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10-02-2009, 01:36 PM   #1
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K or M Series - Which has the best image quality

Here’s a question for old timers (like myself) or others who have used both K and M series lenses. In your opinion which series of lenses do you think has better IQ – the K or M series? For the sake of discussion let’s not include the build quality of the lenses and focus only on the images they produce. Consider such factors as sharpness, contrast, colour and bokeh. I realize this will be subjective but I’m curious to hear your opinions. Include some of your images to illustrate your opinions if time allows.

Tom G


Last edited by 8540tomg; 10-02-2009 at 01:36 PM. Reason: typo
10-02-2009, 02:04 PM - 1 Like   #2
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OK, here is what I have used (SMCT means I've used the takumar version which is the same optically)

K24/2.8
K24/3.5
K35/3.5
K50/1.4
K55/1.8
K85/1.8 (SMCT)
K105/2.8 (SMCT)
K135/2.5
K200/4 (SMCT)

M28/2.8
M35/2.8
M40/2.8
M50/1.4
M50/1.7
M85/2
M100/2.8
M135/3.5

In general, I think that the K's have a bit more pleasing rendition, with generally less issues with purple fringing (and K's seem to have some green fringing in certain cases). It's sort a toss up to talk in generalities, so I'll detail each lens individually.

Wide angle: K24/3.5 was my favorite. Blistering sharp even wide open and really great colors, with interesting bokeh if you are close enough to get some. The K24/2.8 was nice too but I like the K24/3.5 output better. M28/2.8 had significant purple fringing on high contrast borders.

Normal: Pretty much a toss up, but K50/1.4 was my favorite, although my one and only copy had fungus and is now trashed . K55/1.8 and M50/1.7 seem a bit sharper when used wide open and are both great performers, with the K55 having the slight favor.

Portrait: M85 is super sharp wide open, but can have horrible purple fringing on high contrast. I love using it, I actually think the PF and super sharpness help aid in MF using it. The K85 is definitely a tad softer wide open, but the bokeh is clearly smoother at large apertures and there is not much color fringing (maybe small amount of green). Smaller apertures they are pretty close. K85 seemed harder to nail the focus consistently.

Short tele: M100/2.8 is great, very sharp wide open and a few optical abberations, but a good one to use. My copy of the SMCT105/2.8 didn't seem as good, although I never had them both at the same time to compare... I could have just been in different moods.

Tele: K135/2.5 is the master of them all. The M is nice in it's compactness, but the bokeh that the 2.5 produces is just wonderful, and the rendering is extremely pleasing at any aperture. I have both the K135/2.5 and the SMCT135/2.5 and I can't let either one go . I have never had a K135/3.5 so I can't comment on it.
10-02-2009, 02:05 PM   #3
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QuoteOriginally posted by 8540tomg Quote
Here’s a question for old timers (like myself) or others who have used both K and M series lenses. In your opinion which series of lenses do you think has better IQ – the K or M series? For the sake of discussion let’s not include the build quality of the lenses and focus only on the images they produce. Consider such factors as sharpness, contrast, colour and bokeh. I realize this will be subjective but I’m curious to hear your opinions. Include some of your images to illustrate your opinions if time allows.

Tom G
Hi Tom:

Well I’m an old timer, but have no M series lenses, just K. So I guess I’ll have to follow the thread and keep quite.

Good idea for the thread, looking forward to the responses.

Phil
10-02-2009, 02:27 PM   #4
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For film this is simple, name me one M lens, which optically outperforms the K lens it replaced.
(I know of maybe 2).

On APS-C this is more difficult, the compact build of the M lenses had the most impact on the image quality at the outer region of the image on film, while the center was quite decent. So maybe the difference between K and M on APS-C is not that large as on film

George

10-02-2009, 02:42 PM   #5
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Arpaagent,

This is exactly the sort of response I had hoped for. Some great information and well considered opinion from one who has used both series. I can’t comment on the K 105/2.8 but I had the M 100/2.8 for many years and concur with your opinions on it. It produced some of my best portraits on film. I’m sad to say I sold it so I can’t really comment on its performance on the digital stage.

I have several K and M series lenses but I only overlap at the 200mm focal length. This is the reason I started this thread. While I like my M 200/4 it is hardly fair to compare it to its much more expensive K series cousin the K 200/2.5. While the M is sharp the K is razor sharp and the extra 2.5 speed makes it much easier to focus. You do get what you pay for in this case. I didn’t have the M 200/4 with me but experience indicates the following K 200/2.5 image would not have been as good with the M 200/4.




jsherman999 coined a new word when speaking of the K 200/2.5 in another post and says it has "sharptitude," - I agree. In fairness the comparison is moot as we are comparing a Ferrari to a Ford. A more valid comparison would be the K 200/4 with the M 200/4. The intent here is not to trash one series or the other but rather to find which lenses in each series perform the best.

Ben Edict/Wheatfield. If you guys come across this thread I would appreciate your thoughts as you fellows seem to have owned/used just about every Pentax lens ever made.



Cheers

Tom G

Last edited by 8540tomg; 10-02-2009 at 08:59 PM. Reason: typo
10-02-2009, 02:48 PM   #6
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QuoteOriginally posted by glasbak Quote
For film this is simple, name me one M lens, which optically outperforms the K lens it replaced.
(I know of maybe 2).

On APS-C this is more difficult, the compact build of the M lenses had the most impact on the image quality at the outer region of the image on film, while the center was quite decent. So maybe the difference between K and M on APS-C is not that large as on film

George
Great point George. I had intended to limit the comparison to performance on APS-C and should have been more clear in that regard. I shoot so little film these days I didn't think of it.

Tom G

Last edited by 8540tomg; 10-02-2009 at 02:54 PM. Reason: typo
10-02-2009, 02:52 PM   #7
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QuoteOriginally posted by gofour3 Quote
Hi Tom:

Well Iím an old timer, but have no M series lenses, just K. So I guess Iíll have to follow the thread and keep quite.

Good idea for the thread, looking forward to the responses.

Phil
I agree Phil. It should be interesting.

Tom G
10-02-2009, 03:31 PM   #8
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QuoteOriginally posted by arpaagent Quote
Short tele: M100/2.8 is great, very sharp wide open and a few optical abberations, but a good one to use. My copy of the SMCT105/2.8 didn't seem as good, although I never had them both at the same time to compare... I could have just been in different moods.
interesting comment, I took a K105mm over the M100 because I had an impression that the M100 focusing collor was inconsistent in feel.

the K105 is a nice lens but a little soft wide open, at least my copy seems that way

10-02-2009, 04:21 PM   #9
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You might have just handled a poorly maintains M100. Can't say I've noticed any issues with mine or my wife's. I know some early opinions (on film) were that the M100/2.8 is not as strong as the K105/2.8, and it's numbers don't look so hot in Yoshihiko Takinami's tests; but the two direct comparisons I've seen on APS-C show the M100/2.8 beating the K105/2.8 by about as a large a margin as I've ever seen one prime beat another.
10-02-2009, 04:25 PM   #10
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QuoteOriginally posted by Marc Sabatella Quote
You might have just handled a poorly maintains M100. Can't say I've noticed any issues with mine or my wife's. I know some early opinions (on film) were that the M100/2.8 is not as strong as the K105/2.8, and it's numbers don't look so hot in Yoshihiko Takinami's tests; but the two direct comparisons I've seen on APS-C show the M100/2.8 beating the K105/2.8 by about as a large a margin as I've ever seen one prime beat another.
makes me want to go back for the M100, I know where it still is.

No, must resist LBA
10-02-2009, 04:31 PM   #11
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QuoteOriginally posted by Marc Sabatella Quote
You might have just handled a poorly maintains M100. Can't say I've noticed any issues with mine or my wife's. I know some early opinions (on film) were that the M100/2.8 is not as strong as the K105/2.8, and it's numbers don't look so hot in Yoshihiko Takinami's tests; but the two direct comparisons I've seen on APS-C show the M100/2.8 beating the K105/2.8 by about as a large a margin as I've ever seen one prime beat another.
Interesting about the M100 and with Lowell's comment...mine also had some issues with the focusing action...the resistance was uneven though parts of the focus throw. This was one of the reasons that I got rid of mine, well and the fact that I wanted an A100/2.8 (although have yet to find one). The fact there are a few examples of poor focusing on the M's may say something about the general better build of the K lenses (maybe lasting longer?), which I don't want to bring into discussion here as per the OP's request...but just thought iId mention my experience with it as well.

PS I've been after a K200/2.5 for a while now, really wanting that lens. It may even be on the top of the list for me. It just seems so sexy.

Cheers
-Jim
10-02-2009, 04:31 PM   #12
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QuoteOriginally posted by Marc Sabatella Quote
You might have just handled a poorly maintains M100. Can't say I've noticed any issues with mine or my wife's. I know some early opinions (on film) were that the M100/2.8 is not as strong as the K105/2.8, and it's numbers don't look so hot in Yoshihiko Takinami's tests; but the two direct comparisons I've seen on APS-C show the M100/2.8 beating the K105/2.8 by about as a large a margin as I've ever seen one prime beat another.
Any chance of a couple of simple comparison shots M 100/2.8 vs K 105/2.8 Marc?
It would be informative. I was of the opinion the K 105/2.8 was a gem.

Tom G

Last edited by 8540tomg; 10-02-2009 at 05:46 PM. Reason: typo
10-02-2009, 04:39 PM   #13
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QuoteOriginally posted by arpaagent Quote
PS I've been after a K200/2.5 for a while now, really wanting that lens. It may even be on the top of the list for me. It just seems so sexy.

Cheers
-Jim
Jim

The K 200/2.5 isn't just hot it's smokin hot. I've said it before in several posts this is my favourite lens by far. I noticed there are a couple on EBAY at the moment if you are interested. (not mine by-the-way)

Tom G

Last edited by 8540tomg; 10-02-2009 at 04:56 PM. Reason: typo
10-02-2009, 04:44 PM - 1 Like   #14
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QuoteOriginally posted by 8540tomg Quote
Ben Edict/Wheatfield. If you come across this thread I would appreciate your thoughts as you guys seem to have owned and used just about every Pentax lens ever made.

Tom, I guess, Wheatfield may have a considerable advantage here... I have only a few K lenses (15/3.5, 28mm shift, 135/2.5, 300/4 and 500/4.5), which all have no real equivalent in the M series. I think this is due to the very different philosophy of these lens series, where Pentax gave priority to the small form factor of the M series.

For those lenses I have, I can hardly make a comparisson, but give my opinion:

15/3.5 - simply superb. Holds up very nicely even on current DSLRs in terms of sharpness and contrast and very pleasing colour rendition, with the only drawback being its poor flare resistance (despite SMC). No equivalent in the M series.

28 shift - very useful and good IQ at longer distances (for which is was made) even at max. shift, when stopped down to f/8 or f/11, but extraordinary poor performance at short distances (studio) up to the point, that I find it unusable. Continued throughout the production run of the M series.

135/2.5 - a very nice and sharp lens - I use it to rarely I confess, it deserves more...

300/4 - in the M series there was the M* 300/4, which is basically the same design as the later A*, just without the A-contacts. As the A* outperforms the K 300 in every single aspect, I would expect the same from the M*. Nevertheless the K300 is a nice performer, albeit a bit slower i use (no IF) and with some very visible CAs in high contrast situations.

500/4.5 - a lens which proved itself a worthy contender over the decades. No equivalent in the M series. Slow, big, but sharp and contrasty. Very prone to CA. CAs can be worsened to the degree of rendering the lens unuseable, when teamed up with the 1.7x AF-adaptor.


Of the M series lenses I used, I find the 50/1.4 and the 35/2 not really remarkable. In both cases the later lenses, like the A and FA 50/1.4 and the FA 35/2 (I haven't got the A 35/2) are sharper wide open. Nevertheless the M 50/1.4 might be a good choice as a portrait lens on a DSLR, just because it isn't overly sharp... The M 35/2 was one of my two favourite lenses in film days, though.

THe M 85/2 is a very nice lens, because it is fairly fast, sharp and contrasty and handles nicely. It was a favourite of mine in film days. I often only had a MX body, the 85/2 and the 35/2 with me, when I travelled light. The 85mm still makes it into my equipment bag, whereas the 35 is retuired.

Oh, thing I should mention: The M 35/2 is probably the one lens in the Pentax lineup, that cause the most troubles with sticky aperture blades. I have yet to see a sample, that did NOT suffer from this at one time in its life...

Oh, I should not forget my final remark: I envy your 200/2.5 ...

Ben
10-02-2009, 05:41 PM   #15
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Ben,

Great insights as usual. Some very good observations to use in conjunction with opinion in the lens review area. I have the M 35/2 and while I like it I don't use it very often. I'm just not fond of this focal length. Granted, it is soft at f2 but sharpens up quite quickly and is the smoothest focusing manual lens I have ever used. For the record, I just took a look at my M 35/2 and the blades seem just fine. Could be the lack of use but I’ll keep an eye on it in any case.

I’m surprised you don't have the K 200/2.5 Ben. Probably not one of your favourite focal lenghts. Some have reported CAs wide open but it remains one of the sharpest 200s Pentax ever produced including the most recent models. It certainly meets my needs.

kbrabble, who has owned both, in writing of the DA * 200/2.8 in the lens review forum says:

“I believe the K (K 200/2.5) is a little better optically, it is slightly sharper wide open, and has better (at least different) bokeh. However the DA* is also excellent in these aspects, and the modern conveniences, closer focusing, and lighter weight more than make up for the slight loss in image quality.”

Nice to know the K 200/2.5 has stood up so well over the years. It would be fun to compare the two but this is a K/M series comparison thread.

PS I envy your K 15/3.5, K 28mm shift, K 135/2.5, A* 300/4, K 500/4.5 - I could go on but what's the point.

Tom G

Last edited by 8540tomg; 10-04-2009 at 04:57 AM. Reason: typo
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