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07-20-2011, 05:39 AM   #1
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adjusting focus

Hello everyone. Foremost if this topic has been covered already (i'm sure it has somewhere) sorry for reposting and could someone please redirect me.

I am fairly new to focus adjusting and I am not sure what I am doing wrong. I am attempting to focus adjust three of my lenses. A Sigma 30mm, a smc DA 21mm F3.2 AL Limited and a smc DA 16-45mm F4.0 ED AL.

I've followed the instructions provided on this website. AF adjustment test chart to help with the Pentax K20D Custom Setting No.34 - Digital Cameras - Zimbio

To my knowledge I did everything correctly (aligned the center of the lens to the center of the focus chart, disabled Image stabilization, opened the aperture etc)

What confuses me is that no matter what I set my focus adjustment to I see no difference in the photos I've taken. I mean I've shot from +10 all the way to -10 and see no differences between either photo.
I realize I must be doing something wrong. Can someone help me out?

07-20-2011, 07:07 AM   #2
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Let's see some examples.
07-20-2011, 09:12 AM   #3
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I think I've read somewhere on this site that you need to turn on/off the camera to "see" the adjustments.
07-20-2011, 12:30 PM   #4
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QuoteOriginally posted by Thesorus Quote
I think I've read somewhere on this site that you need to turn on/off the camera to "see" the adjustments.
I've adjusted one of my lenses and saw the adjustment right away. I actually readjusted it this morning just to make sure and I didn't have to turn the camera off at all to see the difference.

The focusing chart that you linked to is an older version of Yvon Bourques back/front focus adjustments. He has a set of 3 newer charts that are much better and each chart is per type of lens ie: one for telephoto, one for macro and one for standard lenses. He is charging a few bucks for them now but I don't think it's a whole lot.

07-20-2011, 11:24 PM   #5
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Thanks for the feedback guys. Here are some photos to showcase my confusion.

The first picture is taken without any adjustments being made. The second photo is set at a negative 10. (side question. What do the numbers represent when I'm adjusting focus? 10mm?) and the third photo is set at +10.

To my untrained and often wandering eye, they seem really similar if not exactly alike.

I turned off image stabilization but I wonder if there is some sort of image auto correction that I may be forgetting.
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07-21-2011, 12:08 AM   #6
rgk
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If you revisit the K5 menu page after taking the shot is your new setting indicated? I agree there is little/no change in your focus images. Maybe you are accidentally cancelling the adjustment as you back out of the focus fine adjust menu??
07-21-2011, 12:15 AM   #7
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RGK, I also thought that was the problem. The setting does save after I re-enter the menu.. This happens with all three of the lenses i'm attempting to fine focus.
07-21-2011, 01:05 AM - 1 Like   #8
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In that case, it might be interesting to look at the detailed EXIF data in PhotoME to see what AF Adjustment was actually applied to the lens/image.

(actually now I'm not certain where to find that info in PhotoME, maybe that was some bad advice on my part!)


Last edited by rgk; 07-21-2011 at 01:15 AM. Reason: updated info
07-21-2011, 01:35 AM   #9
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Oh good I thought it was just me, I get the same result it does not seem to make any difference how I adjust, the images all look the same.
07-21-2011, 02:45 AM   #10
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kmount,
besides mentioned advises you'd also note, that AF adjustment only affects phase-detect AF (when you work with the viewfinder), it doesn't work with contrast-detect AF (when you're in LV mode).
It's also worth changing AF to central point only.

Good luck,
Zig
07-21-2011, 02:54 AM - 1 Like   #11
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QuoteOriginally posted by rgk Quote
In that case, it might be interesting to look at the detailed EXIF data in PhotoME to see what AF Adjustment was actually applied to the lens/image.

(actually now I'm not certain where to find that info in PhotoME, maybe that was some bad advice on my part!)
Just type AF in the Filter Bar at the bottom,. and AF Adjustment will show up.
07-21-2011, 03:04 AM   #12
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The only lens out of the lenses that you are mentioning that I can guarantee you will work with AF adjustment is the DA21.

Zooms by Pentax usually ignore the adjustment.
Lenses by other manufacturers as well.

This is speaking from my experience,
07-21-2011, 03:08 AM - 1 Like   #13
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That focus chart you are using is just absolutely terrible The AF could lock on anywhere so it's the worst possible chart to use for AF calibration.

For a much better chart have a look here Jeffrey Friedl's Blog Jeffrey’s Autofocus Test Chart
07-21-2011, 05:17 AM - 1 Like   #14
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I agree, the chart you were using looks pretty hopeless.

For a choice of charts and some tips, see my AF adjustment hints.
07-21-2011, 08:56 AM   #15
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Yikes! I didn't realize the chart I was using was so outdated and useless. Let me reshoot and get back to you guys. Perhaps my problem was that my camera's autofocus had too many things to lock onto.
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