Micro Focus

As I do not have a body with Micro Focus Adjustment, I don't know how it works.

As I understand it, I could attach each of my lenses (Canon or not), and calibrate each, probably differently due to their varying characteristics, for use with a body with this feature, and have them focus more accurately after the procedure.

Is this correct?

Can someone who has done this procedure comment on how it is done (and how easily it is done, too!)?

Which Canon bodies have this feature? I think it would be a very good reason to upgrade ....

Maxdave

Maxdave wrote in post #6363531
As I do not have a body with Micro Focus Adjustment, I don't know how it works.

As I understand it, I could attach each of my lenses (Canon or not), and calibrate each, probably differently due to their varying characteristics, for use with a body with this feature, and have them focus more accurately after the procedure.

Is this correct?

Can someone who has done this procedure comment on how it is done (and how easily it is done, too!)?

Which Canon bodies have this feature? I think it would be a very good reason to upgrade ....

Maxdave

The camera can be set overall to a microfocus +/- amount, and then a number of lenses can each be individually set to a +/- amount. Caveats: if you have a duplicate (or near duplicate) of a lens (say a 70-200 f/2.8 and a 70-200 f/2.8 IS) the body cannot differentiate between those two lenses, and only one correction factor can be stored.

Currently, both Mark III cameras have it, and it is slated for the 5d2 and the 50d.

A good article on one method of microfocus adjustment.
http://www.northlight-images.co.uk …s3_af_micoadjus​tment.html

You might want to check out
http://www.northlight-images.co.uk …s3_af_micoadjus​tment.html
[Edit]Doh, just spotted that fxk already posted the link.

charlesking wrote in post #6363825
You might want to check out
http://www.northlight-images.co.uk …s3_af_micoadjus​tment.html
[Edit]Doh, just spotted that fxk already posted the link.

Better twice than never!
Proves great minds run in the same circles!

Thanks for the link. I've never heard of using the moire pattern on your monitor. Interesting.
So this may be a silly question, but...
If a lens is "off", is it always off consistently at all focus distances? That is to say, if it front focusses at 3 meters, is it possible for it to somehow back focus at 10 meters?
I guess i should ask a similar question for zoom lenses > if a lens is "off", is it off the same way throughout the focal length of the zoom range (ie same at 24mm and 105mm)?
Just thinking if front/back focus isn't consistent, it may be possible to adjust focus to get it bang on at a given distance (or FL in a zoom), but unknowingly make it worse at others.
I've never used this function (never had a body that had it... yet ), so sorry for the naive question.
Greg

BiPolarBear wrote in post #6364339
Thanks for the link. I've never heard of using the moire pattern on your monitor. Interesting.
So this may be a silly question, but...
If a lens is "off", is it always off consistently at all focus distances? That is to say, if it front focusses at 3 meters, is it possible for it to somehow back focus at 10 meters?
I guess i should ask a similar question for zoom lenses > if a lens is "off", is it off the same way throughout the focal length of the zoom range (ie same at 24mm and 105mm)?
Just thinking if front/back focus isn't consistent, it may be possible to adjust focus to get it bang on at a given distance (or FL in a zoom), but unknowingly make it worse at others.
I've never used this function (never had a body that had it... yet ), so sorry for the naive question.
Greg

The question is not naive. As I also do not have that camera, I, too, am making assumptions.

My Logic would have it so that if it is on at one focus distance it is on for the range. Same with Zooms. My Logic would have it that Canon designed the systems in that way.

My guess is that anything is possible. I would assume that if micro-focus does not "fix" the lens over the entire focus range or over the entire zoom range, I'd guess the lens is operating outside Canon's design spec, and needs to go back to Mother Canon for some love and understanding.

BiPolarBear wrote in post #6364339
If a lens is "off", is it always off consistently at all focus distances? That is to say, if it front focusses at 3 meters, is it possible for it to somehow back focus at 10 meters?
I guess i should ask a similar question for zoom lenses > if a lens is "off", is it off the same way throughout the focal length of the zoom range (ie same at 24mm and 105mm)?
Just thinking if front/back focus isn't consistent, it may be possible to adjust focus to get it bang on at a given distance (or FL in a zoom), but unknowingly make it worse at others.

This seems to be more of an issue for zoom lenses, I've read several reports of people who've found they need different adjustments for different focal lengths. Since modern zoom lenses are almost all really varifocal that's not surprising, and it suggests a fault with the alignment of the optics.

Since all these systems are proprietary, no-one's released any detailed info about what AF adjustment actually does, but it seems reasonable to assume that it alters the calibration of the focus motor. If the elements aren't moving correctly as the focal length is changed then the focal plane will be moving back-and-forth in a way that can't be fixed in this manner. If you get this problem, the lens needs to be fixed.

A couple more links if you're interested:
http://www.focustestch​art.com/chart.html
http://www.zimbio.com …st+chart+help+P​entax+K20D
(the principles are the same for all cameras)

The second link and chart are very useful, thanks.