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06-27-2008, 07:43 AM   #1
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K20D vs K200D 100% Crop Test - The Results may Surprise You

Curiosity struck again:

Edit -- Images shot in PEF, converted to JPEG 100% quality using lightroom2 64bit Beta. Developing settings for both cameras exactly the same (I triple checked this).

Setup:

Test chart pinned to wall, illuminated by flourescent lamp. Cameras placed on firm surface with exact positions. Focal point center. 2 sec timer. HIGH ISO noise OFF (irrelevant) and low shutter noise OFF or AUTO (also irrelevant).

Lens: DA* 50-135 mm, autofocus, f/5.6
ISO 100



50mm Crops

K20D Center (75mm)



K200D Center (75mm)




K20D Edge (50mm)



K200D Edige (50mm)



----------------------

I'm not sure what to think of the results. To me, the K200D simply looks better.
In 100% pixel peeping the full images, my textured wall stuck out more with the K200D. I thought at first perhaps the AUTO slow shutter NR of the K20D was kicking in, but my shutter speeds aren't slow enough to allow this. Even the paper's texture in the K200D is clearly more visible than the K20D's, and it's a smaller image.

I tested this twice with this lens. I also ran the test with the Tamron 28-75mm at F/5.6 and got the same results.


Either I don't have the lens required to resolve the K20D, or the K200D's image is simply a bit sharper (maybe due to "smaller is sharper"), or my test procedures are thrice faulty.

I was surprised, to say the least.

I've contacted Pentax to see if perhaps there is anything to improve my methodology. I'm curious to hear their response.
I've also considered that *maybe* the lenses are slightly FF / BF with the K20D, but seeing as how I was extremely diligent in making sure I was at 90 degrees to the chart, and the images for the K200D were sharper with TWO lenses, I don't see how this could be true.


Last edited by cputeq; 06-27-2008 at 07:55 AM.
06-27-2008, 08:00 AM   #2
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Because auto focus was used it is my humble opinion that you should make absolutely nothing of the results. It is conceivable with that variable in play a repeat test could yield opposite results. It all depends on when the focusing algorithm in that camera, at that exact moment, told the focusing motor to stop turning.

To me all cameras, not just Pentax, auto focus the way farmers park their pickups: "just get it on the property". Put another way, auto focus is more like auto-somewhat-focus.
06-27-2008, 08:04 AM   #3
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crop the K20D image so that the SIZE is identical to the K200D then tell us what you think....
06-27-2008, 08:16 AM   #4
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QuoteOriginally posted by Parallax Quote
Because auto focus was used it is my humble opinion that you should make absolutely nothing of the results. It is conceivable with that variable in play a repeat test could yield opposite results. It all depends on when the focusing algorithm in that camera, at that exact moment, told the focusing motor to stop turning.

To me all cameras, not just Pentax, auto focus the way farmers park their pickups: "just get it on the property". Put another way, auto focus is more like auto-somewhat-focus.
Good idea. I tested again using manual focus, 70mm (50mm too small to see).



Much better results.

Interestingly, I didn't have "focus confirmation beep" when I took this.

My K20D might just be slightly off on focus with both lenses, an interesting development. More to come.

06-27-2008, 08:45 AM   #5
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Issue resolved. Needed a backfocus adjustment.
06-27-2008, 09:11 AM   #6
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Okay, now you can test them again....
06-27-2008, 02:56 PM   #7
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QuoteOriginally posted by cputeq Quote
Issue resolved. Needed a backfocus adjustment.
Hi, cputeq

My 20D is also backfocusing a bit. But once I adjusted it became razor blade sharp.

Radu
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