[gaweidert]

I have a Kiron-made Viv 28/2.5 that is probably similar to yours. Mine is serial number 22440767 (two years newer than yours) with rubber focus grip and 67mm filter diameter. I am not sure, but yours might be the chrome snout M14 version in Robin Palmar's Great Vivitar 28mm Bestiary; mine is M13 directly above the lens in the link below.

Great Vivitar 28mm Bestiary: Details

Although mine is a clean copy and in good working order, I have never actually shot with it except for a couple of test exposures. I suppose I should see if it has softness at distance similar to yours.


Steve

Looking at those photo mine is the M15.

[stevebrot]

Looking at those photo mine is the M15.

Ohhh...the pre-set aperture version. Cool!


Steve

[Kerrowdown]

Kerrowdown, #3 Shot above is superb. A really well executed image.

Thank you... killing time with a coffee.

[gaweidert]

Thank you... killing time with a coffee.

No, you captured a moment of time while having a coffee.

[Kerrowdown]

No, you captured a moment of time while having a coffee.

Aye your right enough...

[AgentL]

So does consensus hold that the M 28mm 2.8 is on the lower end of performance? I found one for $50 from a different forum, seems a little high but of course the 'Bay tends to run higher, because all film equipment there is inflated these days.

[MSL]

So does consensus hold that the M 28mm 2.8 is on the lower end of performance? I found one for $50 from a different forum, seems a little high but of course the 'Bay tends to run higher, because all film equipment there is inflated these days.

Years ago I asked a question about the A28/2.8 vs F28/2.8. These two lenses, along with the second version of the M28/2.8 all share the same optical formula. However, the F28/2.8 scores way higher in the member lens review (Lens Reviews A28 vs F28 - PentaxForums.com). I still don't have a clear view of why there is such a discrepancy, unless there are more bad or mediocre copies of the M and A versions. My sense is that it is a good lens, but at least for my A28 it loses sharpness at infinity. So if you were to use it for street photography it might be fine, but if you were using it for landscapes (as I was at one point) it might disappoint (which is why I think I have been disappointed by it, when I went back to think about how I had been using the lens).

[richard0170]

Years ago I asked a question about the A28/2.8 vs F28/2.8. These two lenses, along with the second version of the M28/2.8 all share the same optical formula. However, the F28/2.8 scores way higher in the member lens review (Lens Reviews A28 vs F28 - PentaxForums.com). I still don't have a clear view of why there is such a discrepancy, unless there are more bad or mediocre copies of the M and A versions. My sense is that it is a good lens, but at least for my A28 it loses sharpness at infinity. So if you were to use it for street photography it might be fine, but if you were using it for landscapes (as I was at one point) it might disappoint (which is why I think I have been disappointed by it, when I went back to think about how I had been using the lens).

These lenses do share the same optical formula, but do they share the same optical glass? Or is the construction technique and quality the same? Are the coatings having an effect? I do not know. However, I do know that in real world usage my A copy was always disappointing on my K3 at any distance or aperture, but not on the Kx I owned for a while, and the F copy I have is not. I do not even have to pixel peep to see the difference in quality.
I wonder whether the noticeable lower performance on the K3 is something to do with the pixel pitch, or reflections on the pixels themselves. I ponder this as Kerrowdown seems happy with his copy, and if you have seen any of his posted pictures they are of high technical quality, and I believe he shoots on a K1, which of course has a higher resolution, but lower pixel pitch.
One of the reasons that I bought a K3 back in 2015 was that I had a few legacy Pentax lenses (A 28mm, A50mm f1.7 and M 35mm f2.8) and was looking forward to using them on a digital format, particularly liking the 28mm and 50mm FOV on the APSC format. The disappointing performance of the A 28mm and K3 combination has been the major cause of my LAS ever since, in the quest to find the "perfect" 28-30mm for my needs!

[Jonathan Mac]

So does consensus hold that the M 28mm 2.8 is on the lower end of performance? I found one for $50 from a different forum, seems a little high but of course the 'Bay tends to run higher, because all film equipment there is inflated these days.

Correct. The M 28/2.8 is the most common Pentax 28mm lens and it's performance is mediocre.

Years ago I asked a question about the A28/2.8 vs F28/2.8. These two lenses, along with the second version of the M28/2.8 all share the same optical formula. However, the F28/2.8 scores way higher in the member lens review (Lens Reviews A28 vs F28 - PentaxForums.com). I still don't have a clear view of why there is such a discrepancy, unless there are more bad or mediocre copies of the M and A versions. My sense is that it is a good lens, but at least for my A28 it loses sharpness at infinity. So if you were to use it for street photography it might be fine, but if you were using it for landscapes (as I was at one point) it might disappoint (which is why I think I have been disappointed by it, when I went back to think about how I had been using the lens).

There are two versions of the M 28/2.8, with the second one allegedly performing better as it had the same optics as the later A version. I sought one out and can tell you, at least the copies I have or had, the v2 M is still worse than the A version. It's perhaps a little better than the more common v1, but it's not in the same league as the A. I haven't tried the F or FA versions.

[RICHARD L.]

However, the F28/2.8 scores way higher in the member lens review (Lens Reviews A28 vs F28 - PentaxForums.com). I still don't have a clear view of why there is such a discrepancy

People's opinion of a particular lens compared to another almost similar lens can vary a lot, since this is not a "scientific" evaluation but rather an "anecdotal" perception of the relative performances of the reviewed items. Some people will find manual-focusing on an A-series a big liability, others will find the F-series lenses plasticky build or loud autofocus objectionable. You cannot trust the personal evaluation of people of the real imaging performance of two similar lenses that, if put side by side on a serious bench-test, would produce identical results. I recently posted a short review of the F 70-210 mm f/4-5.6 lens, liked the resulting photos it produced a lot and gave it a "10". Another reviewer totally hated it (poor performance, terrible focusing accuracy, creaky plastic construction, etc) and rated it a "2". So where does the truth reside ?


Regards

[Jonathan Mac]

People's opinion of a particular lens compared to another almost similar lens can vary a lot, since this is not a "scientific" evaluation but rather an "anecdotal" perception of the relative performances of the reviewed items. Some people will find manual-focusing on an A-series a big liability, others will find the F-series lenses plasticky build or loud autofocus objectionable. You cannot trust the personal evaluation of people of the real imaging performance of two similar lenses that, if put side by side on a serious bench-test, would produce identical results. I recently posted a short review of the F 70-210 mm f/4-5.6 lens, liked the resulting photos it produced a lot and gave it a "10". Another reviewer totally hated it (poor performance, terrible focusing accuracy, creaky plastic construction, etc) and rated it a "2". So where does the truth reside ?


Regards

Well, given that there is very, very little in the way of real scientific investigation of lenses, anecdotal evidence is all there is. It's not fair to say that one person's opinion is fully valid and can be applied to all copies of all lenses in question, but the combined anecdotal evidence of many people is a reasonable indicator of overall quality. If one lens with 100 reviews scores 9/10 and another with 100 reviews scores 7/10 I can pretty much guarantee that the first one will be better, though each copy can vary.

Some people give lenses 10/10 and say what a great lens it is and then post really terrible photos to back up their claims. I see it in the reviews section all the time. But that's as likely to happen for one lens as it is for any other so the overall score, given enough reviews, is indicative of quality.

[RICHARD L.]

Proof that the evaluation simply reflects the degree of satisfaction a user gets from using a particular lens, even if he takes only "shitty" pictures. Evaluating the quality of pictures taken by somebody else is not the point here, we want to know what results can be obtained by lenses of similar optical construction. Some people will be too generous while others will be more stingy about the final notes they give. As I said, the truth lies somewhere in-between what people say.

[MSL]

These lenses do share the same optical formula, but do they share the same optical glass? Or is the construction technique and quality the same? Are the coatings having an effect? I do not know. However, I do know that in real world usage my A copy was always disappointing on my K3 at any distance or aperture, but not on the Kx I owned for a while, and the F copy I have is not. I do not even have to pixel peep to see the difference in quality.

You ask a lot of good questions and ones we likely can't answer. All I know is that I was disappointed with my A28/2.8 and spent some time wondering whether I should buy a F28 version instead.

People's opinion of a particular lens compared to another almost similar lens can vary a lot, since this is not a "scientific" evaluation but rather an "anecdotal" perception of the relative performances of the reviewed items. Some people will find manual-focusing on an A-series a big liability, others will find the F-series lenses plasticky build or loud autofocus objectionable. You cannot trust the personal evaluation of people of the real imaging performance of two similar lenses that, if put side by side on a serious bench-test, would produce identical results. I recently posted a short review of the F 70-210 mm f/4-5.6 lens, liked the resulting photos it produced a lot and gave it a "10". Another reviewer totally hated it (poor performance, terrible focusing accuracy, creaky plastic construction, etc) and rated it a "2". So where does the truth reside ?

I take a lot more stock in anecdotal performance in real world conditions than I do for a single lens tested under ideal lab conditions with a focusing chart and the camera on a tripod. Photography isn't about truth unless you spend all your time pixel peeping. It is about user experiences and subjective views. For all I know, part of the challenge with the A28 (and M versions) is that the focus throw is so short, that nailing focus is hard, while for the F28 version using AF makes a big difference. I also know that the reviews are highly skewed at times. If you want a good laugh or just to be puzzled, look at the difference in ratings between DA and HD versions of some of the limited lenses. You would largely expect the HD versions to be rated higher, but that often isn't the case and it isn't because you lose a characteristic of the SMC coatings like the starbursts you can get from the DA 15.

[RICHARD L.]

I also know that the reviews are highly skewed at times. If you want a good laugh or just to be puzzled, look at the difference in ratings between DA and HD versions of some of the limited lenses.

Totally true, my friend, totally true !


Regards

[pres589]

Correct. The M 28/2.8 is the most common Pentax 28mm lens and it's performance is mediocre.



There are two versions of the M 28/2.8, with the second one allegedly performing better as it had the same optics as the later A version. I sought one out and can tell you, at least the copies I have or had, the v2 M is still worse than the A version. It's perhaps a little better than the more common v1, but it's not in the same league as the A. I haven't tried the F or FA versions.

Mediocre is a strong word, but the mk1 M 28 f2.8 does seem to be the weakest performing of the glass mentioned in this thread. Here's a good shared comparison test;

5 Lens Comparison @ 28mm using Evening Architecture Composition - PentaxForums.com

That whole thread is interesting when discussing 28mm optics.