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11-02-2015, 01:18 AM   #1
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AF micro adjustment.

I have always been afraid of try this. And because of the obvious warnings I have stayed away.
But one always has to grow and learn right?
Since i have a second camera body I decided to check the AF micro adjustment on my new K-3 camera.
This way I have a backup, my K-30 if I screw it up.
One thing though is that there are so many threads with different opinions on how to do this.
I did find one article that suggested two ways of doing this. But unfortunately I dont have accessing to the calibrating equipment that were mentioned.

I did how ever find this on youtube and I thought i had try it out on my K-3.


PS I didnt do any adjustment at this stage. Just tested.

My concerns

1. Can this work for Pentax?
2. When I tested this procedure on my K-3 and Tamron 28-75 f2.8 combo, It was back focusing really badly at the wide end (28mm). 50mm and 75mm were sharp. How does one correct the wide end with a pentax? As you can see in this video you can adjust at wide and a tele end for a canon.


Also it will really be nice to have a video for AF microfadjustment for Pentax on our Youtube channel. Adam?

11-02-2015, 01:45 AM   #2
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QuoteOriginally posted by Culture Quote
2. When I tested this procedure on my K-3 and Tamron 28-75 f2.8 combo, It was back focusing really badly at the wide end (28mm). 50mm and 75mm were sharp. How does one correct the wide end with a pentax? As you can see in this video you can adjust at wide and a tele end for a canon.
You can't. There's only one setting for each lens on Pentax cameras, so it can be a balancing act for zooms.

If you do decide to make fine adjustments to the AF, I strongly recommend having a reliable test target. Also, unless you're experiencing consistently inaccurate autofocus with a certain lens, I wouldn't bother making any adjustments at all (if it ain't broke, don't fix it ).

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11-02-2015, 02:50 AM   #3
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QuoteOriginally posted by Culture Quote
I have always been afraid of try this. And because of the obvious warnings I have stayed away.
But one always has to grow and learn right?
Since i have a second camera body I decided to check the AF micro adjustment on my new K-3 camera.
This way I have a backup, my K-30 if I screw it up.
One thing though is that there are so many threads with different opinions on how to do this.
I did find one article that suggested two ways of doing this. But unfortunately I dont have accessing to the calibrating equipment that were mentioned.

I did how ever find this on youtube and I thought i had try it out on my K-3.

How to perform AF Microadjustment - YouTube

PS I didnt do any adjustment at this stage. Just tested.

My concerns

1. Can this work for Pentax?
2. When I tested this procedure on my K-3 and Tamron 28-75 f2.8 combo, It was back focusing really badly at the wide end (28mm). 50mm and 75mm were sharp. How does one correct the wide end with a pentax? As you can see in this video you can adjust at wide and a tele end for a canon.


Also it will really be nice to have a video for AF microfadjustment for Pentax on our Youtube channel. Adam?

My 17-50 Tamron focused differently depending on the choosen focal length AND aperture. I had to send it to the repair shop so they could adjust it at the different focal lengths. I think they had three possible settings in the lens fimware.

This video may make it easier to do the fine tuning. Depending on the focal length you should use different distances when adjusting.

11-02-2015, 05:14 AM   #4
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AF fine adjustment is not something to be scared of, as it's only a software parameter that's being changed (which in turn controls hardware) and can easily be reset.

AF adjustment of zooms is tricky, however, insofar as you can't make multiple adjustments to suit various conditions throughout the zoom range, so you have to decide (a) whether to check at short/medium/long focal lengths and average the results, or (b) identify and adjust at the focal length you use most frequently. Either way it's a compromise, but hopefully if you shoot at, say, f8, dof will help.

11-02-2015, 09:05 AM   #5
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QuoteOriginally posted by Tjompen1968 Quote
[...] This ["Dot-Tune"] video may make it easier to do the fine tuning. [...]

DotTune: Autofocus fine tuning in under 5 minutes - YouTube
Interesting. Has anyone tried this on a Pentax DSLR yet (one, of course, equipped with AF Fine Adjustment) ?
11-02-2015, 10:24 AM   #6
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QuoteOriginally posted by fwcetus Quote
Interesting. Has anyone tried this on a Pentax DSLR yet (one, of course, equipped with AF Fine Adjustment) ?
Yes, you can use Dot Tune on Pentax dSLRs and it works pretty much as advertised, though I would caution that care should be taken to make sure that the reference focus in live view be made with the lens fully open. This is easy enough for lenses having aperture rings, but can be a problem for lenses that don't. Depending on light, the camera may partially stop the lens down in live view.


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11-02-2015, 12:48 PM   #7
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QuoteOriginally posted by stevebrot Quote
Yes, you can use Dot Tune on Pentax dSLRs and it works pretty much as advertised, though I would caution that care should be taken to make sure that the reference focus in live view be made with the lens fully open. This is easy enough for lenses having aperture rings, but can be a problem for lenses that don't. Depending on light, the camera may partially stop the lens down in live view.
Thanks for that tip.Steve. [Although, in my particular case, the DA 55-300/4-5.8 is my only "ringless" lens (not counting a couple of fixed-aperture mirror lenses).]
11-02-2015, 01:02 PM   #8
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What a great link, thanks! Anyone have any tips on how to get your camera parallel to the target?

Thanks

Randy

11-02-2015, 01:19 PM - 1 Like   #9
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QuoteOriginally posted by fwcetus Quote
Thanks for that tip.Steve. [Although, in my particular case, the DA 55-300/4-5.8 is my only "ringless" lens (not counting a couple of fixed-aperture mirror lenses).]
Use the DOF preview when setting the focus. It should open up when you do this. (If you have f-stop set to it's lowest ofcourse...)
11-02-2015, 07:26 PM   #10
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QuoteOriginally posted by slip Quote
What a great link, thanks! Anyone have any tips on how to get your camera parallel to the target?

Thanks

Randy
I use a flat target and measure from each side of the target to the surface of the rear LCD. Some users place a carpenter's tri-square (held by a helpful assistant) aligned with the center of the target. Level the camera and sight down the edge of the square to true up.


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11-02-2015, 10:42 PM   #11
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Thanks for all advice. The DotTune definitely looks detailed.
11-03-2015, 03:52 AM   #12
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I use live view to test my lenses to see if they need focus adjustment. It is pretty simple and I have been pleased with it: AF microadjustment for the 1Ds mark III, 1D Mk3, 5D Mk2, 7D, 1D X.

If you have a zoom that focuses differently at different focal lengths the only thing to do is to send it in to the manufacturer. Sigma does have a dock now for their newest lenses that can adjust at a few different focal lengths, but there isn't anything similar for Tamron.
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