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  • Welcome to the new site. Here's a thread about the update where you can post your feedback, ask questions or spot those nasty bugs!

News: LensAlign™ Seen! Announcement coming soon!

Asher Kelman

OPF Owner/Editor-in-Chief
Regarding the matter of using just an angled test target for AF testing, I happened to run into this from Chuck Westfall of Canon in his Tech Tips column in The Digital Journalist for December 2008:

• Do not attempt to autofocus on an angled chart, because doing so will degrade the consistency of the camera's focusing measurement. Keep in mind that the camera's AF sensor is comprised of multiple pairs of linear pixel arrays. If you attempt to autofocus on a single line in an angled focusing chart, only a few pixels from each active pixel array will "see" the target. Ideally, the contrast in the reference target should cover the entire area of the camera's center focusing point, and the reference target should be perfectly parallel to the camera's focal plane.

This is consistent with Canon recommendations I had seen in the past.

Here is the link to Chuck's column:

http://www.digitaljournalist.org/issue0812/tech-tips.html



Best regards,

Doug
Doug,

This is exactly what the LensAlign™ does! The left part is the orthogonal target, obeying Canon's directive. The right part with the slanted ruler is what we look at in the photograph taken after focusing on the orthogonal target.

The latter action gives us the line of sharpest focus!

Asher
 

Asher Kelman

OPF Owner/Editor-in-Chief
Hi, Asher,

Doug,

This is exactly what the LensAlign™ does!
Hi, Asher,

Indeed (as I mentioned the first day this device was mentioned here).

Best regards,

Doug
I know you knew. :)

I Just wanted to underline that as a Canon rep in a Camera store was wondering about that very point! I just wanted to emphasize that the focus is not on sloped rule but on the orthogonal (Siemens-like, star), black and white radial focus target!

As always your explanations are always valuable, in fact we depend on them!

Asher
 

Asher Kelman

OPF Owner/Editor-in-Chief
Yes Asher...it has been quite sometime now so what were your results using the LensAlign?
James Newman
I have sent you a PM. No further report anytime soon. Good report in Luminous Landscape here.

I've delayed my purchase of new cameras for this as I have to focus on other gear and work.

Asher
 
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