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Archive 2008 · Minolta 28/2.0 impressions

JimBuchanan
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p.1 #1 · p.1 #1 · Minolta 28/2.0 impressions

I have completed the EOS conversion of a late, "plain MD" 28/2.0 lens. I am very impressed so far. My design goal was to find a 28mm for Canon crop camera use to retain the small size profile, without compromising on performance. My benchmark is a perfect Leica 28mm Elmarit, late. It is still king of the hill, but this Minolta, at 1/3 to 1/5 the price is a run away winner, in my opinion.

The subject of my test so far is corner sharpness and contrast at wider apertures, and chromic aberrations. I've already looked at the Oly 28/2.0 and passed on that one as the chromic aberrations were objectionable. I do realize that the adapter issue can skew performance and that could be the case with the Oly. Here is the comparisioin photos that were originally posted in the Oly 28/2.0 thread.
http://farm4.static.flickr.com/3097/2920900456_215820c6a4_o.jpg

The Minolta, on the other hand, is slightly less sharp than the Leica at wide apertures, but the big deal with me is there is very little Chromic aberrations (objects with red on one side and purple on the other). The Minolta f/4 image below is almost identical to the Elmarit f/2/8 image. Not bad. For some reason, the Minolta at infinity setting will hold focus closer than the Elmarit. A bonus for scenics.
http://farm4.static.flickr.com/3221/2929106187_0c2e0b22d9_o.jpg

Oct 10, 2008 at 02:02 PM

rgallie
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p.1 #2 · p.1 #2 · Minolta 28/2.0 impressions

Glad you got a good copy of the lens and the conversion is good.

My copy of the lens shows excellent corner sharpness on a 5D, but with some CA.

The 28/2 was introduced in Jan 1975 and it is hard to find tests or comments about it. It seems to be barely noticed. I wonder if there were very many produced or sold.

Rodney

Oct 10, 2008 at 02:53 PM

JimBuchanan
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p.1 #3 · p.1 #3 · Minolta 28/2.0 impressions

In the alternate lens world, the lenses that adapters exist for, get the exposure. Case in point is the Oly lenses. To use a Minolta lens, one has to take the extra step. We know an Oly 18/3.5 is a great lens, but anyone have experience with the Minolta 17mm? I bought one and let it go before I learned how to convert Minolta lenses.

I really believe the adapter introduces twice the source for error, 2 mating surfaces versus 4, with the adapter in-between. Add to that, variation of lens manufacture, and its a veritable crap shoot, to find that lens solution.

Oct 10, 2008 at 03:06 PM

Ed Sawyer
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p.1 #4 · p.1 #4 · Minolta 28/2.0 impressions

Nice work! I am amazed at how good the Leica is, in comparison to the Oly and Rokkor, which are no slouches or at least shouldn't be. Not to be non-alt but I wonder how the non-L fixed focal length Canon 28s do...

-Ed

Oct 10, 2008 at 07:28 PM

JimBuchanan
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p.1 #5 · p.1 #5 · Minolta 28/2.0 impressions

Here is the 28mm champ and its little brother:
http://farm4.static.flickr.com/3143/2931632529_0f58128acf_o.jpg

Oct 11, 2008 at 05:57 PM

apras
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p.1 #6 · p.1 #6 · Minolta 28/2.0 impressions

wow nice finding. is it easy to convert?

Oct 13, 2008 at 01:07 AM

JimBuchanan
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p.1 #7 · p.1 #7 · Minolta 28/2.0 impressions

To further illustrate my impressions of the Minolta 28/2.0, I have comparison photos (left edge of a XSi frame) of the Elmarit 28/2.8, Oly 28/2.0, and Minolta 28/2.0. I acknowledge this is a quick and dirty comparison with many variables, the least of which is the slightly out-of-focus Oly shot. The main aberration in the Oly 28 photo that is absent in the other 2 is what I call pink fringing above the wood trellis. Secondly, and not very evident in these photos is the red/ blue edges on either side of the umbrella crown. The Oly had more of this than the Minolta. I find that upon stopping down a lens, the “pink fringing” goes away, but the “red/blue” edges do not, as easily. This second aberration is very objectionable to me. Feel free to label these aberrations, as I get confused with what they are called.

Because the Minolta 28/2.0 has so little of the above described aberrations and was almost as sharp as the Elmarit, I stopped tweaking the infinity focus. Being a floating element design and adjusting infinity focus by the thickness of the EOS conversion flange, if I went too far thining the flange, I can’t put the metal back. So, chances are I’m on the money, but maybe after living with it for a while, I could fine tune the sharpness.

As far as sharpness is concerned, I am referring to the concept of a spherical focus plane and having a choice of putting the absolute infinity focus in the center of the frame or putting it more toward the edge and sacrificing the center sharpness a bit. Said another way, the spherical plane of focus is pushed through the sensor plane to where the edges gain sharpness. This would be the result if a few more .001 inch were taken out of the optical path.
http://farm4.static.flickr.com/3072/2943859532_fff2fb21c9_o.jpg

Oct 14, 2008 at 11:36 PM

pdmphoto
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p.1 #8 · p.1 #8 · Minolta 28/2.0 impressions

I think the pink fringing would be about equal on the Minolta and Oly, if the Oly had as good focus (it looks to be CA in the out of focus focus areas, which is common with many lenses wide open). The Oly focus is more than a little off. Also, the umbrella crown figure is much smaller in the Minolta 28/2 shot

It's smaller and more out of focus, so it's harder to see any edge red/blue areas - where there is no clear edge. To be honest I see a good amount as is. Why such a large discrepancy in the sizes?

I'm a huge fan of Minolta lenses, shooting with Minolta Maxxum film for almost ten years. The Maxxum 28/2 was my favorite landscape lens, providing excellent results. But I've also had a few copies of the Oly 28/2, and I think you have a poor lens ior adapter, and are doing a poor job of representing it.

Oct 15, 2008 at 12:15 AM

olyacme
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p.1 #9 · p.1 #9 · Minolta 28/2.0 impressions

JimBuchanan wrote:
The main aberration in the Oly 28 photo that is absent in the other 2 is what I call pink fringing above the wood trellis. Secondly, and not very evident in these photos is the red/ blue edges on either side of the umbrella crown. The Oly had more of this than the Minolta. I find that upon stopping down a lens, the “pink fringing” goes away, but the “red/blue” edges do not, as easily. This second aberration is very objectionable to me. Feel free to label these aberrations, as I get confused with what they are called.

FWIW your "pink fringe" looks a lot like Coma, and the red/blue fringes are without a doubt lateral CA. Missed focus (or field curvature) and spherical aberration may be making contributions as well.

I'd like to see some examples of these lenses live view (or iteratively) focused from a 135 format camera. The OMZ 28/2 was not cheap when new, and some references believe it to be very sharp, yet I've never seen a good performing example myself. Wide open mine is even already falling apart at the corners on fourthirds.

Oct 15, 2008 at 01:01 AM

JimBuchanan
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p.1 #10 · p.1 #10 · Minolta 28/2.0 impressions

pdmphoto wrote:
The Oly focus is more than a little off. Also, the umbrella crown figure is much smaller in the Minolta 28/2 shot

It's smaller and more out of focus, so it's harder to see any edge red/blue areas - where there is no clear edge. To be honest I see a good amount as is. Why such a large discrepancy in the sizes?

But I've also had a few copies of the Oly 28/2, and I think you have a poor lens ior adapter, and are doing a poor job of representing it.

The difference in size is the Minolta shot was taken at a later date, but at the same time of day to get the sun position the same. That was my mistake for not duplicating the scale.

Fair statement about the Oly 28. This whole thread was an attempt to describe what I saw as aberrations in the Oly and hardly any in the Minolta. Not included above, but I also used a Oly 28/3.5 in the trellis/umbrella shots with the same adapter as used on the Oly28/2.0. There was no pink fringing or red/blue edges at all. Additionally, the exposure difference between f/2 and f/2.8 was less than one stop on the Oly28/2.0.

I realize certain weaknesses in my method and the possibility of adapter issues. Like I said "quick and dirty comparison with many variables" I sold the Oly because of these aberrations and can't go back to retest.

Going forward, I've found a very acceptable 28mm that is almost the equal of the Leica 28, at about $300 bucks, that will be part of a XSi crop camera system as the normal focal length.

Thanks, for your comments.

Oct 15, 2008 at 09:09 AM

wayne seltzer
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p.1 #11 · p.1 #11 · Minolta 28/2.0 impressions

Jim,

I just took my Minolta MD 28 apart and saw that the aperture ring doesn't directly connect to the aperture post but uses a springed lever attached to the underside of the bayonnet mount to press against the aperture post. So it looks like you some how kept the center part of the mount and added the eos m42 mount around it.
Is this lens easy to convert like the Rokkor 58 which I did myself or is it complicated and thus maybe better to send for conversion?

Aug 09, 2009 at 09:08 PM

JimBuchanan
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p.1 #12 · p.1 #12 · Minolta 28/2.0 impressions

Hi, Wayne.

Like most all Minolta lenses, except the 58s, the aperture linkage is on the inner side of the back, It is a cam arrangement, meaning the equal spacings between f/stops of the aperture ring translate thru the cam to different blade movements. It is because of this, the inherent strength of the original back, and the fact that the EOS bayonet is a larger diameter, that my method is to retain the back and slip a EF bayonet over the Minolta bayonet. Unfortunately, this is a one by one custom modification, using a lathe.

As far as infinity adjustments are concerned, it is very easy to use the adjustment screws to compensate for the .5mm register difference. In the case of the 24/2.8, 28/2.0, the 24VFC, or any other floating element lens, I use the lathe to remove the optical path from the inside of the back assembly, several .001" at a time until proper infinity focus is reached.

Sorry, I don't have any photos to illustrate the process.

Aug 09, 2009 at 11:40 PM

wayne seltzer
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p.1 #13 · p.1 #13 · Minolta 28/2.0 impressions

Ok, thanks for the response.
It sounds pretty involved ...
I just sent you a PM.

Thanks!

Aug 10, 2009 at 12:52 AM

ulrikft
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p.1 #14 · p.1 #14 · Minolta 28/2.0 impressions

How would this compare?

http://tinyurl.com/leica28-28

I'm thinking about something like that, as my first leitax-nikon leica experiment. But I got a very nice 24 2.0 that i think is quite nice too. Don't know if the leica will be a large improvement.

Aug 10, 2009 at 02:10 AM

m-a-x
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p.1 #15 · p.1 #15 · Minolta 28/2.0 impressions

Congratulatuions!
The new mount of your Minolta looks clean and clear like out of a factory

Aug 10, 2009 at 04:31 AM

thrice
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p.1 #16 · p.1 #16 · Minolta 28/2.0 impressions

Ulrik, the original 28mm elmarit is no slouch, although at 100% the new version is definitely the corner to corner winner. It's a good lens with great colour and the characteristic leica glow

Aug 10, 2009 at 05:02 AM

ulrikft
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p.1 #17 · p.1 #17 · Minolta 28/2.0 impressions

Ah, ok! I see, I guess I'll try to get my hold on a leica to test it against the 24 2.0. The 24 2.0 is a bit hazy wide open, but is great from 2.8. The distortion/field curvature is.. a bit bad though.

Aug 10, 2009 at 05:04 AM

TWoK
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p.1 #18 · p.1 #18 · Minolta 28/2.0 impressions

The 24/2 AIS is very sharp in the center wide open. I loved mine.

Aug 10, 2009 at 05:45 AM

brainiac
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p.1 #19 · p.1 #19 · Minolta 28/2.0 impressions

ulrikft wrote:
How would this compare?

http://tinyurl.com/leica28-28

I'm thinking about something like that, as my first leitax-nikon leica experiment. But I got a very nice 24 2.0 that i think is quite nice too. Don't know if the leica will be a large improvement.

The older Leica 28, without the built-in square hood, is reputed to be a dog. Square built-in hood or don't bother.

Aug 11, 2009 at 04:53 AM

thrice
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p.1 #20 · p.1 #20 · Minolta 28/2.0 impressions

brainiac wrote:
The older Leica 28, without the built-in square hood, is reputed to be a dog. Square built-in hood or don't bother.

Don't bother with the new one either, too much contrast in the oof areas!

Aug 11, 2009 at 05:54 AM

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