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Review: Minolta MC W Rokkor SI 28mm 1:2.5

Minolta MC W Rokkor SI 28mm 1:2.5 (“Hills&Valleys”/”Knurled” design or MC II by collectors classification) lens review.

A very popular lens often mentioned in recommendations for someone who is looking for wide-angle tools.

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 an 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.

MCC2825__exterior_679.jpg

Minolta MC W Rokkor SI 28mm f/2.5 parameters:

# in minolta.eazypix.de index 43
Name engraved on lens MC W.ROKKOR-SI
f[mm] 28
A max [1/f] 2,5
A min[1/f] 16
Lens design [el.] 9
Lens design [gr.] 7
Filter thread Ø front(rear)[mm] 55
Lens Shade screw-in
closefocus[m/ft] 0.5/1.5
Dimension Ø x length [mm] 64×61
Weight[g] 340
Year 1970
Style MC II
Code No. (ROKKOR-X) or Order No. 607-018
Notes
Floating elements NO
Aperture blades number 6
Average international price (sold items) 2020: USD 30-50
Reviewed Lens SN: 1561256

The lens has three reincarnations – MC I, MC II, and MC III (by popular collectors classification). This revied “Hills & Valleys” or “Knurled” design is MC II – the second generation that was born in 1970. All released lenses with parameters 28mm F2.5 by Minolta are radioactive. If my information is correct, the Minolta produced for 35mm cameras only two lens models which contain active elements in the glass – this 28/2.5 and 58/1.2 (reviewed already in non-radioactive version). The 28/2.5 hasn’t non-radioactive versions but from my point of view the level of activity is low and if to follow simple rules (like not to eat yellow snow… the yellow glass I mean. But yellow snow also in this list…) everything will be fine. I recommend to google more about radioactivity if you are worried. It seems to me that this trait adds a few scores for the popularity of this lens – it makes it a little unique and dangerous, so, only real rebels and cool guys can use it.

The reviewed copy has the easy visible yellow-tint on the back lens – it’s a result of radioactive decay. The color can be easy fixed with ultraviolet lamp (or sun-bath) but I prefer to leave it because two reasons, firstly I wanted to check how easy it can be fixed with auto-WB in digital editors, secondly the keeping this tint untouchable may turn the lens into good example which demonstrates radioactive effect on a glass if such example will be needed in future, for today this is only one radioactive lens which is available for me.


Lens exterior:

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

On camera Minolta SR-T101:


Sharpness – close distance:

Test description: target is a 10×15 cm picture (printed, glossy photo paper), fixed on the wall by scotch. Distance – 1.7m. 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 3 times for every target position on all apertures from fully opened up to F16, ISO-200, 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. Main idea – to exclude the field curvature affect on so close distance. Of course, I can’t be absolutely accurate, but test results looks correct.

Finally, pictures were converted from ARW-files in Capture One with default settings (Some single files have a slight light correction, for better visual convenience in comparison), then cropped for 300×200 px elements, combined into diagrams and exported into JPEG-files

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

Mayuri Shiina 32 2print.png

Scene preview:

MCC2825__b_res_close_previewNEW.jpg

Test results:

MCC2825__c_res_close.jpg


Sharpness – 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-50. 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 (files have a slight light and color correction, for better visual convenience in comparison), then were cropped for 300×200 px elements, combined into diagrams and exported into JPEG-files.

Scene preview:

MCC2825__e_far_preview.jpg

Test results:

MCC2825__e_res_far.jpg


Vignetting:

(frames scaled – 300×200)

MCC2825__f_vignettingNEW.png


Geometric distortion:

(frame scaled 1200×800)

MCC2825_geometry_67.jpg


Coma aberrations:

(100% crops – 300×200)

MCC2825__h_coma_aberr_.jpg


Chromatic aberrations:

(100% crops – 300×200)

MCC2825__i_chrome_aberrNEW_.png


Long distance bokeh:

Test#1:

Test conditions: lens was focused on minimal distance 0.5m, houses were fixed in infinity distance on the ground.

Such scenes can’t be meet often, so this is a demonstration of extreme conditions. In most cases of real-life photography, the blur level will be less, see the next Test#2.

(frame scaled 1200×800)

MCC2825__k_bokeh_far_min_0_5m_NEW.png

Test#2:

Test conditions: lens was focused on 1m – ‘portrait distance’, houses were fixed in infinity distance on the ground.

(frame scaled 1200×800)

MCC2825__k_bokeh_far_mid_1_0m_NEW.png


Light dots long distance bokeh:

Test #1

Test conditions: lens was focused on to minimal distance 0.5m, lights were fixed in more than 200m.

Such scenes can’t be meet often, so this is a demonstration of extreme conditions. In most cases of real-life photography the blur level will be less – see Test #2.

(frame scaled 1200×800)

MCC2825__m_dots_far_1min_0_5m__NEW.png

Test #2

Test conditions: lens was focused on 1m – ‘portrait distance’, houses were fixed in infinity distance on the ground.

(frame scaled 1200×800)

MCC2825__m_dots_far_2mid_1_0m_NEW.png


My overall conclusion about the Minolta MC W Rokkor SI 28MM F/2.5:

AvatarReview_MCC2825.png

Instead of other lenses from the era of “full metal jackets” this lens, not just a simple “steel&glass” but “steel&glass&radioactivity” so it is a treasure for anti-plastic rebels and a nice training tool for the preppers. Of course, it’s not the only advantage.

Seriously, it has low aberrations and nicely fixed geometric distortion. I’m not a connoisseur of bokeh from wide-angle lenses but test samples demonstrate that this lens has a pleasant bokeh which may be successfully used for a herbs/flower photography or subject photography, etc.

About the sharpness: the lens is really sharpened and provides enough good resolution over the frame from F5.6 (F8.0 is better of course) – an amazing result for wide lenses. No doubts that it is the best 28 lens from the “steel&glass” series. I can’t say that this is a gem, but it stays on position right after fantastic New-MD 28mm F2.

What about radioactivity – it seems to me as a disadvantage, not because of influence for health – just follow simple rules and everything will be fine, but because of the fact of the existence of these rules (and of course not because of yellow tint which can be easily fixed).

The lens can be recommended by it’s IQ, but what about the disadvantages – it’s a personal choice of a photographer.


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