Lens review: Chiyoda Kogaku Super Rokkor 1:1.8 f=5cm (Minolta) Japan LTM/LSM/m39

In this review, only the technical properties of the lens are investigated. Artistic abilities will be tested in the future, in a separate article.

After getting a new lens, I always take a few technical shots to understand its strengths and weaknesses – usually it helps me a lot to start using unknown lens with much less of doubt. One day I decided that my data might be interesting for someone else and this site has been made.

MinoltaLTM5018ext_26

Chiyoda Kogaku Super Rokkor 1:1.8 f=5cm Leica mount parameters:

Name engraved on lens 5cm f/1.8 Chiyoda Kogaku Super Rokkor
f[mm] 50
A max [1/f] 1.8
A min[1/f] 22
Number of blades 10
Lens design [el.] 6
Lens design [gr.] 5
Filter thread Ø front(rear)[mm] 46
closefocus[m] 1
Max. diameter[mm] 54
Lengh min/max [mm]  44 – 41
Weight[g] 260

Additional information:

  • This lens was introduced in May 1958 (with new Minolta 35 Model IIB camera)
  • This lens has an absolutely optically the same version for Minolta Super A mount.
  • It has Minolta Achromatic Coating
  • It has Planar (Double Gauss) -like optical design
  • This tested lens arrived directly from Japan
  • Optical and mechanical condition of this copy is very nice. There is nothing which can affect the images
  • There are two ranges of serial numbers: first is like  120xxxx with total amount of released lenses about 7500 units, and second 130xxxx with 3000 units are produced. No really differences between this versions except serial numbers diapasons has been found
  • Total amount of released lenses is about 10500, it means that lens can be called as rare. But not very much actually, right now I see four lots on eBay, so, word ‘expensive’ in description is better  appropriate than ‘rare’
  • Reviewed lens has serial 1200154, and for today it is earliest of all known copies in collectors lists (Many thanks to Andrea Aprà for details). Do you feel how the price of this copy grows after these words? (It’s a joke)
  • One more: the feeling of this lens is better than it can be expected of the rangefinder lenses from later 1950-x – because it isn’t so ‘aluminum’ as some others. It isn’t the same design as Serenars from 1951-1953 but it heavy too. This body looks like a father of first Minolta SR-Rokkors – very solid, and a lot of people are fans of such things

Lens exterior:

(Please, forgive me the dust on the lens, I never have the patience to clean objects for close-up photo sessions)


Lens code name – Mai Kawakami  川神 舞

Mai Kawakami (川神 舞 Kawakami Mai) is one of the main characters of the Musaigen no Phantom World series. She is a second-year high school student at Hosea Academy, who has a special ability in which she fights the Phantoms along with her friends as a Phantom Hunter of Team E.


Resolution – close distance:

Test description: target is a 10×15 cm picture (printed, glossy photo paper), fixed on the wall by scotch. Distance is 1.8m. Camera Sony A7II (24mpx, full frame) was fixed on the tripod and managed remotely with computer display as a viewfinder. All groups of shots were repeated 9 times for every target position on all apertures from fully opened up to F16, ISO-100, WB – same for all shots. SteadyShot – OFF. Focus was manually corrected for each shot. After all needed shots have been taken for one target position – I moved  the target to the next place.

test_scene_view300x200

Main idea – to exclude the field curvature affect on so close distance.

Of course, I can’t be absolutely accurate, but so many repeats of shots – 4 for corners, 2 for long side, 2 for short side are giving me insurance that test results are correct.

Finally, pictures were converted from ARW-files in Capture One with default settings,  cropped for 300×200 px elements, combined into diagrams and exported into JPEG-files.

Scene preview:

MinoltaLTM5018_scene_preview

Original target image (printed in horizontal orientation on 10cm X 15cm glossy photo paper)

689426

Test results (selected version, easy to compare – 4 positions):

MinoltaLTM5018__SHORT

Test results (full version – all 9 positions):

MinoltaLTM5018_FULL


Resolution – long distance:

Test description: Camera Sony A7II (24mpx, full frame) was fixed on the tripod and managed remotely with computer display as a viewfinder. Targets (buildings) were fixed by gravity power on the distances in more than 200 meters. All shots have been taken with apertures from fully opened up to F16. ISO-100. Shutter Speed – depends on light (camera A-mode), WB – fixed and the same for all shots. SteadyShot – OFF. Focus was manually corrected for each shot to exclude focus-shift affect.

Finally, pictures were converted from ARW-files in Capture One with default settings, were cropped for 300×200 px elements, combined into diagrams and exported into JPEG-files.

Scene preview:

Test results:


Vignetting:

(frames scaled – 300×200)

Chiyoda5018__Vignetting


Geometric distortion:

(frame scaled 1200×800)

MSR5018geometry


Coma aberrations:

(100% crops – 300×200)

Chiyoda5018_coma_aberr_

One more image crop from picture made with F2.8 can help to understand the dynamic of coma aberrations changing:

MinoltaLTM5018coma_2_8_64


Chromatic aberrations:

(100% crops – 300×200)


Close distance bokeh:

Test conditions: lens was focused on to minimal distance 1m, plants were fixed in 3m distance from camera in front of the window with bright light from outside.

(frame scaled 1200×800, bokeh covers the frame partially)

MSR5018_bokeh_close_3crops


Long distance bokeh:

Test conditions: lens was focused on half distance on the scale (2m), houses were fixed in infinity distance on the ground.

(frame scaled 1200×800)

Chiyoda5018_bokeh_far_5crops


Light dots bokeh:

Test conditions: lens was focused on to minimal distance 1m, diodes were  fixed in 3m distance at the dark background.

Note: a lot of similar tests with another 50mm lenses for same or close conditions are presented on the site, so you can compare easily. Please, read other articles.

(frame scaled 1200×800)

MSR5018_dots_close_4crops


Light dots long distance bokeh:

Test conditions: lens was focused on to minimal distance 1m, lights were fixed in more than 200m. Such scenes can’t be meet often, so this is demonstration of extreme conditions. In most cases of real life photography the blur level will be less.

(frame scaled 1200×800)

Chyioda5018_Dots_far


Another resources with tests and reviews:


My overall conclusion about the Chiyoda Kogaku Super Rokkor 1:1.8 f=5cm:

AvatarPlankMinoltaLTM5018

I’ve spend about a month with this lens and few other competitors from 1950-1960 LTM league and got a few minds:

  • This lens has a chance to be called as one of the best LTM fifty by technical abilities, as it has been noticed on some forums.
  • Any 50mm SLR lens from 1970-x or later would be better in technical aspects with about 10x price difference. Don’t try to compare it with modern SLR lenses by technical aspects – this Super Rokkor doesn’t have a chance to be better from a sharpness or aberrations point of view.
  • It is popular target among of collectors because it’s rarity. It means that this lens is usually overpriced on auctions.
  • If some photographer with mirrorless camera by unknown reason want to switch his DSLR-lens for Leica -like lens and to get the closest result for modern lenses by technical aspects – this lens would be the good choice.
  • For me this Chiyoda looks really as ‘bokeh-monster’ – rangefinder style look is greatly presented on the photos. Very artistic lens.
  • This lens would be nice in role of single universal lens in the photographer’s bag.
  • Lens is ready for portraits wide opened, became very good on F4, for landscapes it need to be closed to F8.
  • Difference between F1.8 and F2.0 can be seen with microscope only.
  • I didn’t present any flare-resistance tests yet, it is in plans for the future, but in real photography I’ve felt that lens-shade is needed.
  • On close distances corners are sharper than middle zone on the photos. On the long distance all as usual. Such behavior can be meet for some other rangefinder lenses.

Finally: of course this lens is strongly recommend, but in case if it can be found for reasonable price.


This lens took part in the battles:

50mmLTM_Serenars_MSR_Battle__Avatar