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10-20-2011, 06:10 PM   #1
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Photozone MTF 50 Charts.

Hi all,

I've been sweating over lens choices for months and finally decided to lay out the Photozone 10mpx numbers on a combined set of Excel charts. I used the APS-C 10Mpx test results (including a couple of Nikon) because they had the more extensive range of lenses tested and the results are hence more uniform. I've also cheated a bit by calling 1.9 as 1.8 in some cases and entering the 77LTD results on the 70mm line... they still give a reasonable comparison I feel. Single focal-length lenses figures were also repeated on an adjacent focal length column because they were not shown in the graph as a dash. Obviously the graphs can be refined some.

I started this process to combine all the graphs and charts into a more useful summary of the resolutions of the lenses tested for my own usage but felt others may find them informative in some way. I've supplied the charts here as a PDF file for now but may convert them to graphics for upload here as attachments if enough interest occurs.

I was shocked to see my DA* 200 F/2.8 and FA* 300 F/4.5 were NOT as sharp in the center as the Pentax zooms listed at 'working' apertures. The borders are another story apart from the 60-250 however - I'm thinking of selling both and just having a 60-250 for that focal range. I expect selling those two lenses would more than cover the cost.

I am still working on my Excel charts for CA etc but felt that wasn't a priority so much as I tend to use PP for those most of the time. Of course some CA's won't budge in some cases so it's still important to have a decent lens.

When viewing these charts try to keep in mind that:
2350 = Maximum (some numbers were higher.. not sure if they were errors in the tests)
2050 = excellent
1750 = Very Good

I showed the results starting at 1100 on the Y-axis so that the minimum values were displayed but also offered enough scale to show the graphs in more detail than if all were started at zero. When the graphs are displayed from zero on the Y-axis the differences between the lenses look much smaller but it's harder to see some results due to overlaps etc. Try to keep that in mind.

Cheers and I hope you find them useful.

Steve

Attachment 108099


Last edited by bossa; 12-05-2011 at 01:25 AM.
10-21-2011, 12:30 AM   #2
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Well the 60-250mm is an excellent lens, so maybe that makes it different from what to expect. Your messurements are about in line with my expectations. However I did have the feeling that the DA*200 was sharper then 60-250.

Wich sigmazoom did you use? 70-200/f2.8 HSM II or the new 70-200mm/f2.8 EX DG OS HSM?
10-21-2011, 01:07 AM   #3
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Hi Ron, thanks for getting involved.

I could only use the original HSM I as they seem to have skipped over the HSM II (..already owned it before replacing it with the 50-135) in their tests and they never did the OS version in 10mpx that I can see. I have a few test shots with a 60-250 and a Sigma 70-200 OS and the Sigma is sharper between 70 and 180 than the Pentax but there's the extra range to consider. The Sigma is soft at 200 though, so that defeats the reason for these charts, for me at least.


I have a few options the way I see it:
1: Buy the 250 and sell the DA 200 and FA 300
2: Buy the 250 and sell the 50-135, 200 & 300.
3: Buy the Sigma 70-200 OS and sell the 50-135 but keep the 200 & 300. (Not really the outcome I want as I am happy with the 50-135 and the reason for these charts was to find a longer alternative)
4: Just keep what I already have.

It really gets confusing if you lose track of your goal.

Last edited by bossa; 10-21-2011 at 01:18 AM.
10-21-2011, 01:13 AM   #4
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QuoteOriginally posted by RonHendriks1966 Quote
Well the 60-250mm is an excellent lens, so maybe that makes it different from what to expect. Your measurements are about in line with my expectations. However I did have the feeling that the DA*200 was sharper then 60-250.

Which sigma zoom did you use? 70-200/f2.8 HSM II or the new 70-200mm/f2.8 EX DG OS HSM?
From 5.6 and up the 60-250 is sharper than the 200 apart from being slightly softer on the edge of the field at 5.6. I have been trying to not lug so much stuff around with me and right now it looks like the 60-250 and another zoom will cover my walk-around needs and the primes I already have would be better for indoors stuff.

I'm thinking out loud a bit here...

10-21-2011, 06:06 AM   #5
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Well I did use 200mm and 60-250 and the one thing that the zoom can't do is making pictures at f2.8-f3.5.

I now have Sigma 70-200mm/f2.8 EX DG OS HSM and use it at 200mm at f3.2 and not at f2.8 where it is to soft. But still an amazing lens, but not as sharp as the DA*200mm is. That 200mm isn't fast enough for focussing in sports.

I also have DA*55 and almost never use it at f1.4 to f1.8 since I like it when used at f2 or even a little better f2.5. My FA*85mm is already amazing at f1.8, but excellent at f8.
10-21-2011, 06:13 AM   #6
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In my not so scientific test I found that the 60-250mm was amazing. Topping in IQ at 200mm and for the long end at 250mm performing at it's best at f7.1

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/143968-da-60-250mm-f4-test.html

And then I'm going to sell it.
10-21-2011, 01:55 PM   #7
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Selling What?

QuoteOriginally posted by RonHendriks1966 Quote
In my not so scientific test I found that the 60-250mm was amazing. Topping in IQ at 200mm and for the long end at 250mm performing at it's best at f7.1

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/143968-da-60-250mm-f4-test.html

And then I'm going to sell it.
You're going to sell it? The 60-250 or the Sigma? Do you feel that the Sigma is better than the Pentax?


I am still wondering if I should return my Sigma 50/1.4 in favor of the DA 55. I can't help but want weather sealing and the fact that the lens is recessed in a pseudo lens-hood already means is a plus as well. I can't find a lens-hood long enough for APS-C that will work with the Sigma 50. The 77mm filter size makes finding a hood and filter hard work whereas they aren't really needed with the Pentax I feel.

Last edited by bossa; 10-21-2011 at 04:06 PM.
10-21-2011, 01:58 PM   #8
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I did a rough shootout between the 70-200 OS and a 60-250 on a tripod out front of a shop here. I found that the Sigma was better between 70-170 but that the Pentax was sharper from then on. The Sigma had almost no CA as well but did have more purple fringing I felt.

The Sigma and Pentax lenses were aimed at a Logo on an umbrella at an outdoor eatery. The Sigma almost always focused behind the Umbrella though whereas the Pentax was pretty right most of the time. It did make comparisons harder as there were hardly ever any identical zones of focus.


Last edited by bossa; 10-21-2011 at 02:23 PM.
10-21-2011, 02:03 PM   #9
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Nice Shots.

QuoteOriginally posted by RonHendriks1966 Quote
In my not so scientific test I found that the 60-250mm was amazing. Topping in IQ at 200mm and for the long end at 250mm performing at it's best at f7.1

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/143968-da-60-250mm-f4-test.html

And then I'm going to sell it.
Yes, thanks I read your review/test thread a few days ago.

I gather you're saying the 70-200 OS is better for sports due to HSM speed? What price are you looking for for the 60-250 BTW?
10-21-2011, 02:19 PM   #10
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QuoteOriginally posted by bossa Quote
Yes, thanks I read your review/test thread a few days ago.

I gather you're saying the 70-200 OS is better for sports due to HSM speed? What price are you looking for for the 60-250 BTW?
The funny thing about the HSM speed is that it is equal in speed with SDM (with the 60-250), only difference was that the HSM started earlier and thus being fatser at the focussing point.

I'm gonna sell the Pentax, since I'm having two the same lenses now. I do need 300mm/f2.8 so I'm saving up. Already got a buyer.

I used the Sigma now a few times for indoor sports and I do like the results so far. Working with the light that there is (and sometimes iso 5000).

This is the sigma at 200mm and f3.2 pixelpeeping at 100 %
https://dl.dropbox.com/u/20195454/_K5K0428-1.jpg

Last edited by RonHendriks1966; 10-21-2011 at 02:31 PM.
10-21-2011, 02:38 PM   #11
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Sharpened versus Unsharpened.

Here are a few pictures taken with the DA* 200 F/2.8 @ F/7.1 where the two crops show a sharpened and untouched version. I'm wondering just how much that sharpening would improve the numbers in an MTF test. I know the forum degrades the image slightly and I hope the effect is visible so as to make my point.

Original:
Name:  JC - Full.jpg
Views: 574
Size:  39.7 KB

No Sharpening:
Name:  JC - No Sharpen.jpg
Views: 661
Size:  57.9 KB

Sharpened:
Name:  JC - Sharpened.jpg
Views: 553
Size:  82.0 KB

Any thoughts?

EDIT: Actually the difference between the sharpened and non-sharpened versions is much greater here on my computer than on the forum page.

Last edited by bossa; 10-21-2011 at 02:58 PM.
10-21-2011, 02:47 PM   #12
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It is slightly OOF, so never going to make a great picture.
10-21-2011, 03:00 PM   #13
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Maybe I need to do a few focus measurements and correct any issues before jumping the gun.

But I was only showing the difference in the two images really and I'm not sure that it being a tad OOF really diminishes my questions relevance though.
10-21-2011, 03:08 PM   #14
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I'm not at all an expert in those figures, I can read them and understand them but I don't know how this works technically.
10-22-2011, 07:36 PM   #15
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I have updated my graphs in the 1st post.
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