ballsafire Loc: Lafayette, Louisiana

This is about a Canon 28-105mm F/3.5-4.5 USM EF Lens. In a review of this lens I quote-- "Stopping down even 1/3 of a stop improves image sharpness noticeably-until the long end of the focal length range where 70mm focal length range are sharp and at f/8, images are even sharper right to the corners. At 70mm, corners are not as bad at f/8, but at 105mm, even 1.6x corners are quite soft. If you consider this a 28-70mm f/4.0-4.5 lens you will be happier." end of quote.
Certainly I understand that the lens is not so hot outside 70mm but I don't understand what is meant by "Stopping down even 1/3 of a stop--" -- what is he doing? I am still learning photography - Could someone clearify this jargon for me? Thanks!! P.S. I have an EOS Rebel T1i camera.

imagemeister Loc: mid east Florida

He is just saying best to stop down 1/3 to 1/2 stop from wide open to get much improved image quality - but this could be said for ALL lenses !

cosmo54 Loc: Easton, PA but will travel for photos

and in case you didn't know...."stopping down" means changing the f stop to a higher number...that is, smaller aperature. sounds backwards, but its true.

oldtool2 Loc: South Jersey

Can you tell us who, or where, you found this review? For one, I do not agree with him/her.

What they are saying is the corners of the photos are always soft. On my copy of this lens I don’t find this to be true. As for the comment about “stopping down” all lenses have what is considered a sweet spot. This is normally about two stops from being wide open. Wide open on this lens is F/3.5-4.5 depending on what zoom you are using. At 28mm it is f3.5, at 105mm it is f4.5. It is generally considered that f8 to f10 will put you in the sweet spot, where the lens is going to be the sharpest. This is not always true and can vary from lens to lens. The only way to be sure is to test the individual lens with a program such as FoCal.

This can, will, also change depending on whether you are using a crop sensor or a full frame camera.

As for the statement “what is meant by "Stopping down even 1/3 of a stop--" what is he doing? He is trying to find the sweet spot,the sharpest spot, by adjusting the aperture, or as you may know it by, the f-stop. On many cameras you can pick in the menu how much the f-stop moves with each click, 1/3, ½ or a full stop each time you change it.

I hope this helps you understand a little. If you are not familar with camera jargon a statement like that can be confusing.

Jim D

imagemeister Loc: mid east Florida

If you are considering this lens, you might want to look at the Tamron SP 28-105 F2.8 - about $300 on eBay or $400 at KEH. It is a great lens...