Open Photography Forums  
HOME FORUMS NEWS FAQ SEARCH

Go Back   Open Photography Forums > OPF Welcome Hall > Breaking News

Breaking News Updates, innovations, equipment: moderated!

Reply
 
Thread Tools Display Modes
  #31  
Old December 16th, 2008, 02:58 PM
Asher Kelman Asher Kelman is online now
OPF Owner/Editor-in-Chief
 
Join Date: Apr 2006
Posts: 32,717
Default

Quote:
Originally Posted by Doug_Kerr View Post
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/iss...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
__________________
Follow us on Twitter at @opfweb

Our purpose is getting to an impressive photograph. So we encourage browsing and then feedback. Consider a link to your galleries annotated, C&C welcomed. Images posted within OPF are assumed to be for Comment & Critique, unless otherwise designated.
Reply With Quote
  #32  
Old December 16th, 2008, 03:23 PM
Doug Kerr Doug Kerr is offline
Senior Member
 
Join Date: May 2006
Location: Alamogordo, New Mexico, USA
Posts: 8,194
Default

Hi, Asher,

Quote:
Originally Posted by Asher Kelman View Post
Doug,

This is exactly what the LensAlign™ does!
Indeed (as I mentioned the first day this device was mentioned here).

Best regards,

Doug
Reply With Quote
  #33  
Old December 16th, 2008, 03:44 PM
Asher Kelman Asher Kelman is online now
OPF Owner/Editor-in-Chief
 
Join Date: Apr 2006
Posts: 32,717
Default

Hi, Asher,

Quote:
Originally Posted by Asher Kelman View Post
Doug,

This is exactly what the LensAlign™ does!
Quote:
Originally Posted by Doug_Kerr View Post
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
__________________
Follow us on Twitter at @opfweb

Our purpose is getting to an impressive photograph. So we encourage browsing and then feedback. Consider a link to your galleries annotated, C&C welcomed. Images posted within OPF are assumed to be for Comment & Critique, unless otherwise designated.
Reply With Quote
  #34  
Old March 20th, 2009, 05:55 PM
Ron Morse Ron Morse is offline
Senior Member
 
Join Date: Sep 2006
Location: Maine
Posts: 753
Default

So Asher, what are your findings after using the LA?
__________________
Somehow the more that I learn, the less I find that I know.

Ron
Reply With Quote
  #35  
Old March 25th, 2009, 07:51 AM
James Newman James Newman is offline
Senior Member
 
Join Date: Apr 2007
Location: Somewhere in the Midwest
Posts: 658
Default

Yes Asher...it has been quite sometime now so what were your results using the LensAlign?
James Newman
__________________
James Newman
Chicagoland
www.pbase.com/jnewmanco1 c&c welcomed
Reply With Quote
  #36  
Old March 25th, 2009, 10:45 AM
Asher Kelman Asher Kelman is online now
OPF Owner/Editor-in-Chief
 
Join Date: Apr 2006
Posts: 32,717
Default

Quote:
Originally Posted by James Newman View Post
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
__________________
Follow us on Twitter at @opfweb

Our purpose is getting to an impressive photograph. So we encourage browsing and then feedback. Consider a link to your galleries annotated, C&C welcomed. Images posted within OPF are assumed to be for Comment & Critique, unless otherwise designated.
Reply With Quote
Reply

Bookmarks

Tags
back focus, front focus, lens adjustment, lensalign™, live view

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -7. The time now is 12:12 PM.


Posting images or text grants license to OPF, yet © of such remain with its creator. Still, all assembled discussion © 2006-2017 Asher Kelman (all rights reserved) Posts with new theme or unusual image might be moved/copied to a new thread!