A "good copy"

[boomerang]

I see this refrenced a bit about a new lens. How do you know if you have a good copy. I shoot now mainly with the 50mm 1.4 and am really happy with the pictures.I just looked at a new post with this lens and the pics were really sharp and had pop to them. I say that in most cases I have a few really sharp shots with pop and the rest are soft. It may be im new to the camera world and shooting-or I just need to know my "copy" is up to par. I do ten to stand close to my subject, what is the focal length suggestion on this lens?

thanks

[tim]

You could do a focus test like this one (http://www.mrwild.co.nz/ExperimentalGallery/Tests/FocusTests/Set2/index.html) to see if the lens is focusing correctly, my 1.4 isn't, my other lenses are. Tests need to be done on a tripod, in a well lit room, focusing on an object parallel to the sensor, mirror lockup and cable release if possible, or timer's fine. Once you work out the lens is focusing correctly it's most likely user experience to cause problems. You'll need to use some kind of sharpening to make the pictures look really sharp.

[boomerang]

Thank you Tim thats what I thought, I think right now its more tecnique than hardware that is the problem.

[ron chappel]

Besides what Tim mentions you can add to that by testing side to side (or up /down) sharpness consistancy.Some lenses can exibit softness at one edge.

Other than that you really have to compare your lens to another example.Obvious dud lenses can be found out simply by posting nice big images on this forum and asking other owners what they think.
But if your lens is obviously ok then a side by side comparison is needed
-if you can be bothered-i suspect not as you say the pics look really sharp and have pop to them...a sure sign that there are no serious issues.

[ron chappel]

Oh-by the way-
i've been looking for the 'official' canon focus test online but as yet have not found it.However i did find some very interesting info on testing the nikon D70.Sure it's a different brand but the problems (in getting a reliable test result) seem to near identical to the canons.
It discusses some very interesting issues such as focus sensor size and shape plus other things.
http://md.co.za/d70/chart.html

[boomerang]

Thanks for the input and link Ron.