itself was never marketed as a separate item and was only available with the Minolta IIB camera.
    The Minolta IIB was never marketed in the U.S.
    This lens has now become highly sought after and unfortunately prices have risen due to scarcity.
    I originally found very little information on the Minolta LTM lenses on the web and especially the 5cm f1.8 Super-Rokkor, so I started a thread
    on Rangefinder Forum back in 2012 to try and get more information about these lenses.
    See:- CHIYODA KOGAKU (MINOLTA) 5cm f1.8 Super Rokkor LTM fitting - Rangefinderforum.com
     
    Last edited: May 14, 2017
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  5. Brian

    Brian Super Moderator Subscribing Member

    Apr 3, 2013
    A very informative thread on RFF.

    I am keeping an eye open for the 5cm F1.8, interesting to read it is 6 elements in 5 groups. The 55/1.8 and 58/1.4 SLR lenses were also 6 elements in 5 groups. Not having much luck in finding a diagram for the LTM lens, did find the 58/1.4. It is a 1-1-1-2-1 layout.

    My Nikon S4, never imported to the US, has a distance scale in feet as it was sold through the PX system in Japan. Maybe 1 in 10 S4's are in feet. I have a Nikon SP in meters, sold in Europe. Not many of those, either.
     
    Last edited: May 14, 2017
  6. Brian

    Brian Super Moderator Subscribing Member

    Apr 3, 2013
    Also note that the Minolta 55/1.8 and 55/1.7 SLR lenses were "PF", 6 elements in 5 groups. Hard to find the optical diagram for these, may pick up one at the next photorama show.
     
  7. Bar8barian

    Bar8barian New to Leica Place

    5
    Jan 23, 2016
    "Sceptred Isle"
    Brian,
    This is the only diagram that I have found of the element make-up of the 5cm f1.8 Super-Rokkor LTM that was illustrated in a Japanese camera magazine.
    It is a 1-1-1-2-1 layout.
    5cm f1.8 Super-Rokkors in LTM are mainly found scaled in metres. Luckily I managed to acquire a "mint" copy scaled in "FEET".
    I presume that Minolta35-IIB's with metre scaled 5cm f1.8 Super-Rokkor lenses were for the Japanese domestic market or metric based Continental Europe. My lens scaled in feet must have passed through the "PX" system for the U.S or another non-metric based country such as Australia/New Zealand/United Kingdom.

    See attachment :- super-rokkor-50-1.8.
     
    Last edited: May 14, 2017
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  8. Brian

    Brian Super Moderator Subscribing Member

    Apr 3, 2013
    It's the same block diagram as the early SLR 55mm F1.8 and 58mm F1.4 and kept for the much newer 50/1.7. Anyone shooting with a Mirrorless camera: the 55/1.8 goes for ~$25 these days. I made an RF coupling for my later Minolta MC series 50/1.4. The Minolta MD 50/1.7 is also a 6 element in 5 group lens... dirt cheap. My Minolta Hi-Matic 9 has a 45/1.7 PF on it: very, very sharp and I've had it since 1969.

    31038941622_06496a0a9e_b. minolta by fiftyonepointsix, on Flickr

    So- same optical layout as the 5cm F1.8, which I still want! But- will probably get the 50/1.7 and hack it.
     
  9. Brian

    Brian Super Moderator Subscribing Member

    Apr 3, 2013
    Found it in Neblette, 1965 edition.

    21763547755_943b1363c6_o. lens_formulas_65a by fiftyonepointsix, on Flickr

    Minolta lenses under diagram "G" are for the RF, those under "O" are for the SLR. They kept the same basic design.
     
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  10. Bar8barian

    Bar8barian New to Leica Place

    5
    Jan 23, 2016
    "Sceptred Isle"
    Very interesting information on all these lenses Brian,Many thanks.
     
    • Appreciate Appreciate x 1