Adjusting focus mask in C1Pro6x

[kit laughlin]

I have worked my way through all of the Lum-Landscape C1Pro tutorials (they refer to C1Pro5, but according to MR, sufficiently similar).

In one of the tutorials, Walter Borchenko states that the focus mask (what a brilliant tool) is set up for Phase backs without AA filters—and that DSLRs that do have AA filters will need the focus mask adjusting, and that the default settings will not necessarily show the in-focus plane. This has been my experience, but a small doubt remains, because the Sony does not have Live View, and thus I can't check this like I could with the Nikons.

Q.1: has anyone here heard of this, and

Q.2: how might one do this?

The only controls that I can see in that tool is the thresholds—can anyone explain how this works, and how one might set the focus mask for a camera like the Sony A850? TIA, KL

 

[dougpeterson]

I have worked my way through all of the Lum-Landscape C1Pro tutorials (they refer to C1Pro5, but according to MR, sufficiently similar).

In one of the tutorials, Walter Borchenko states that the focus mask (what a brilliant tool) is set up for Phase backs without AA filters—and that DSLRs that do have AA filters will need the focus mask adjusting, and that the default settings will not necessarily show the in-focus plane. This has been my experience, but a small doubt remains, because the Sony does not have Live View, and thus I can't check this like I could with the Nikons.

Q.1: has anyone here heard of this, and

Q.2: how might one do this?

The only controls that I can see in that tool is the thresholds—can anyone explain how this works, and how one might set the focus mask for a camera like the Sony A850? TIA, KL

Correct, threshold is the adjustment which he references.

A Schneider XL at f/11 with a digital back would be best used at near maximum threshold, meaning the computer will only indicate something is in focus if it is a very high amount of micro-contrast/detail.

A Canon with a 50mm/1.2 at f/2 would be better evaluated with a threshold set to near minimum, because even where the image is in focus it is only moderately sharp.

The easiest answer is to find an image shot with your most common lens/aperture/body/technique which you find to be acceptably sharp (somewhere in the image) and then adjust the threshold until it agrees with your subjective (and time consuming) evaluation. After that it should serve as a pretty good substitute for checking focus on every single shot in a big folder, and as a good "warning" sign to flag an image for further manual-zooming-in-and-checking-focus investigation.

Doug Peterson (e-mail Me)
__________________

Head of Technical Services, Capture Integration
Phase One Partner of the Year
Leaf, Leica, Cambo, Arca Swiss, Canon, Apple, Profoto, Broncolor, Eizo & More

National: 877.217.9870 *| *Cell: 740.707.2183
Newsletter | RSS Feed
Buy Capture One 6 at 10% off

 

[kit laughlin]

Doug: thank you—a model of precision and lucidity. I will do just as you suggest, using the excellent 100/2.8 macro and the Sony 135/1.8. I will report back. Cheers, Kit