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06-16-2011, 11:50 AM   #16
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QuoteOriginally posted by starstuff Quote
I also plan to do a more careful A:B comparison of the 21mm on the K20D body and the K5 body. Stay tuned on that one
What firmware are you on?
Many people have reported AF fine tuning problems getting solved by newer FW revisions.

You can check you firmware revision by pressing the menu button while turning on the camera.
My K-5 vis on revision 1.03.
Link is here: Latest K-5 Firmware Update : Software Downloads : PENTAX

Cheers, Bert

06-16-2011, 03:36 PM   #17
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A-B test: K20D sharper?

I have firmware version 1.03 installed, thanks Bert. I installed it as soon as I got the camera.

So here's an A-B test. I think the K20D wins.

Here's what I did: I shot pretty much the identical image in my back yard with the same lens, once with the K20D and once with the K5. In each instance I used point AF, pointed at the bush in the background, right in the center of the image. Granted that it's a complex subject with its many layers, but again, I did the same thing with the two cameras for comparison. F-stop and shutter speed are approximately equal (not possible to be exactly equal: the K5 and the K20D have different f-stops), same ISO. And in each instance, images were shot in RAW and converted to full-sized jpg with no post-processing except Lightroom camera corrections, shake-reduction turned on.

I couldn't figure out how to post the photos here, so I've put them on Flickr, and linked to the full-sized image so you can look closely:

The K20D Shot:
All sizes | This is a test: Shot with K20D | Flickr - Photo Sharing!

The K5 shot:
All sizes | This is a test: Shot with K5 | Flickr - Photo Sharing!

If you have a moment, please take a look. Am I crazy? Is the K20D image substantially sharper?

Thanks again for your input on this.
06-16-2011, 04:25 PM   #18
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Star, I would say that the K20 is not significantly sharper, and I'll give you a couple reasons why. Most importantly, I think, is the fact that these are NOT the same shots. That is, as a comparison between two lenses, the pics you've linked to are soooo vastly different as to not even be a fair comparison. You used the same lens set on the same focal length? And you didn't crop either image, specifically the K20D? In all honestly, I would say, with the included photos, that this is an apples to oranges comparison, not an apples to apples comparison. So given that, I return to my verdict: The K5 is not sharpen or softer than the K20. In fact, the tree on the left is much sharper and more in focus in the K5 shot than the K20 one.

If you want a real apples to apples comparison, get a tripod and leave everything the same, including iso, shutter speed, and aperture.
06-16-2011, 04:32 PM   #19
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I used the same 21mm prime on both shots, didn't crop or in any way edit either of the shots -- and it's not possible to use identical f-stops, since with the K5 f-stops go from 5.6 -> 6.7 -> 8.0, and with the K20D from 5.6 -> 6.3 -> 7.1. The difference though should favor the K5 ever-so-slightly, since I had to use a smaller aperture (6.7 vs. 6.3) with the K20D.

The tree on the left is a bit sharper with the K5, but I used point AF with both cameras with the very center of the viewscreen (and the red dot) directly on that bush in the rear center of the frame.

I know I should use a tripod to get the comparison exact, but I don't have a tripod. :-)

06-16-2011, 05:15 PM   #20
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Without the tripod, did you stand in the exact same spot? The K5 shot is definitely wider than the K20. Or is it just me?
06-16-2011, 05:27 PM   #21
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QuoteOriginally posted by starstuff Quote
and it's not possible to use identical f-stops, since with the K5 f-stops go from 5.6 -> 6.7 -> 8.0, and with the K20D from 5.6 -> 6.3 -> 7.1
Sure it is. Change your EV steps from 1/2 to 1/3 or vice versa. And Tele Pathic is right. If you have any chance of make any type of real comparison, you need to take the exact same shot. You might as well have taken pictures of an acorn lying on the ground and a sailboat in rough seas.
06-16-2011, 05:51 PM   #22
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To me, the K5 shot looks slightly better, but everyone is correct, the shots are too different. As much as I hate brick wall shots, this is when you'd want to take one.

Oh, and there's a USB port on these cameras? Who knew?
06-16-2011, 09:27 PM   #23
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To compare between two different cameras/lenses you must be more consistent and it would require a more scientific approach.

The lack of a tripod should not prevent you to set up your cam(s) to achieve uniformity. Be inventive, use a table, chair, rubbish tin, ladder or whatever you might find in or around your house.

Then point your cam at a more "graphic" and immovable target (not a tree or bush). If you shoot under natural sunlight, the time it takes to re-arrange your equipment could be long enough for the sun to move a fair bit which in turn will change the appearance of your target. The differences between equipment you are trying to evaluate are often quite small and those little changes in shooting conditions can and will give you a false result.

Nonobservance of the aforementioned will only allow a subjective evaluation and not the objective one you are seeking. So, give us and yourself a better chance.


06-18-2011, 08:24 AM   #24
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Thanks for your input and words of reassurance, everyone. It's taken me time to test and fiddle, but I'm now convinced that everything is A-OK and that with AF fine adjustment, there's nothing wrong with my K5 body, as usual the fault was with yours truly, the photographer. I always think about that line from WAITING FOR GODOT: "Just like a man for you: Blaming on his shoes the faults of his feet."

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