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04-29-2013, 12:18 AM   #1
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Pentax vs Sigma

Hi everyone,

yesterday i had some time and since the weather did not allowed something else i decided to make a small comparison between my lenses. Pentax DA40mm, Pentax FA 77, Pentax M 50mm 1.4, Sigma 105 Macro 2.8 (non DG version), Sigma 70-200 2.8 (non DG Version)


Pentax 40mm 2.8



Pentax 40mm 3.5



Pentax 40mm 5.6



Pentax M 50mm 1.4



Pentax M 50mm 2.8



Pentax M 50mm 5.6



Pentax 77mm 1.8



Pentax 77mm 2.8



Pentax 77mm 5.6



Sigma 105 2.8



Sigma 105 3.5



Sigma 105 5.6



Sigma 70-200 @ 200mm 2.8



Sigma 70-200 @ 200mm 3.5



Sigma 70-200 @ 200mm 5.6



So my thoughts for my little comparison...

I recently bought the FA 77mm 1.8 and i must say in the beginning i was not so thrilled with the results. To achieve the best results with this lens in matter of autofocus i needed to make some autofocus fine tune adjustments within the camera ( i own a K5). Later on the autofocus was good but i cant say this is my sharpest lens. My Sigma 105 is doing very well against the Pentax FA 77 - maybe even better. Well maybe i need to make some more pictures with the FA 77 to have a better picture.
The pentax DA 40mm, as one of my favorite lens in terms of portability didnt impress me with largest aperture settings. Maybe i ll sell it and get the 43mm.

The pentax m 50mm 1.4 did extraordinary well. As my oldest and cheapest lens in my collection it did achieve some spectacular results. Better than my 40mm, thats for sure. I dare to say maybe with 5.6 it achieves better results than my FA 77. Well maybe i have a bad copy

The Sigma 105 is also one gem. In the largest aperture it achieves already very good contrast and sharpness. So not afraid to use this wide open. Unfortunately two times wenn i tested it, with Aperture 5.6 it was not so sharp like 3.5 or 2.8. Maybe i need to check this again.

The Sigma 70-200 in the 200mm range did very good from 5.6. In 2.8 ofcourse it performed worse than all my lenses. But results were expected since it is a zoom lens.


When i did the test i tried always to have the same view from the nutella glass, so i moved back and forward with my tripod. The results are also not 100% precise because of the autofocus of my camera. Maybe next time i use manual focus

Anyway just thought to share this results with you! Any comments or critics are welcome

Cheerz,david

04-29-2013, 12:45 AM   #2
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Sears 50mm f 1:2.0

Very interesting results. I have to say that I am not too surprised, although my copy of the 77 seems a little sharper. I tried something like this and found to my utter horror that one of my old lens left over from film days, the Sears 50mm f 1:2.0 was the sharpest of the lot!
04-29-2013, 01:06 AM   #3
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The FA77 is not so much about sharpness as it is about making beautiful images. And that it does quite well, I think.

The Sigma macros are known for being especially sharp (as are macros in general, anyway) so no surprise there.


I think swapping the DA40 for an FA43 is a good move. You won't lose much by doing so, but you'll gain a lot. I never bought a DA40 because the images I saw never looked outstanding. The FA43 images did. It's not much bigger, and it's a better lens.

I had the M50/1.4 for a brief time, but I sold because it I acquired a K50/1.2 at the same time. However, it was an interesting lens, and I probably would have kept it if not for the K50. The images (partly the colors) never seemed quite normal to me - almost a fantasy appearance - but it could be quite enchanting nonetheless. It would make a good compliment to the FA43. Since one is AF and one MF, you can easily justify owning both. The only problem is you won't be able to justify having a DA*55 as well!

Last edited by DSims; 04-29-2013 at 01:16 AM.
04-29-2013, 02:03 AM   #4
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That Sigma 70-200 is pretty soft, I'd get rid of that asap if I were you.
Also the bokeh from that Sigma 105 is quite poor.

04-29-2013, 03:01 AM   #5
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QuoteOriginally posted by ivanvernon Quote
Very interesting results. I have to say that I am not too surprised, although my copy of the 77 seems a little sharper. I tried something like this and found to my utter horror that one of my old lens left over from film days, the Sears 50mm f 1:2.0 was the sharpest of the lot!
Hi Ivan

well i took another image today (different setup than yesterday) and i took a picture with the 77mm at 1.8 with Manual Focus. I removed the purple fringing with LR, i increased Brightness and contrast (no sharpening). I think it looks quite better now

04-29-2013, 03:12 AM   #6
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QuoteOriginally posted by TOUGEFC Quote
That Sigma 70-200 is pretty soft, I'd get rid of that asap if I were you.
Also the bokeh from that Sigma 105 is quite poor.
well you`re right, i tried the Sigma 70-200 also at 80mm so i can compare it with the FA 77 mm and at 2.8 it is again very soft..



and the same image with the FA 77mm 2.8



i believe a big difference in favour of the pentax. Does the Pentax FA* 200mm perform much better than this?

In my eyes the bokeh of 105 is not so bad but thanks anyway!
04-29-2013, 03:21 AM   #7
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QuoteOriginally posted by DSims Quote
The FA77 is not so much about sharpness as it is about making beautiful images. And that it does quite well, I think.

The Sigma macros are known for being especially sharp (as are macros in general, anyway) so no surprise there.


I think swapping the DA40 for an FA43 is a good move. You won't lose much by doing so, but you'll gain a lot. I never bought a DA40 because the images I saw never looked outstanding. The FA43 images did. It's not much bigger, and it's a better lens.

I had the M50/1.4 for a brief time, but I sold because it I acquired a K50/1.2 at the same time. However, it was an interesting lens, and I probably would have kept it if not for the K50. The images (partly the colors) never seemed quite normal to me - almost a fantasy appearance - but it could be quite enchanting nonetheless. It would make a good compliment to the FA43. Since one is AF and one MF, you can easily justify owning both. The only problem is you won't be able to justify having a DA*55 as well!
thanks DSims

well i have some pictures with beautiful results because of the rendering, but this lens could be sharper.. Imagine that i gave away one DA 35mm Limited and kept this anyway i will try the 43mm if i get the chance :-)

here one sample from the DA 40mm (one of my favorites)
04-29-2013, 04:05 AM   #8
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Have you tried the fine focus setting within the camera? You will need a proper focus test target to be accurate. I found that there is slight differences between the same lens on different cameras. Once set the camera remembers the setting for that lens.

04-29-2013, 04:19 AM   #9
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QuoteOriginally posted by AnnieBell Quote
Have you tried the fine focus setting within the camera? You will need a proper focus test target to be accurate. I found that there is slight differences between the same lens on different cameras. Once set the camera remembers the setting for that lens.
hello Anniebell

i already fine tuned the FA 77 on my K5. Ofcourse i didnt fine tuned all my lenses. THe test i performed today between Sigma 70-200 and the FA 77 was with manual focus (as should the whole test should have been done ofcourse) :-)
Thanks for the info anyway :-)
04-29-2013, 05:53 AM   #10
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QuoteOriginally posted by ddamski Quote
I recently bought the FA 77mm 1.8 and i must say in the beginning i was not so thrilled with the results. To achieve the best results with this lens in matter of autofocus i needed to make some autofocus fine tune adjustments within the camera ( i own a K5)
It's quite possible that you need to fine-tune the AF, especially with a lens as unforgiving as the 77. Get a proper focus test chart, run some tests, and count yourself lucky that your camera allows this, not many brands will offer that option,.
04-29-2013, 05:56 AM   #11
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Well, I don't see why you would get rid of lenses you like due to a sharpness test. One of my favorite lenses is my Sigma 20/1.8 and it's not even close to the sharpest one.
04-29-2013, 06:30 AM   #12
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Well ddamski, I do hope you will succeed to solve your autofocus accuracy problems with your FA77.

But as DSims highlighted above, a good lens is much more than just about sharpness. But it appears that many these days evaluate a lens primarily based on sharpness.

Well, if a particular lens is having actual focus issues or construction problems, leading to unacceptable softness, then yes, you do have a problem on your hands.

But if that is not the case, then sharpness is merely one aspect of a lens' overall performance.

Other things come to play, eg the colour rendering, 3D effect, microcontrast, bokeh character, image 'purity' and so on. These aspects are often overlooked (or unappreciated perhaps). To some extent, an over-reliance on laboratory-based lens testing is contributing to this problem. Test charts do have their usefulness but there is much more to a lens, which can only be detected through actual field usage and experience using the lens to understand its character.

Therefore, to evaluate a lens purely on lab test results, in particular shaprness, is quite dangerous and can well miss the whole point of the lens.
04-29-2013, 06:41 AM   #13
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QuoteOriginally posted by bdery Quote
It's quite possible that you need to fine-tune the AF, especially with a lens as unforgiving as the 77. Get a proper focus test chart, run some tests, and count yourself lucky that your camera allows this, not many brands will offer that option,.
i will give it a shot with a real focus chart. The fine tuning i did was just on subjects so it could not be not 100% accurate Thanks
By the way i know i am lucky with my brand, no option for me to change

QuoteOriginally posted by VisualDarkness Quote
Well, I don't see why you would get rid of lenses you like due to a sharpness test. One of my favorite lenses is my Sigma 20/1.8 and it's not even close to the sharpest one.
I think it depends on what your favorite subjects are for taking pictures. I dont say sharpness is the only criteria. As i wrote before, my DA 40 did perform quite good, i just realized its not the sharpest @ 2.8. For a telephoto like the Sigma 70-200 which weights over 1kg and you cant carry it everywhere, i would like to have some descent sharpness in my pictures when taking some portraits or animal fotos. I consider my self an amateur photographer taking technically good pictures and less artistic

Last edited by ddamski; 04-29-2013 at 06:46 AM. Reason: addition
04-29-2013, 07:09 AM   #14
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Which Sigma zoom is that? I have the old EX DG II 70-200/2.8 HSM macro (not OS) and it fares *much* better than this. Consensus has it that the newer (OS) version is much better.
04-29-2013, 07:29 AM   #15
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That Sigma doesn't look so bad on the 200mm end. That's usually the weakest of all the 70-200s. It's a bit weak on the 80 end though. As Sandy says - some of the Sigma 70-200s aren't that great.
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