The Canon EOS and Photography Forums

Bob:
I just bought my new Sigma 150-500 and so far seems to be pretty good.

Do you have any tips for evaluating sharpness on screen?  I know your lens evaluation article says "don't do that", but...

Are most of your sample shots (especially of the Sigma 50-500) taken with a tripod or handheld?

Unless I'm testing stabilization systems, most of my lens review shots are taken using a tripod. A tripod is the only way of being certain that camera movement isn't affecting sharpness.

Maybe the easierst way to test sharpness is to compare images with a lens you know to be really sharp, for example a 50/1.8 or an 85/1.8 stopped down to f4 or 5.6. With a long lens you have to back away from your target of course but if you have a flat target and fill the same amount of the frame with it using each lens (or each different focal length for a zoom), you can get a good idea of relative sharpness.

Thanks, do you have any procedure for evaluating the sharpness on your monitor? 

Just the eyeball test. If it looks sharper it is sharper. The best target is one that has fine detail down to a level that isn't resolved.

However if a 100% blowup of a digital image looks sharp, it is sharp. It's generally not hard to spot a soft image.

I presume you've seen this article - http://www.bobatkins.com/photography/technical/lens_sharpness.html

and these examples http://www.bobatkins.com/photography/technical/lens_test_samples.html

Yes, I have, thanks, I even have the peg board ready to go.  Unfortunately, I just moved to Albuquerque, so I do not have that many overcast days to play with.  It was nice in Southern California, you could count on many overcast mornings!

Now I just need a new tripod, I have a lightweight travelling one that is not going to work at all with the 150-500!