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11-26-2010, 04:34 AM - 1 Like   #136
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QuoteOriginally posted by JohnBee Quote
Other than that, I've been thinking of conducting some controlled tests with a K-5 and D7K using the same lens. And I wondered if anyone thought of an M42 Super Takumar(SMC) 55/1.8 would be suitable for the task?

I plan on shooting some resolution charts and various color patterns with the hope of establishing some form of conclusiveness with regards to the differences between both systems. The target date is this weekend, so if anyone has any suggestions and/or ideas to add, I'd love to hear them.
JohnBee, be careful.

The project is full of traps. Even if you manage to have the exact same lens, you need to have identical lighting and exposure setting, raw conversion, aperture (now, that's easy), stability and focus.

So I recommend using the same raw converter and settings, white balance to a gray card, white spot manually adjusted to a given level like 90% (by using the appropriate exposure compensation in raw conversion). Don't use a tripod. Clamp the camera to a rock solid table, preferrably stone, not wood.

And most importantly, use a focus series with 1cm steps and select the sharpest in the series, even extrapolate the sharpest point. Relying on AF, contrast AF or even zoomed manual LV AF isn't precise enough for a comparative study. And with a lens with spherical aberration (and all 50s from the past have it) manual focus is completely off the mark. That's the most tricky part and failing here ruins your study.

Last but not least, use your lens' center sweet spot. That's typically wider than f/5.6.

The difference between doing everything in an optimal way and a typical shot is about 1px blur width difference, like going down from 2px to 1.2px. So, this is huge. OTOH, if not in the studio, this kind of artificial resolution test is not very relevant for that reason. But if you want to learn about the AA filter differences, that's the only way to go.

BTW, AA filter effects become very visible when shooting the zone plate chart. Better than the ISO test chart. I've a test chart available for download.

11-26-2010, 08:05 AM   #137
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What about K-r, does it also have the stronger AA filter compared to k-x ? DXOmark had slightly different results compared to k-x
11-26-2010, 08:11 AM   #138
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QuoteOriginally posted by falconeye Quote
...
The difference between doing everything in an optimal way and a typical shot is about 1px blur width difference, like going down from 2px to 1.2px. So, this is huge. OTOH, if not in the studio, this kind of artificial resolution test is not very relevant for that reason. ...
If such extreme care is needed to reveal small differences in resolution, how relevant are these tests to photographers who
  • Do not use tripods
  • Rely on autofocus
  • Use apertures which may not be their lenses' sweet spots
  • Raise ISO when needed
  • Etc.
Are we fussing about small differences that can only be revealed in ideal studio conditions, but which are nearly impossible to achieve in the field?

Jeff
11-26-2010, 08:13 AM   #139
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QuoteOriginally posted by Jeff Charles Quote
Are we fussing about small differences that can only be revealed in ideal studio conditions, but which are nearly impossible to achieve in the field?
that would be spot on

11-26-2010, 08:39 AM   #140
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QuoteOriginally posted by ogl Quote
Don't you see that even 100% crop is a bit blurry?
The 50% crops of the photos in your album are more blurry... These pictures are not 100% perfectly sharp, but they are sharper than the results from your 10mp CCD AND if they were perfectly sharp, there would be rather unpleasant artifacts. If you were to print this pictures, it would be very sharp. When was the last time you printed a picture? Why do you demand this absurd sharpness for your photos of wildlife and flowers? Did you even read that link to the leica forum?
11-26-2010, 09:05 AM - 1 Like   #141
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I think at this point, there is only one thing left to say about this thread:



11-26-2010, 09:07 AM   #142
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QuoteOriginally posted by falconeye Quote
I've a test chart available for download.
Would you give a hint where to find this test chart? The download section on your homepage is empty ...
11-26-2010, 09:46 AM   #143
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MY FINAL VERDICT: K-5 has good IQ and not bad sharpness.
If somebody need more sharp photos - just add a bit sharpness in converter.
Not much.
For example, I use 30-40@0.8 in LR for K200D. For K-5 - 45-50@0.8 is really good.

I'm waiting a support of K-5 in C1Pro.


Last edited by ogl; 11-26-2010 at 09:55 AM.
11-26-2010, 10:11 AM   #144
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QuoteOriginally posted by ogl Quote
Don't you see that even 100% crop is a bit blurry?
There is fuzzy, okayish, sharp, tack-sharp and ogl-sharp. An image is ogl sharp if ogl's eyes start bleeding when looking at it.

QuoteOriginally posted by Jeff Charles Quote
Are we fussing about small differences that can only be revealed in ideal studio conditions, but which are nearly impossible to achieve in the field?
Jeff understood the purpose of my post.

But this thread is a pixel peeper's world, isn't it?

Sharpness in the field is a whole other story which I need to write about. It's all about not squeezing a system's tolerances to their edges.

QuoteOriginally posted by Rainer Dynszis Quote
Would you give a hint where to find this test chart? The download section on your homepage is empty ...
My homepage actually has no download section.

I meant my testchart gallery available here:

and linked e.g., from a paper I thought it becomes increasingly annoying I am keeping citing it

The ISO test chart contains material from ISO 12233 Test Chart which is why I didn't make my modified version available for download.
11-26-2010, 11:04 AM   #145
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QuoteOriginally posted by falconeye Quote
There is fuzzy, okayish, sharp, tack-sharp and ogl-sharp. An image is ogl sharp if ogl's eyes start bleeding when looking at it.
Very funny. I hope that Ogl has a sense of humor. I hate to bash people, unless they are truly obnoxious. Ogl is annoying, because of his rigid perfectionism, but not obnoxious.

Rob
11-26-2010, 11:56 AM   #146
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QuoteOriginally posted by ogl Quote
Who want to make sharp photos. You are wrong. I've never make pictures of test chart.
You're citing Klaus' fining that the vertical sharpness of the K-5 does not substantially exceed--even thought it does exceed--the K10D on test charts. How does this equate to the K-5 not being able to take sharp pictures?

If "sharpness" is your one pursuit, then you are welcome to it--and a larger sensor is probably going to be your goal rather than an upgraded small sensor.

Of course, if you have evidence that the K-5 is worse at producing sharp images than, say, the K-7, I'd be interested in seeing it. But only slightly higher vertical MTF values isn't enough to convince me that the K-5 is flawed.
11-27-2010, 01:38 AM   #147
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QuoteOriginally posted by falconeye Quote
I meant my testchart gallery available here:
Thanks for the link.

BTW and apropos, on photoble there's a picture which I think would be a nice demo shot to illustrate what the K-5 is capable of: impressively sharp at full resolution (i.e. even for pixel peepers) without any obvious sharpening artifacts.

Assuming that the photographer had to know what he was doing to achieve this result, it probably also illustrates the old adage that it's not the arrow, it's the indian.
11-27-2010, 02:57 AM   #148
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QuoteOriginally posted by Rainer Dynszis Quote
it's not the arrow, it's the indian.
Sorry, that adage is outdated. The modern version is "It's not the tool, it's the toolmaker".

P.S.: I tried to attribute to a forum member because I picked it up some time ago from a member's sig, but I couldn't find it.
11-27-2010, 03:40 AM   #149
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QuoteOriginally posted by robgo2 Quote
Very funny. I hope that Ogl has a sense of humor. I hate to bash people, unless they are truly obnoxious. Ogl is annoying, because of his rigid perfectionism, but not obnoxious.

Rob
All of us has OWN SHARPNESS.
11-27-2010, 05:05 AM   #150
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QuoteOriginally posted by Class A Quote
It's not the tool, it's the toolmaker
Or an alternative formulation I heard of recently, courtesy of an impressive Australian K-x photographer I came across via flickr and whirlpool: 'It's not the wand, it's the wizard'.
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