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04-17-2013, 11:31 AM   #31
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QuoteOriginally posted by simbon4o Quote
Those 3.5 28mm pentaxes are so soft in corners... why everybody says they are sharp. Yes colors are great, aberations are well controlled to almost none, but in corners they are soft even at F8.0, I have tested two copies since now and both are soft in corners, only F11 solves that problem. My M 28 2.8 II is sharper at all apertures excluding F16 and F22.
The previous test that I have posted was on K200D, now on K30... 28 3.5 is veery soft in corners compared to 2.8 II version.
I'm with stevebrot and glasbak on this; my K28 3.5 definitely out-resolves my M28 2.8*. Did you test the K28 3.5 as well as the M28 3.5? I also understand from others that the K28 3.5 is a slightly better performer than the M28 3.5, and both were considered better than the M28 2.8 right from the start. I've personally never noticed the K28 3.5 being "so soft" in the corners, but to be fair the kind of photos I take don't need perfect corner to corner sharpness.


*In ways I've posted in a recent review of the K28 3.5. SMC Pentax 28mm F3.5 Reviews - K Prime Lenses - Pentax Lens Reviews & Lens Database

04-17-2013, 11:58 AM   #32
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A little 28mm Pentax history

In the late 90's and early 2000's Yoshihiko Takinami was well known on the Pentax Discuss Mailing List as an authority on the various iterations of Pentax lenses, and for accumulating several copies of each lens and testing them in a controlled fashion against each other, posting the results and declaring his rnarking of the lenses. You can Google to find his postings, some of which still are available today. The following is a summary discussion of the merits of the 28mm K-mount Pentax lenses posted to PDML between 1999 and 2004. The compilation of those postings is available on Stan's Pentax Photography, and is useful still today for information on lenses up to introduction of the FA43/1.9.

I have kept the K28/3.5 and would only replace it with the K28/2 (if I ever had the chance). My M28/3.5 was very close to the K but I've always enjoyed the aesthetics of K lenses better than M or A.

-----------------------------------------------------------------------------------------------------------------------------------------------------------

Yoshihiko Takinami replies:
F28/2.8 is optically identical to M28/2.8 (later model) and A28/2.8, if I remember correctly.
FA28/2.8AL was newly designed when FA lenses were introduced. FA28/2.8AL is a bit soft at wide open, and slightly soft at f/4, while K28/3.5 is very sharp even at wide open.

My personal ranking for Pentax 28m lenses are follows;

K28/3.5, K28/2 >= M28/3.5 >= FA28/2.8AL >>> M28/2.8 (old) >M28/2.8 (later), A28/2.8, F28/2.8

So F28/2.8 is never comparable to FA28/2.8AL in point of optical performance.

Yoshihiko Takinami [again] - I have something to add.
Try Hama rectangular hood (52mm) for this lens. It seems the best hood for K28/3.5 I have ever seen. It also works well with K24/2.8, K28/2, K30/2.8, K35/2, and K35/3.5 in my experiences.
[and in respose to another query . . .]
> I'm out looking for a cheap but good mf (28 or wider) wideangle lens.
> I was thinking maybe one you have a good lens that you are willing to
> give up, or maybe you couldjust give me a tip about what lens I should
> buy.

Go for a used K28/3.5 (SMC PENTAX 28mm f/3.5), a cheap but optically excellent lens, IMO. It is the sharpest 28mm lens that Pentax ever made.
Or go for a used M28/3.5 (smc PENTAX-M 28mm f/3.5), a cheap but good lens, IMHO.

[and in response to yet another query . . .]
First of all, please note that a resolution test is a resolution test. It only shows a part of the optical performance of the lens tested.
As for the K-mount 28mm lenses of Pentax, I have/had experiences with K28/2, K28/3.5, M28/2, M28/2.8, M28/3.5, and FA28/2.8AL. I have resolution test results of K28/3.5, M28/3.5, and FA28/2.8AL among them.
I had been disappointed in the performances of M28/2 and M28/2.8 comparing then to the K lenses and sold them several years ago. So I couldn't test them in the recent resolution test. I actually tested K28/2. But after the test I found it need to be repaired, and deleted the K28/2 result. I will test it [again] . . .

The best among the lenses above, IMHO, is K28/3.5 in point of sharpness, contrast, resolution, and aberrations. The next will be FA28/2.8AL. This is just my opinion.

Last edited by monochrome; 04-17-2013 at 05:17 PM.
04-17-2013, 01:10 PM   #33
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The Pentax 28mm lenses I have tried I would rank like this:

K 28/3.5 ---> M 28/3.5 & M 28/2.8 (II) ---> M 28/2.8

I've never before seen the later model 28/2.8 ranked below the earlier model. Having used both, the earlier version produces the dullest-looking pictures I've ever seen from a DSLR. The second version is no sharper, but has vastly improved colour and contrast. As far as IQ is concerned, there's not much between the middle two shown above. The f/3.5 is significantly sharper wide open, but doesn't have the colour and contrast of the mark II f/2.8.
04-17-2013, 02:09 PM   #34
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QuoteOriginally posted by Jonathan Mac Quote

....the earlier [M28 f2.8] version produces the dullest-looking pictures I've ever seen from a DSLR. The second version is no sharper, but has vastly improved colour and contrast.
I'm so glad you think this! The M28 f2.8 is without doubt my "worst ever" prime Pentax lens purchase, even at $60 for a mint, boxed version. But I was beginning to doubt my sanity/skills when I read some of the reviews on this site and also a couple of the comments on Stan's site, linked above: "like most SMC pentax primes, very good in every way" and "I find my SMC-M 28mm F2.8 excellent in every respect. It's probably the best lens I have ever used in my limited experience". I can sleep happily now.

04-17-2013, 05:19 PM   #35
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QuoteOriginally posted by utak Quote
I'm so glad you think this! The M28 f2.8 is without doubt my "worst ever" prime Pentax lens purchase, even at $60 for a mint, boxed version. But I was beginning to doubt my sanity/skills when I read some of the reviews on this site and also a couple of the comments on Stan's site, linked above: "like most SMC pentax primes, very good in every way" and "I find my SMC-M 28mm F2.8 excellent in every respect. It's probably the best lens I have ever used in my limited experience". I can sleep happily now.
anyone could be (can be - it still exisits) a member of PDML. Also, someone who had owned only the M28/2.8 might make such a post. For instance, my daughter initially liked hers.
04-18-2013, 12:47 AM   #36
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That's funny, because I was already planning to pass off - sorry - on the M28mm to my younger daughter (who is 10) when she is ready. Despite its optical issues the lens is a neat size, has a good classic feel and distinctive look with the yellow K-01, so she'll be pleased....initially.

Last edited by utak; 04-18-2013 at 02:00 AM. Reason: typos
04-18-2013, 02:48 AM   #37
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QuoteOriginally posted by utak Quote
I'm so glad you think this! The M28 f2.8 is without doubt my "worst ever" prime Pentax lens purchase, even at $60 for a mint, boxed version. But I was beginning to doubt my sanity/skills when I read some of the reviews on this site and also a couple of the comments on Stan's site, linked above: "like most SMC pentax primes, very good in every way" and "I find my SMC-M 28mm F2.8 excellent in every respect. It's probably the best lens I have ever used in my limited experience". I can sleep happily now.
I'd suggest that at their price, pick up a couple and compare. Sample variation could explain this. My M 28 3.5 is sharper than the M 28 2.8, but this is only really noticeable under a 25x focus scope with Tmax film shot from a tripod of an Edmund Optics test chart. In normal useage, handheld, the vibration at the point of taking the picture will swamp the difference in performance of these lenses. Both lenses are in good condition, but I actually had the M 28 3.5 professionally serviced, as it was in excellent condition and I figured I'd never sell it.

I've tried 2 copies of the 28 3.5 and 4 copies of the 28 2.8, one of which was the later model.

But, as I say, to get to the 90lpmm level, you need to have a set up which allows you to see 90lpmm. If the lens exceeds the resolution capabilities of the setup, you will be restricted by the set up and not the lens.
04-18-2013, 04:06 AM   #38
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QuoteOriginally posted by whojammyflip Quote
I'd suggest that at their price, pick up a couple and compare. Sample variation could explain this.
Thanks but I'll have to pass, and I just don't have the ability to test like you describe. But given my criticisms above (and I have some spare time) I feel I should be more specific about some experiences with the M28 2.8.

Firstly, I was commissioned to take some photos of different car headlights/designs (they are infact quite fascinating), and I used the M28 for the job, on the streets, from about 3 feet in sunlight. Although the lens was not as sharp as my DA35mm macro, it was easily sharp enough and it produced a slightly quirky/distinctive set of images. So a tick.

Secondly, on a number of occassions I've taken the lens+hood on family walkabouts and snapped group photos at around 20 feet infront of buildings, trees etc, with light and shadows etc etc. The results were dull! But worse, it was hard to pep up the images afterwards because the resolution was simply not good enough to handle a lot of change, and parts of the images quickly became fuzzy. A cross.

Thirdly, we were on a beach witnessing a most magnificant sunset/effect as the sunlight seeped through the clouds. I only had the M28mm and took loads of photos, at infinity, not difficult. But none of them came as good as I'd hoped, and it was hard to crop into the clouds or print beyond A4. The lens just didn't capture enough of what we saw. That's when I went out and purchased the K28mm, and I've never looked back.

Perhaps the M28 2.8 is optimised for test charts and objects at around 3 feet? Really, I could believe that.


Last edited by utak; 04-25-2013 at 10:31 AM. Reason: added 4 words, non-working photo link removed
04-18-2013, 05:11 AM   #39
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Impossible really to say anything about optical quality from a picture which could be taken equally well with a small format....you'd really need to post a large version. Nice shot though.

I seriously doubt Pentax optimised a lens for 3 foot distances. Although the M 28/2.8 may not be Distagon sharp, its no slouch. The M 28/3.5 is in comparison an incredibly sharp lens, sharper than the Tamron 90/2.5 in my experience. To put that in context, Barry Thornton touted the Tamron 90/2.5 as being able to put 35mm into a similar IQ as medium format. Before slating a lens, its worth considering whether you simply have a bad copy.

One of the issues you will experience, too, is quality of light affecting the resolution of a lens on any given day. If the scene you took of family etc where you were disappointed with the lens was a flatly lit day, the photos will inherently demonstrate lower contrast, making the lens appear less than stellar.

Dont get me wrong, I am not defending the M 28/2.8 as being the best lens, as a 50mm Bronica Zenzanon PE cleans the floor with it. But in comparison to the third party alternatives, such as the Kiron 28 f2, I'd suggest the M 28/2.8 is very strong contender.
04-18-2013, 06:43 AM   #40
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Thanks whojammyflip, we can 100% agree that the Pentax K28mm 3.5 and M28 3.5 are great lenses, but forget this thread, I'm off to look at that 50mm Bronica Zenzanon PE.
04-18-2013, 07:49 AM   #41
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Until very recently, maybe the start of this year, Tamron were keeping the web pages alive for the various PE lenses, with MTF diagrams....you might be able to find these still through the archive.org website. I seem to recall the MTF diagrams show the 50mm is sharper than the 40mm. These lenses were very expensive when new (still being made in 2004), yet can be bought very cheaply as they are camera specific, and you only get 15 shots on a roll of film, which takes 30 mins to develop. Not for the faint hearted, but if you only have a couple of 16x12's to hang on a wall, why compromise
04-18-2013, 03:23 PM   #42
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QuoteQuote:
Yoshihiko Takinami replies:
F28/2.8 is optically identical to M28/2.8 (later model) and A28/2.8, if I remember correctly.
FA28/2.8AL was newly designed when FA lenses were introduced. FA28/2.8AL is a bit soft at wide open, and slightly soft at f/4, while K28/3.5 is very sharp even at wide open.

My personal ranking for Pentax 28m lenses are follows;

K28/3.5, K28/2 >= M28/3.5 >= FA28/2.8AL >>> M28/2.8 (old) >M28/2.8 (later), A28/2.8, F28/2.8

So F28/2.8 is never comparable to FA28/2.8AL in point of optical performance.
I think he was wrong to put the F version last. (Last in a beauty contest, absolutely. ) He obviously saw something he didn't like with that formula, condemning the whole series. Maybe it doesn't work on film.
04-18-2013, 03:57 PM   #43
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Hi Guys,

I've been away from this forum for a while, but do remember this thread when it started (I can't believe it is still running). My favourite prime focal length on film was my M40/2.8, on APS-C it is similarly 28mm - I only have the first version of the M28/2.8 (well two copies - one has a developed a 'click' from the focus ring). Ideally I'd prefer an f/2 (even if only for a brighter finder), as there isn't a Ltd. one available, I'm considering looking for a Zeiss ZK 28/2 instead.

John.
04-19-2013, 02:04 AM   #44
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QuoteOriginally posted by Jonathan Mac Quote
The largest common aperture should be f/4. The f/3.5 lenses have one click-stop between wide open and f/5.6, I understand that this is f/4, though I haven't tested it. I could have tested them all at this aperture, but I always like to know how a lens performs wide open. Obviously these kind of shots (landscapes) wouldn't normally be made wide open, but sharpness, colour and contrast are the same regardless of the subject (if not the shooting conditions).

I have been using the Vivitar on film a bit recently (though I haven't processed them yet), and I think on the results here I'll stop doing so. I normally PP my digital shots, but not so much with film, as the scans I've had done so far have been done in my local place and are hugely over-sharpened jpegs, so no RAW unlike the digital.
The largest common aperture should be f/4. The f/3.5 lenses have one click-stop between wide open and f/5.6, I understand that this is f/4, though I haven't tested it. I could have tested them all at this aperture, but I always like to know how a lens performs wide open. Obviously these kind of shots (landscapes) wouldn't normally be made wide open, but sharpness, colour and contrast are the same regardless of the subject (if not the shooting conditions).

From PentaxForums.com: https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/193250-manual-...#ixzz2Qtjgf4bf

According to old catalogues and brochures of Pentax lenses , the click stop between f/3,5 and f/5,6 is 4,8 for the lenses with a max. aperture of 3,5. Also the same applies for the click stop between 4 and 5,6.

Regards

Regards
04-19-2013, 01:51 PM   #45
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M2.8/28 (with K7, Original here: http://www.flickr.com/photos/32108329@N08/8414055101/sizes/o/in/photostream/) I find it comes alive at f/11.

Last edited by jt_cph_dk; 04-19-2013 at 02:07 PM.
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