|Posted: Thu Jan 18, 2018 11:00 pm Post subject: Identifying front- or back-focus: An excellent target
|I thought I'd post this due to my recent trials with such an issue.
As with most instructions, print the target, lay it flat and light it well,
place camera at 45-degree angle, take shot(s), view, adjust.
This works very well, and objects can easily replace a printed target.
But one point which always escaped me for some reason was,
"How are the adjustments for either situation dealt with?"
This sums it up very succinctly:
|If you focus the subject in the viewfinder to be sharp, but the image is focused closer to the foreground, this is FRONT focus. To correct this you need to fit a THINNER shim in place in between the prism and the focus screen.
If you focus the subject in the viewfinder to be sharp, but the image is focused further to the backround, this is BACK focus. To correct this you need to fit a THICKER shim in place in between the prism and the focus screen.
This got me on a clearer understanding of the process, as opposed to the sometimes
confusing or contradictory information I had found in the past.
I like the chart because it's much more than a graded scale of lines.
It's available with various tones of the greyscale, includes character fonts.
There's actually more to see with this one, unlike the many others which
appear to be nothing more than a ruler on paper.
Well-written detail of the process and the charts can be found here:
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