Go Back   Steve's Digicams Forums > Digital SLR and Interchangeable Lens Cameras > Canon Lenses

Reply
 
Thread Tools Search this Thread
Old Mar 1, 2014, 2:54 AM   #21
NHL
Senior Member
 
NHL's Avatar
 
Join Date: Jun 2002
Location: 39.18776, -77.311353333333
Posts: 11,543
Default

Quote:
Originally Posted by rainrunner View Post
Makeitwide - a few questions about the fix you applied on the lens:
Did this change where the camera focuses when using autofocus?
Did this make any changes to infinity focus @ f/22?
The issue seems to be @ only wide open, which I don't have...
-> This lens is super sharp if the aperture is closed down just one stop (i.e. f/4 or above), no need to go to f/22:


__________________
photos (ϕοτοσ), light
graphos (γραϕος), painting
NHL is offline   Reply With Quote
Old Mar 9, 2014, 4:29 AM   #22
Junior Member
 
Join Date: Feb 2014
Posts: 8
Default

Quote:
Originally Posted by TCav View Post
The Canon T3i is diffraction limited at about f/14, so f/22 would be pretty bad.
Quote:
Originally Posted by rainrunner View Post
Makeitwide - a few questions about the fix you applied on the lens:
Did this change where the camera focuses when using autofocus?
Did this make any changes to infinity focus @ f/22?
yeah, I don't use f/22. For me, above f/11 picture starts to get muddy.

I did not notice any issue with autofocus after the fix.
I tried closeup 1ft away, and infinity. Were both sharp at f/2.8.

I don't know why you would ask about infinity focus at f/22. Is this a known issue?
makeitwide is offline   Reply With Quote
Old Mar 9, 2014, 12:19 PM   #23
Senior Member
 
Join Date: Jan 2014
Location: Hillsboro, Or
Posts: 268
Default

Makeitwide - From what I have read and what I experienced on my own Tokina 11-16, Infinity is sharp until f/11 or so, but then is out of focus again once you get near f/22.
rainrunner is offline   Reply With Quote
Old Mar 9, 2014, 12:55 PM   #24
Senior Member
 
TCav's Avatar
 
Join Date: Sep 2005
Location: Washington, DC, Metro Area, Maryland
Posts: 13,543
Default

Quote:
Originally Posted by rainrunner View Post
Makeitwide - From what I have read and what I experienced on my own Tokina 11-16, Infinity is sharp until f/11 or so, but then is out of focus again once you get near f/22.
Yes, that's the diffraction limit I mentioned, and varies with the resolution of the sensor. (Higher resolution sensors reach their diffraction limit at larger apertures, or numerically smaller f-numbers.)
__________________
  • The lens is the thing.
  • 'Full Frame' is the new 'Medium Format'.
  • "One good test is worth a thousand expert opinions." - Tex Johnston, Boeing 707 test pilot.
TCav is online now   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 1:00 PM.