BirdForum is the net's largest birding community dedicated to wild birds and birding, and is absolutely FREE!

Register for an account to take part in lively discussions in the forum, post your pictures in the gallery and more.

Reply to thread

Message: <blockquote data-quote="birdeast" data-source="post: 1840913" data-attributes="member: 25124">just read an article that someone linked over on dpreview (cant remember thread so havent found the link again  <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite3" alt=":(" title="Frown    :(" loading="lazy" data-shortname=":(" />  ).  I believe the article was written by one of the lens rental outfits in the US.  According to them, they spend (waste) a lot of money on returns for people claiming lens front focus, back focus, etc.  According to them, they test everything and only find a very small percentage of legitimately bad lens.The explanation they give for the number of returns comes down to cameras and lens and the amount they are out of 'sync'.  They gave example of a camera maybe being +3 away from "perfect".  This is ok if you get a lens that its -3 away from perfect.  The problem occurs when someone with a +3 problem camera gets a +3 problem lens...  now you have a +6 issue that leads to a back focus / front focus scenario.  The +3 / -3 is just an arbitrary scale used by author to make a point.The way this issue was overcome by pro's back before cameras had the ability to be calibrated for individual lens was for the pro to send all of their lenses and camera bodies to Nikon or Canon to have them "sync'd".  The author summarizes that with so many camera bodies being able to calibrate lenses now, it doesnt make sense to keep changing what are perfectly good lens until you find one that matches the idiosyncrasies of your particular camera.If i can find the article.... i will link it.  I recently checked out my 500mm f4 on my d300 and found it to be perfect.  My Sigma 100-300 however required some adjustment.  This is a valuable feature that I will want on any body I purchase going forward.</blockquote>

Verification