d800 focus testing with different targets

Started May 15, 2013 | Discussions thread
Per Baekgaard Senior Member • Posts: 1,268
Re: d800 focus testing with different targets

Julian Vrieslander wrote:

My results from the DotTune method were also somewhat variable [...]  When I stepped through the tune settings, the results were often different, depending on the direction I was going (up or down on the scale).

I've found that when you change the tune value, there is some hysteresis in whether the dot is flickering or not. So if it showed OK on the previous it takes a litlle longer for it to show not-OK on the next value whereas a previous not-OK value seems to result in a faster not-OK value on the next.

I've done the test on multiple lenses and over several days with the same lenses, and have repeatability to within 1 step-value for the range (i.e. it is often 22 step-values for me at the tested range). The actual "best focus" can vary a little, depending on how well you get that established, but the range remeains the same for the same lens and conditions. But the trick is to wait long enough for the "corner" values to really show that they are OK and then step a little up and down around those values to ensure they are consistent. Only values that are always OK should of course be accepted as a possible end-of-range value.


 Per Baekgaard's gear list:Per Baekgaard's gear list
Nikon D800 Nikon D500 Nikon AF-S Nikkor 70-200mm f/2.8G ED VR Nikon AF-S Nikkor 14-24mm f/2.8G ED Nikon AF-S Nikkor 24-70mm f/2.8G ED +17 more
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