K-series vs M-series image quality-wise?

Piotrek K · 10-26-2016, 04:50 AM

There are some basic, lenses in both series which have the same FL and sometimes also the max aperture (like 20/4, 28/3.5, 35/2, 135/3.5, 200/4, some fifties). I'm wondering if the K-series ones are really better in IQ compared to the M-versions? Looking at the PF user reviews database the answer is (should be) yes. But I also know K-series has some cult following so I'm not sure if one will see differences in normal use.

If someone has personal experience and could share it here - I would be gratefull.

P.S. I usually use best of the budget/bargain lenses (like A50/1.7, A 35-70, M135/3.5, some Adaptall's, SMC-Tak 28/3.5, Sigma 24 Superwide...), not high-end ones, so I rather do not ask about *-lenses, K200/2.5 or K135/2.5.

bdery · 10-26-2016, 04:58 AM - **1 Like**

The M lenses are generally smaller, lighter. Optically they often are small evolutions of the K designs, so differences in optical performances should be marginal. If anything they ought to be better, by a hair, if they are truly the same specs (focal length and aperture).

Wild Mark · 10-26-2016, 05:01 AM

The K28/3.5 is definitely better than the M counterpart(s).

I am yet to test the 20mm focal length,side by side, but again I feel the K20/4 is better (but double the size).

I cannot fault the K35/2 and strongly suspect it is far superior to the M series. It is very nice.

The M100/2.8 is very nice indeed and is possibly equal to the K105/2.8. So there are some exceptions.

**UncleVanya** · 10-26-2016, 05:59 AM

My dad worked for Pentax at a time when K was transitioning to M. He claims with conviction that many of the K lenses he was given at first were not as good as the M lenses they were replaced with. This could be sample variation or just basic expectation bias (new lenses = better) or just false memory or perhaps he is correct.

pathdoc · 10-26-2016, 06:07 AM

Originally posted by Wild Mark

The K28/3.5 is definitely better than the M counterpart(s).

Did this, or did this not, essentially keep the optics from the SMC Takumar virtually unchanged?

**baro-nite** · 10-26-2016, 06:15 AM

Originally posted by pathdoc

Did this, or did this not, essentially keep the optics from the SMC Takumar virtually unchanged?

The listing in the lens reviews shows two completely different formulae for the Takumar, the second of which is similar to but definitely not identical to the K version.

I have both the K and M versions. The K deserves its reputation as a classic IMO. I haven't used the M much, just a bit of testing; it seems very good also.

Piotrek K · 10-26-2016, 07:18 AM

Thanks for the replies so far! Any experience regarding telephoto lenses?

**gofour3** · 10-26-2016, 08:35 AM

If you check lens resolution tests from back in the film days, the K Series lenses came out ahead of the M Series most of the time for equivalent focal lengths/maximum aperture.

However there are many M Series lenses that do not match up directly with the K Series, as the maximum apertures/focal lengths are not the same. So can you really compare the K55/1.8 with the M50/1.7 or the K35/3.5 with the M35/2.8 or the K105/2.8 with the M100/2.8?

I find the handling of M Series lenses are not as good as the K Series, due to the smaller size. Also the M Series "skipped" over the harder to shrink K Series lenses, like the 15/3.5, 28/3.5 Shift & 50/1.2.

The M Series in general was more of a budget mini series of lenses, between the more pro K or A series lenses.

Phil.

npc · 10-26-2016, 09:49 AM

Originally posted by pathdoc

Did this, or did this not, essentially keep the optics from the SMC Takumar virtually unchanged?

I think they are all different optics. IQ wise on FF the K is noticably better than the M (mostly the corners) and M is still little better than the SMC Tak.
Visually, M looks to have a smaller front element, elements on the K and SMC tak kind of look the same sizes (maybe rear element of the Tak is a hair smaller) but the K is about 5mm taller than the Tak (just comparing front to rear element distance, not the body shells).

Wild Mark · 10-26-2016, 01:38 PM

Originally posted by pathdoc

Did this, or did this not, essentially keep the optics from the SMC Takumar virtually unchanged?

My understanding is they are different. How much I do not know. Testing the M28 against the K28 shows performance differences. M28 does not produce the sharpness, microcontrast or colours the K28 does.

surfar · 10-26-2016, 02:06 PM

Originally posted by Piotrek K

P.S. I usually use best of the budget/bargain lenses (like A50/1.7, A 35-70, M135/3.5, some Adaptall's, SMC-Tak 28/3.5, Sigma 24 Superwide...),

Me too, but my 35-70 is an Fseries....I own all the others you listed.

m42man · 10-27-2016, 12:05 AM - **2 Likes**

I don't think you can generalise. Some M lenses are optically the same (in terms of elements and groups), so you'd expect similar performance (the M's are more modern, so may have slight improvements, but against that they're smaller and slightly more "plasticky" - though still beautifully made).

Some M lenses either have no K counterpart, or have a completely different optical formula. An example of the latter would be the 135/3.5, where the K has 4 elements in 4 groups (like preceding Takumars - the later ones, that is), the M has 5 elements in 5 groups. The reason would seem to be that the M was made much smaller - though IQ may possibly have suffered slightly in the process.

Piotrek K · 10-27-2016, 02:50 AM

Thank you! All the replies are valuable for me (btw. I know the question itself is quite broad and not easy to answer).

**monochrome** · 10-27-2016, 04:34 AM - **1 Like**

Aside from the optical differences, the M series comparable lenses often have a cooler rendering than the K's attributed to evolution of the SMC coating formula over time. In my personal examples this is especially evident on the 50/1.4 and 100/2.8 - 105/2.8.

pinholecam · 10-27-2016, 07:22 AM - **2 Likes**

The M20/4 is so small and hence easily added to the bag when going out ('just in case') - so is that considered 'better'?

I use it a lot and consider it a gem.

10-26-2016, 04:50 AM	#1
Piotrek K Pentaxian Join Date: Dec 2012 Photos: Gallery Posts: 1,384	K-series vs M-series image quality-wise? There are some basic, lenses in both series which have the same FL and sometimes also the max aperture (like 20/4, 28/3.5, 35/2, 135/3.5, 200/4, some fifties). I'm wondering if the K-series ones are really better in IQ compared to the M-versions? Looking at the PF user reviews database the answer is (should be) yes. But I also know K-series has some cult following so I'm not sure if one will see differences in normal use. If someone has personal experience and could share it here - I would be gratefull. P.S. I usually use best of the budget/bargain lenses (like A50/1.7, A 35-70, M135/3.5, some Adaptall's, SMC-Tak 28/3.5, Sigma 24 Superwide...), not high-end ones, so I rather do not ask about *-lenses, K200/2.5 or K135/2.5.

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10-26-2016, 04:58 AM - 1 Like	#2
bdery Pentaxian Join Date: Mar 2008 Location: Quebec city, Canada Photos: Gallery Posts: 9,362	The M lenses are generally smaller, lighter. Optically they often are small evolutions of the K designs, so differences in optical performances should be marginal. If anything they ought to be better, by a hair, if they are truly the same specs (focal length and aperture).

10-26-2016, 05:01 AM	#3
Wild Mark Veteran Member Join Date: Jun 2013 Location: Newcastle Photos: Gallery \| Albums Posts: 1,954	The K28/3.5 is definitely better than the M counterpart(s). I am yet to test the 20mm focal length,side by side, but again I feel the K20/4 is better (but double the size). I cannot fault the K35/2 and strongly suspect it is far superior to the M series. It is very nice. The M100/2.8 is very nice indeed and is possibly equal to the K105/2.8. So there are some exceptions.

10-26-2016, 05:59 AM	#4
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,452	My dad worked for Pentax at a time when K was transitioning to M. He claims with conviction that many of the K lenses he was given at first were not as good as the M lenses they were replaced with. This could be sample variation or just basic expectation bias (new lenses = better) or just false memory or perhaps he is correct.

10-26-2016, 06:07 AM	#5
pathdoc Pentaxian Join Date: Mar 2015 Photos: Gallery \| Albums Posts: 6,381	Originally posted by Wild Mark The K28/3.5 is definitely better than the M counterpart(s). Did this, or did this not, essentially keep the optics from the SMC Takumar virtually unchanged?

10-26-2016, 06:15 AM	#6
baro-nite Loyal Site Supporter Join Date: Aug 2011 Location: North Carolina, USA Photos: Gallery \| Albums Posts: 5,295	Originally posted by pathdoc Did this, or did this not, essentially keep the optics from the SMC Takumar virtually unchanged? The listing in the lens reviews shows two completely different formulae for the Takumar, the second of which is similar to but definitely not identical to the K version. I have both the K and M versions. The K deserves its reputation as a classic IMO. I haven't used the M much, just a bit of testing; it seems very good also.

10-26-2016, 07:18 AM	#7
Piotrek K Pentaxian Join Date: Dec 2012 Photos: Gallery Posts: 1,384 Original Poster	Thanks for the replies so far! Any experience regarding telephoto lenses?

10-26-2016, 08:35 AM	#8
gofour3 Site Supporter Join Date: Oct 2008 Location: Vancouver, Canada Posts: 8,092	If you check lens resolution tests from back in the film days, the K Series lenses came out ahead of the M Series most of the time for equivalent focal lengths/maximum aperture. However there are many M Series lenses that do not match up directly with the K Series, as the maximum apertures/focal lengths are not the same. So can you really compare the K55/1.8 with the M50/1.7 or the K35/3.5 with the M35/2.8 or the K105/2.8 with the M100/2.8? I find the handling of M Series lenses are not as good as the K Series, due to the smaller size. Also the M Series "skipped" over the harder to shrink K Series lenses, like the 15/3.5, 28/3.5 Shift & 50/1.2. The M Series in general was more of a budget mini series of lenses, between the more pro K or A series lenses. Phil.

10-26-2016, 09:49 AM	#9
npc Veteran Member Join Date: Apr 2013 Posts: 313	Originally posted by pathdoc Did this, or did this not, essentially keep the optics from the SMC Takumar virtually unchanged? I think they are all different optics. IQ wise on FF the K is noticably better than the M (mostly the corners) and M is still little better than the SMC Tak. Visually, M looks to have a smaller front element, elements on the K and SMC tak kind of look the same sizes (maybe rear element of the Tak is a hair smaller) but the K is about 5mm taller than the Tak (just comparing front to rear element distance, not the body shells).

10-26-2016, 01:38 PM	#10
Wild Mark Veteran Member Join Date: Jun 2013 Location: Newcastle Photos: Gallery \| Albums Posts: 1,954	Originally posted by pathdoc Did this, or did this not, essentially keep the optics from the SMC Takumar virtually unchanged? My understanding is they are different. How much I do not know. Testing the M28 against the K28 shows performance differences. M28 does not produce the sharpness, microcontrast or colours the K28 does.

10-26-2016, 02:06 PM	#11
surfar Pentaxian Join Date: Jan 2015 Location: mid nth coast,nsw Photos: Gallery Posts: 6,142	Originally posted by Piotrek K P.S. I usually use best of the budget/bargain lenses (like A50/1.7, A 35-70, M135/3.5, some Adaptall's, SMC-Tak 28/3.5, Sigma 24 Superwide...), Me too, but my 35-70 is an Fseries....I own all the others you listed.

10-27-2016, 12:05 AM - 2 Likes	#12
m42man Veteran Member Join Date: Jan 2010 Location: Southern England Posts: 624	I don't think you can generalise. Some M lenses are optically the same (in terms of elements and groups), so you'd expect similar performance (the M's are more modern, so may have slight improvements, but against that they're smaller and slightly more "plasticky" - though still beautifully made). Some M lenses either have no K counterpart, or have a completely different optical formula. An example of the latter would be the 135/3.5, where the K has 4 elements in 4 groups (like preceding Takumars - the later ones, that is), the M has 5 elements in 5 groups. The reason would seem to be that the M was made much smaller - though IQ may possibly have suffered slightly in the process.

10-27-2016, 02:50 AM	#13
Piotrek K Pentaxian Join Date: Dec 2012 Photos: Gallery Posts: 1,384 Original Poster	Thank you! All the replies are valuable for me (btw. I know the question itself is quite broad and not easy to answer).

10-27-2016, 04:34 AM - 1 Like	#14
monochrome Loyal Site Supporter Join Date: Mar 2008 Location: Working From Home Photos: Gallery \| Albums Posts: 26,276	Aside from the optical differences, the M series comparable lenses often have a cooler rendering than the K's attributed to evolution of the SMC coating formula over time. In my personal examples this is especially evident on the 50/1.4 and 100/2.8 - 105/2.8.

10-27-2016, 07:22 AM - 2 Likes	#15
pinholecam Pentaxian Join Date: Oct 2009 Location: North Photos: Gallery Posts: 4,709	The M20/4 is so small and hence easily added to the bag when going out ('just in case') - so is that considered 'better'? I use it a lot and consider it a gem.