77mm focusing issues

keos · 01-15-2020, 09:05 PM

Originally posted by stevebrot

Are you using FocusTune along with the LensAlign? I use a different method,* but LensAlign + FocusTune would be my first choice of the commercial offerings, primarily because the software evaluates scatter before suggesting an adjustment.

FWIW, the manufacturer suggests a range of 1.9m - 3.8m target distance, using the distance tool at LensAlign.

As for your hit ratio, it will improve as you back away from evaluating at 100% and reading distance. After all, the classic DOF calculations are based on an 8"x10" print viewed at 12". As for the target not being "still", if you are shooting hand-held, neither is the photographer. The combination of distance shifts works against a quantitative approach to excellence.

BTW...MFA is Canon-speak. In Pentaxland, we talk about AF fine adjustment.

Steve

* Flat resolution target, natural light (north-facing window), 10X focal length, 20 repetitions, center AF point, recording the direction to correct in 100% live view. If about half correct near and about half correct far, no fine adjustment is needed. A bias one way or the other signals a try at improving by adjusting one step at a time. Once the distribution evens out, I field test using the center AF point, knowing that the other AF points will use the same correction factor, even though a calibration of the optical field using the f/5.6 sensor at that point may indicate a different correction. This possibility I choose to ignore.

yes focustune+lensalign, I moved in closer at 3m, but get about the same results. Agree on the movement from both subject and photographer, that's why I count the inside results more, since it is a still target.

I would agree that looking at further distance on print size would make many more shots in focus; unfortunately the way I send files to others is often digital, and even a 2x2 downscale (6mp) isn't enough to salvage unless the focus is pretty perfect. it's hard to explain to a layperson who could be getting results from colleagues with MILC bodies with pinpoint focus with much better hitrates.

MFA not sure is manufacturer specific, at least I don't think. Canon world would be AFMA.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Possible focusing issues with k-3?	Murfy	Pentax K-3 & K-3 II	11	10-21-2019 07:50 PM
Pentax 24-70 Focusing Issues?	danperezphotography	Troubleshooting and Beginner Help	5	02-25-2019 10:51 AM
K5II Focusing Issues after Rain	WooKstah	Troubleshooting and Beginner Help	17	06-13-2018 01:09 PM
For Sale - Sold: Accessories for DA*16-50: Pouch, 77mm hood- ph-rbj 77mm, s100-140	ChatMechant	Sold Items	3	03-19-2018 09:08 AM
Manual Lens focusing issues (focusing screen)	Akarak	Troubleshooting and Beginner Help	15	01-25-2013 06:56 PM

01-15-2020, 09:05 PM	#16
keos Senior Member Join Date: Jan 2018 Posts: 108 Original Poster	Originally posted by stevebrot Are you using FocusTune along with the LensAlign? I use a different method,* but LensAlign + FocusTune would be my first choice of the commercial offerings, primarily because the software evaluates scatter before suggesting an adjustment. FWIW, the manufacturer suggests a range of 1.9m - 3.8m target distance, using the distance tool at LensAlign. As for your hit ratio, it will improve as you back away from evaluating at 100% and reading distance. After all, the classic DOF calculations are based on an 8"x10" print viewed at 12". As for the target not being "still", if you are shooting hand-held, neither is the photographer. The combination of distance shifts works against a quantitative approach to excellence. BTW...MFA is Canon-speak. In Pentaxland, we talk about AF fine adjustment. Steve * Flat resolution target, natural light (north-facing window), 10X focal length, 20 repetitions, center AF point, recording the direction to correct in 100% live view. If about half correct near and about half correct far, no fine adjustment is needed. A bias one way or the other signals a try at improving by adjusting one step at a time. Once the distribution evens out, I field test using the center AF point, knowing that the other AF points will use the same correction factor, even though a calibration of the optical field using the f/5.6 sensor at that point may indicate a different correction. This possibility I choose to ignore. yes focustune+lensalign, I moved in closer at 3m, but get about the same results. Agree on the movement from both subject and photographer, that's why I count the inside results more, since it is a still target. I would agree that looking at further distance on print size would make many more shots in focus; unfortunately the way I send files to others is often digital, and even a 2x2 downscale (6mp) isn't enough to salvage unless the focus is pretty perfect. it's hard to explain to a layperson who could be getting results from colleagues with MILC bodies with pinpoint focus with much better hitrates. MFA not sure is manufacturer specific, at least I don't think. Canon world would be AFMA.