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08-12-2009, 04:07 PM   #1
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K-7 with FA50/1.4 focus test?

Hi All,

Thanks for your replies of my former posts. Here is some upgrade for the front focus issue with K-7 and FA 50/1.4.

I just received my second body from Amazon (Great replacement policy!) but this one again has front focus with FA 50/1.4 and DA 16-45. The serial numbers of the two are: 3885138 and 3880695 and was produced on Jul 1 and 3.

Wonder if any of you with the same gears did any focus test. Could pls kindly take some and share your results? It would be great if you post your conclusion with a test figure and serial number. Thank you very much!

I just wonder why I got so bad luck or am I doing anything wrong?

Thanks,
Tony

08-12-2009, 05:43 PM   #2
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You are aware that you can adjust for front and back focus with the K7?
08-12-2009, 06:26 PM   #3
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You need to calibrate each lens to the camera body. Below are some focus tests with my K-7. Once you see how each lens behaves with the K-7, you dial in the right amount of front or back focus for each lens individually.

50 F1.4 wide open


300 F4 wide open

Last edited by jbcampbell; 08-12-2009 at 07:05 PM.
08-12-2009, 07:10 PM   #4
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It seems I got 2 bad lucks. Mine is not good with AF adjust -10.

Tony

08-12-2009, 07:17 PM   #5
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It's pretty bad when they use electronics to compensate for variations between lenses.

Are they saying that since they can't get their lenses right that it's just better to fix it in camera? Essentially telling people with "Older cameras" AKA the K10D to keep swapping lenses until we find one that matches the body?
08-12-2009, 07:35 PM   #6
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There are 2 things I have to say about the FA50mm f/1.4 ( I love the lens, by the way - super sharp, after the focus adjustment).

At f/1.4 to f/2.8, the DOF is so shallow it just takes a small error by the photographer or camera to end up focusing on something other than the subject...Its happened to me before.

On the K100D I did have to send back the body to calibrate the focus together with the lens. Not a big amount, but enough to be annoying at large apertures.

How long have you had the FA50mm f/1.4 ? Have you tried it on another body (not K-7 ?)
One of the variables is time and usage. A lens which was "perfect" three years ago may need focus adjustment now, especially after a few thousand shots.
08-12-2009, 07:38 PM   #7
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QuoteOriginally posted by sebberry Quote
It's pretty bad when they use electronics to compensate for variations between lenses.

Are they saying that since they can't get their lenses right that it's just better to fix it in camera? Essentially telling people with "Older cameras" AKA the K10D to keep swapping lenses until we find one that matches the body?
There are variations in all lenses, this isn't specific to Pentax, most high end DSLRs offer the ability to tweak focus with in camera settings. I think it's just an evolution of the product. With digital "pixel peepers" it's easier to uncover the variations in the lenses so the manufacturers were pressed to come up with a solution.
08-12-2009, 08:02 PM   #8
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Well, this is a new 50/1.4. I only have two K-7 bodies to test, all shows front focus more or less and with my used DA 16-45 lens at 45.

08-13-2009, 06:40 AM   #9
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QuoteOriginally posted by fulcrumx29 Quote
Hi All,

Thanks for your replies of my former posts. Here is some upgrade for the front focus issue with K-7 and FA 50/1.4.

I just received my second body from Amazon (Great replacement policy!) but this one again has front focus with FA 50/1.4 and DA 16-45. The serial numbers of the two are: 3885138 and 3880695 and was produced on Jul 1 and 3.

Wonder if any of you with the same gears did any focus test. Could pls kindly take some and share your results? It would be great if you post your conclusion with a test figure and serial number. Thank you very much!

I just wonder why I got so bad luck or am I doing anything wrong?

Thanks,
Tony
Strange you sure it's the body and not the lens ? My FA50 1.4 I bought from Adorama last year is serial 5713640 no probs with K-7 with both old and new firmwares.
08-13-2009, 06:54 AM   #10
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I am glad I spent my whole life using MF cameras and lenses so I don't end up being an AF weenie.
08-13-2009, 07:39 AM   #11
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QuoteOriginally posted by jogiba Quote
I am glad I spent my whole life using MF cameras and lenses so I don't end up being an AF weenie.
Yep, and I'm glad I spent my whole life walking everywhere so I don't end up being an Automobile weenie.
08-13-2009, 03:17 PM   #12
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Hi All,

Thanks for your comments. Here are some samples: left are phase detective, and right are live view focus. All figures are with AF fine tune at -10 for individual lenses.

Picasa Web Albums - Jian - K-7 focus test

You can see the front focus is most obvious on FA 50 and weakest on DA 16-45 at 16.

Could you pls check them for me to see if the problem is from lens, camera or me (am I too picky)?

Thank you very much,
Tony
08-14-2009, 12:02 AM   #13
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What I can see is that your test target is not 100% aligned with your camera. It has to be. And this target is probably to close to the camera, too. For a 50mm lens, you should at least have 125cm distance, but more is better.

I tried several lenses myself with this target and got results everywhere. Then I borrowed a Lensalign and got consistent results around zero adjustment. But my FA50/1.4 was still way off and needed -10
08-14-2009, 01:22 AM   #14
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have you tried manual focus tests with both FA50 1.4 ? are they spot on compared to AF ?

tried resetting all menu settings to factory default and doing the tests again maybe the micro AF adjustments are stuck or not working ?

Do the FA50 1.4 both work on another pentax body i.e. K20D ? Maybe go into a local store with both lens and test in store with another pentax body ?


edit: Just retested my FA50 1.4 on K-7 v1.01 firmware, I noticed with Horizon Correction enabled in menu, my FA 50 1.4 AF focus was a bit off depending on subject matter it front or back focused slightly, disable Horizon Correction disabled, AF was spot on.

Last edited by eva2000; 08-14-2009 at 02:02 AM.
08-14-2009, 05:29 AM   #15
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Wonder what the odds are that two different, new, K7 bodies would have the same problem with the same lens and that the lens wouldn't be at fault? I'd hazard a guess that those odds would be somewhere between infinitesimal and zero, but a lot closer to zero.
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