Canon lenses calibration

Started 6 months ago | Discussions thread
OP CESA Regular Member • Posts: 477
Re: Canon lenses calibration

Gridlock347 wrote:

I've had FoCal for a few years, but since never had any focusing issues, and after reading instructions, it seemed too tedious for me. Then I got a 5DsR and the 50 1.2 L, and started thinking about testing this combo with FoCal. Still haven't gotten around to it, but I was wondering:

Why not simply set up camera on tripod, etc., then take one photo with Live View using the sensor to directly focus the image at max aperture. A $1,000 bill would make a good, detailed subject. Then, take another photo with the mirror down, which will determine focus via the mirror/focusing screen. Then compare the two images. If they are identically sharp, then the mirror-down focusing system is working properly. If the images' sharpness is noticeably different between the two, then an MFA tweek may be needed.

I am assuming that the Live View image would be the best possible sharpness since there is no mirror, etc. between the lens and the sensor that could get out of adjustment.

Any reason this wouldn't work?

Depends on what lens you are calibrating I guess. It would be interesting to see what results do you get after calibrating.

That's indeed another method in which Dustin Abbott suggests in one of his tutorials. I didn't do it like that but the problem here that I am facing with FoCal is that at the recommended distance I get +5. At the minimum working distance I get +18. An in between I get around+10.

Problem is, which distance do you use? If I was shooting say at the minimum distance of 3m, then calibrating the lens at 3.7m wouldn't be an issue and wouldn't see any problem in million years and that's is probably what people in here are saying when they refer that don't see any problems. The question I would have for them is: Do you calibrate at the recommended distance and have you shot at the minimum distance?

This prissily what I am facing. With AFMA setting at 0, at all distances from minimum working to 3.7m (recommended) images are soft. When I calibrate at recommended distance when I go and take pictures at the minimum working distance 1.2m to 1.5m the images are soft. When I calibrate the lens at 2m the images are good and ok going to 1.5m. With that same setting at 3.7 images are all right. Of course at 3.7m I am not getting the full potential of the lens because FoCal says it is +5. But +5 at 1.2m images are not really sharp/focused 100% so not taking full potential of the lens.

At 2m which is the sort of middle ground I get +9 and that reveals to be an ok compromise but never will take the lens full potential at the minimum wokring distance neither at recommended testing distance which is more or less the limit for full body type of shot.

I don't know if this is a problem with the AF of my 6D, which I got used from an used shop with 1 year warranty. Maybe it is the nature of the lens.

Calibrating at 2m and using it at 1.2m the images are not at full potential but are ok now going to 3.7m and shoot at that distance with the AFMA setting from the 2m calibration probalby shouldn't be a problem as well. That one haven't tried yet - shooting at 3.7m with the 2m calibration value.

It would be interesting to see what you get with your 50mm f/1.2 which I plan to get as well at some point in time.

Using live view, although slow, it is bang on.

If I have the time will try to do that, manually calibrate the lent even if I have to go one AFMA step at the time (from 0 to +20 since the lens isn't back focusing) at 3 distances. Curious to see if the results will be the same as FoCal. But for now will have to go with what focal is telling me.

BTW, at 1m to 1.5m the ideal AFMA value is +18. Images are tack sharp. Eyelashes don't lie. But I guess all this thing with the mirror used for AF is all ambiguous and it shows their flaws at big aprtures: f/1, f/1.2 and f/1.4. That's is why mirrorless are the future although it will take some time for Canon RF glass price get to the current EF price point.

Using live view probably hould suffice in cameras like the 6DMK2 in which the screen is fully articulated with face detection where shots with this lens are tack sharp or any other like the 5DMK3 and MK4.

Cheers

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