My current method to determine AF-Fine Adjust values

Started Mar 26, 2013 | Discussions thread
kaedepics Regular Member • Posts: 327
Re: Try to use the f/2.8 AF-sensor of the K-5 IIs

Kerusker wrote:

kaedepics wrote:

I have had my da*200 for a 6 months now. Recently the images have seemed a little soft so I thought maybe I should adjust focus. Using a printed focus chart, tripod , 2 sec timer, shot at 45 degrees I found that +7 was needed and it seemed better. Then I read this post and realized that when I did the test I had been much too close to the target. 8 feet. So I did it again.

My set basically the same but 90 degrees, at a distance of 17 feet and the target was my laptop screen diplaying a focus target at 100%. I tried the dot-tune method. First attempt I found the hexagon focus indicator stayed lit in the range of -4 to + 9

This gives about a +3.5 but after rechecking several times alternating focusing from out of focus at infinity to focused and out of focus at minimum focus distance to focused I found a large variation in results eg -7 to +7, -8 to +4, -6 to +10 etc.

I rechecked the Dot-tune method and apparently the above method is not very accurate because it does not take into account mechanical tolerances of the lens.

So could this be the reason for the variable results or does the lens have a fault?

Be sure there are no objects close to the target to avoid false measurements.

By vertical target I think of a target having definite contrasty vertical edges.

Thanks for the advice.  The above test was done in a dark room so the only thing the camera could focus on was the bright computer display.

Today I intend to try again and I will be sure to follow your advice.

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