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03-30-2014, 10:30 PM   #1
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Pentax Nifty 50 MTF charts

Just came across this imatest comparison of Pentax 50mm lenses including A50/1.4, F50/1.7, Tak 55/1.8 etc.

Results are surprising - A50/1.4 is the winner followed by Tak 55/1.8. There is a general opinion that F50/1.7 is the sharpest but not according to this test. Here are two MTF 50 charts from the comparison, more on the above mentioned website.

Center


Edge


Here is another not so exhaustive chart and results seems to be in agreement.

Interesting!!!

03-31-2014, 12:38 AM   #2
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They did a hell of a job picking colors for that graph

This is great news for me. I have a F 50mm 1.7 as my go to 50 and just today bought a FA 50mm 1.4. Being the pixel peeper that I am I was initially hesitant to buy it just because everybody says the 1.7 is sharper.

Last edited by geomez; 03-31-2014 at 12:46 AM.
03-31-2014, 12:42 AM   #3
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Yeah too hard to see, appreciate their work though.
03-31-2014, 03:27 AM   #4
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I saw this a while ago. I have a A 50 f1.7, A 50 f1.4, SMC 55 f1.8 and Helios 44-2.
I agree that the A 50 f1.4 seems sharper than the A 50 f1.7 both for peak sharpness and at equivalent apertures (most of the range anyway - some settings are nearly identical). Sure wide open the f1.7 is a bit sharper than f1.4 but not hugely and with both at f1.7 I found the f1.4 to have a slight edge on the f1.7 if memory serves me correctly. By f2 the A 50 f1.4 is better for my copies anyway.
Maybe the F / FA 50 f1.7 are sharper than A version or maybe I just have a really good A 50 f1.4 but that is what I found.

I was a bit surprised about the SMC 55 f1.8 because mine has produced some great results but then when you look at the charts its sharpness around f5.6 is very impressive across the frame.

03-31-2014, 03:39 AM   #5
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I have good color vision and can barely see the difference....
03-31-2014, 03:52 AM   #6
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Well, the only of my fifties included here is the Helios. And all of the others are at least as sharp. I need no charts to tell me they are all plenty good enough
03-31-2014, 04:01 AM   #7
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Certainly a good comparison, I have a K 55mm f/1.8, and I love its pictorial rendering. Though you're missing the SMCP-K 50mm f/1.2.
03-31-2014, 05:12 AM - 2 Likes   #8
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How anyone managed to take photos before MTF graphs I'll never know.

03-31-2014, 05:56 AM - 1 Like   #9
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QuoteOriginally posted by tromboads Quote
How anyone managed to take photos before MTF graphs I'll never know.
They used the MIL-STD-150A resolution test chart
03-31-2014, 05:58 AM   #10
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So.. Helios 44-2 wins at f5.6? I don't know, I think this chart is a little odd. I would chalk up a lot of this to sample variation between individual lenses.
Also, perceived "sharpness" is not only resolution, but things like contrast, colour rendering, DoF, and lack of CA also make the photo appear "sharp"
03-31-2014, 07:46 AM   #11
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I have a few of the lenses except 3 of them.
To me, they are all sharp enough.
None of them starkly fails in the context of sharpness to be obvious w/o close scrutiny or comparison.

What sets the cheaper Pentax f1.7 and f2 50mm apart is the hexagonal aperture once stopped down even 1 stop.
To me, it can be very distracting when there are OOF highlights in the photo, which will turn out to be hexagonal.

For that, I would recommend just going straight for a SMC tak 55/1.8 (for low cost) or a 50/1.4 (if one can afford and get the f1.4 benefit too)
Else, just get the new DA50/1.8

Last edited by pinholecam; 03-31-2014 at 08:32 PM.
03-31-2014, 10:22 AM   #12
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QuoteOriginally posted by Na Horuk Quote
So.. Helios 44-2 wins at f5.6?
Sure! Why not?

The question in my mind is the sensor resolution for the test. Also, why the funky colors and no edge data for some lens/aperture.


Steve

Last edited by stevebrot; 03-31-2014 at 10:28 AM.
03-31-2014, 11:25 AM   #13
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In practice for my use, at f/5.6 and above (I usually shoot f/5.6 ~ f/8) virtually any fifty is good enough. The issue is always focusing.
03-31-2014, 12:01 PM   #14
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The charts are awesome even if the colors are wonky. I just read off / count off the colors from right to left. Industar is pink-ish and Helios is orange-ish. Just follow the legend and bars backwards.

I was also surprised by the Helios being so sharp! It even beats out the A 50mm f/1.4. Well, the answer is obvious. All of my pictures from before today with any lens other than my Helios are just rubbish. I'm going to dig a pit in my backyard and toss all my glass in there. Maybe even burn 'em all!

No, not really.
03-31-2014, 12:18 PM   #15
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Boris - send all your inferior 50's to me. I have a special 'lens disposal bag' in my closet. You'll never see them again. Really.
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