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All eight Minolta 28mm Rokkor computations compared
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PostPosted: Sun Apr 09, 2017 7:48 pm    Post subject: All eight Minolta 28mm Rokkor computations compared Reply with quote
Over the weekend i have re-done my earlier (not published) Full Frame tests of 28mm Rokkors. They confirmed what i already found in 2015; now i hav published a selection of the results:

http://artaphot.ch/minolta-sr/objektiv-vergleiche/506-minolta-mc-md-28mm-lenses-on-24mp-full-frame

While such a test is far from complete, and not a detailed review, it may give some useful information.

Usually i did test 2-3 copies of each lens design, often in different barrels. Whenever i tested several copies of the same design, the results were identical. I am, therefore, confident that the results shown here are representative and reliable.

All eight known computations are described:

* 3.5/28mm [7/7], 67mm filter (AR / MC-I)
* 3.5/28mm [7/7], 55mm filter (MC-I / MC-II / MC-X)
* 3.5/28mm [5/5] (MC-X / MD-I / MD-II / MD-III)
* 2.8/28mm [7/7] (MC-X / MD-I / MD-II / MD-III)
* 2.8/28mm [5/5] (MD-III)
* 2.5/28mm [9/7] (MC-I / MC-II / MC-X)
* 2/28mm [10/9], floating element (MC-X / MD-I / MD-II)
* 2/28mm [9/9], floating element (MD-III; same optical formula as later AF 2/28mm)

Stephan


PostPosted: Sun Apr 09, 2017 9:28 pm    Post subject: Reply with quote
I rarely use my Rokkor SG 28 / 3.5, simply because I use my faster Vivitar S1. 28 / 1.9 when I want a Minolta 28, I guess if the Vivitar had a Pentax mount I'd use the Rokkor. But looking at your tests, I shall be making the effort to try the Rokkor. Like 1 small


PostPosted: Sun Apr 09, 2017 10:22 pm    Post subject: Reply with quote
Like 1 Like 1 Like 1 great work!!


PostPosted: Mon Apr 10, 2017 12:01 am    Post subject: Reply with quote
Stephan , I think there are many variations in the samples.
My 28 2.5 is clearly better than yours. It is very good indeed and sharp in the corners at f5.6. I think that my copy was never used.
It is largely superior to my MC 28 3.5 and also better than my MD 28 3.5 (5/5)
My recently acquired MD 28 2.8 (7/7) is a lemon .
All tested on A7.


PostPosted: Mon Apr 10, 2017 3:58 am    Post subject: Reply with quote
memetph wrote:
Stephan , I think there are many variations in the samples.
My 28 2.5 is clearly better than yours. It is very good indeed and sharp in the corners at f5.6. I think that my copy was never used.
It is largely superior to my MC 28 3.5 and also better than my MD 28 3.5 (5/5)
My recently acquired MD 28 2.8 (7/7) is a lemon .
All tested on A7.

Interesting - could you provide some images as well?
Maybe i'll publish the results from all tested lenses, as i've done lon time ago with four Minolta AF 28-135mm lenses (which were behaving nearly identical as well):
http://artaphot.ch/minolta-sony-af/objektiv-vergleiche/230-310-minolta-af-4-4528-135mm-sample-variation

Up to now i've found very little sample variation with Minolta MC/MD lenses. Only two exceptions were one MC-II 2.8/135mm and one 4.5/75-200mm zoom.

Stephan


PostPosted: Mon Apr 10, 2017 5:56 am    Post subject: Reply with quote
We must never forget that many of these lenses are quite old, they may have been dropped, opened, cleaned or whatever happened to them over the years. It might just be very possible that copy variation due to the mentioned factors is the reason for different opinions on performance.

Nevertheless: i really like your efforts and your website, it's a great resource!
You might just have bumped the prices on that final version of the 2/28 lens though.... Wink


PostPosted: Mon Apr 10, 2017 9:04 am    Post subject: Reply with quote
Excellent work Like 1 small Like 1 small Thank you! . ..as usual.

...actually guilty!... as I spent much more money than I expected buying old Minolta lenses reading your website...

No regret though...

Last edited by Antoine on Mon Apr 10, 2017 7:06 pm; edited 1 time in total


PostPosted: Mon Apr 10, 2017 9:14 am    Post subject: Reply with quote
Excellent test!


PostPosted: Mon Apr 10, 2017 5:12 pm    Post subject: Reply with quote
TrueLoveOne wrote:
We must never forget that many of these lenses are quite old, they may have been dropped, opened, cleaned or whatever happened to them over the years. It might just be very possible that copy variation due to the mentioned factors is the reason for different opinions on performance.


Of course there are lots of problems when doing such "real" tests.

1) getting the lenses (they should look good from outside)
2) getting the adapters (i have about 5 Minolta adapters)
3) finding a good place
4) waiting for a nice, clear day and stable light conditions (usually one of those days that would be perfect for a paid job, BTW)
4) working quickly, yet without mistake
5) having an additional eye on potential thieves ... with all the lenses ready to be tested (if i'm working in town there are always some spectators ... and some of them didtry to rob me in the past)

Before doing any "real" test i usually do two or even three pre-tests to learn about the lenses. Some may be very good over most of the field, and drop suddenly in the very corner. Others may be good in the corners, and so-so in the field. Last but not least there's field curvature - and it is difficult to judge. For some users it's an annoying mistake, but in some conditions it can be a feature (if all other aberrations are well corrected). Like most testers, i do focus in the center, and i do consider field curvature as a mistake. And i do focus wide open, without re-focusing when stopping down (spherical aberrations can cause focus shift). And then - when the vintage lens is fast - you can focus on the red image, on the green image, on the blue image ... or somewhere in between: but where exactly??

During these pre-tests i usually check several samples of the same optical construction. Up to now, among several hundred primes tested, there there was one single prime lens (a Minolta MC-II 2.8/135mm) that was obvioulsy a "lemon"; all other double/triple/ ... /sevenfold (!) tested lenses did behave nearly identically (and i mean very very similar). - There is, for instance, an immediate and obvious difference between a Minolta AF 2.8/28mm and an AF 2/28mm lens, but no visible difference between several copies of the AF 2.8/28mm (or several 2/28mm lenses). I must admit that i've tested only Canon/Konica/Minolta/Nikon lenses with such accuracy; things may look different when i will start to check Tokinas, Tamrons and Soligors.

It is also a fact that Konica AR zooms had wildly varying perfomances whenever i was looking at several samples (not so with Canon FD, Minolta MC/MD/AF and Nikon Ai/AiS/AF zooms!). Specifically that was true for the Hexanon AR zooms 3.5/35-70mm, 2.8/35-100mm, the 4/70-150mm, 3.5/80-200mm and 4/80-200mm UC. Since Konica primes do have equally varying flange distances, maybe that's the origin of the varying zoom performances as well ?!?

So - i try do exclude some obvious mistakes made by other testers, but obviously i can' compete with Roger Cicala Wink. Still, i'm very happy to have feedback and ideas for improving. Reading things like "everything you do is bullshit" (and i do get these kind of emails occasionaly), however, makes me quite sad, to be honest.

Stephan


PostPosted: Mon Apr 10, 2017 7:21 pm    Post subject: Reply with quote
Although I have no intention to buy a 28mm lens (now owning the 24mm thanks to your resources), I really appreciate your effort and integrity in these tests. It's nice to read/view the results - and particularly a godsend for us collectors too. Cheers! Like 1 small


PostPosted: Mon Apr 10, 2017 8:45 pm    Post subject: Reply with quote
Well I tried it, and I now remember why I use the Vivitar S1 28 / 1.9. It's a better lens.

My MC W Rokkor - SG 28 / 3.5 didn't impress me at all today, of course it could be faulty despite it's nearly mint appearance? but if it isn't - then it's the softest 28 I've got. Wide open nothing is sharp, as it closes down 'some' sharpness appears. It's a shame, I really like all my other Rokkors.


PostPosted: Tue Apr 11, 2017 12:44 am    Post subject: Reply with quote
Why not include the Celtics?


PostPosted: Tue Apr 11, 2017 11:48 am    Post subject: Reply with quote
stevemark wrote:
Reading things like "everything you do is bullshit" (and i do get these kind of emails occasionaly), however, makes me quite sad, to be honest.


Stephan,

be assured that there are people like me who really appreciate your work. Having done some lens comparisons myself I know how much work that is. Thank you for your efforts and please continue to publish your findings.

Cheers,


PostPosted: Tue Apr 11, 2017 12:32 pm    Post subject: Reply with quote
tb_a wrote:
stevemark wrote:
Reading things like "everything you do is bullshit" (and i do get these kind of emails occasionaly), however, makes me quite sad, to be honest.


Stephan,

be assured that there are people like me who really appreciate your work. Having done some lens comparisons myself I know how much work that is. Thank you for your efforts and please continue to publish your findings.

Cheers,


I agree 100% Like 1 small


PostPosted: Tue Apr 11, 2017 12:35 pm    Post subject: Reply with quote
tb_a wrote:
stevemark wrote:
Reading things like "everything you do is bullshit" (and i do get these kind of emails occasionaly), however, makes me quite sad, to be honest.


Stephan,

be assured that there are people like me who really appreciate your work. Having done some lens comparisons myself I know how much work that is. Thank you for your efforts and please continue to publish your findings.

Cheers,

+1

Like 1


PostPosted: Tue Apr 11, 2017 12:49 pm    Post subject: Reply with quote
Gardener wrote:
Why not include the Celtics?


Two reasons:

1) in the 28mm range, all Celtics have the same optical formula as the corresponding Rokkors
2) the Celtics are virtually non-existent here in Switzerland, and bying those cheap lenses in the US is not worth the pain

There are only two very early Celtics which differ in their optical construction from their Rokkor counterparts:
* a heavy [5/4] 2.8/135mm (610g) from 1974
* a [6/5] 4/200mm (595g) also from 1974

I do own the Celtic 2.8/135 [5/4], and frankly it doesn't look at all like a Minolta lens (engraving, size, focusing, ...).

Stephan


PostPosted: Tue Apr 11, 2017 2:29 pm    Post subject: Reply with quote
stevemark wrote:
Reading things like "everything you do is bullshit" (and i do get these kind of emails occasionaly), however, makes me quite sad, to be honest.
Stephan

This is most disgraceful.


PostPosted: Tue Apr 11, 2017 3:44 pm    Post subject: Reply with quote
tb_a wrote:
stevemark wrote:
Reading things like "everything you do is bullshit" (and i do get these kind of emails occasionaly), however, makes me quite sad, to be honest.


Stephan,

be assured that there are people like me who really appreciate your work. Having done some lens comparisons myself I know how much work that is. Thank you for your efforts and please continue to publish your findings.

Cheers,


a bit OT ...
Well, I for one am a big Minolta vintage glass fan and artaphot is my reference site. Every time I see a Minolta offered on sale then the fist thing I do is "fly" to the site and check the comparisons ! after that I may look at the other "classical" sites like here and allphotolenses ... Wink


PostPosted: Tue Apr 11, 2017 5:27 pm    Post subject: Reply with quote
tb_a wrote:
stevemark wrote:
Reading things like "everything you do is bullshit" (and i do get these kind of emails occasionaly), however, makes me quite sad, to be honest.


Stephan,

be assured that there are people like me who really appreciate your work. Having done some lens comparisons myself I know how much work that is. Thank you for your efforts and please continue to publish your findings.

Cheers,


+1 Like 1 Happy Dog


PostPosted: Tue Apr 11, 2017 7:15 pm    Post subject: Reply with quote
So Stephan , my 28 2.5 is sharp in the corner at f8 and at f5.6 it is weaker in the extreme corners . It was windy so the leaves cannot be sharp.



f8


f5.6




f8


f5.6


PostPosted: Wed Apr 12, 2017 8:47 pm    Post subject: Reply with quote
@ memeth: Thank you for this additional information!

To me, your f5.6 and f8 crops do not look that different from my f5.6 and f11 crops (my f2.5 crop looks bad, but sadly you didn't show your lens at f2.5!).

The remaining (small) differences might be explainable if you were focusing on the corners whil i was focusing near the center of the image.

At the moment, i have access to only one of my three MC 2.5/28mm (MC-I, MC-II and MC-X), so i can't post crops from all of them yet. Probably on Monday, though Wink. Tomorrow morning i can, however, post a 100% corner crop of an MC-X image focused to the corners.

Stephan


PostPosted: Mon Apr 17, 2017 6:13 am    Post subject: Reply with quote
Lloydy wrote:
Well I tried it, and I now remember why I use the Vivitar S1 28 / 1.9. It's a better lens.

My MC W Rokkor - SG 28 / 3.5 didn't impress me at all today, of course it could be faulty despite it's nearly mint appearance? but if it isn't - then it's the softest 28 I've got. Wide open nothing is sharp, as it closes down 'some' sharpness appears. It's a shame, I really like all my other Rokkors.


I have a mint copy also. All versions of my Minolta 28mm 2.8 lenses are sharper then my SG 28mm f3.5.
That's not the only problem. When I tested the SG 28 3.5 at f3.5 near MFD, the resolution was much lower on this lens, then any of my Minolta 28mm 2.8 lenses. The 28mm f2.8's had much higher resolution at f2.8.


PostPosted: Mon Apr 17, 2017 8:45 am    Post subject: Reply with quote
Thank you Walter, it is as I suspected - the lens isn't the best of Minolta's offerings. Sad
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