How do you test lens sharpness?

I'm just curious but how do you test if a lens is decently sharp? I just got a 28-135mm IS USM from a friend and it seems great but I just wonder how sharp it is in comparison to my kit lens?

My guess is that the 28-135 is slightly sharper than the kit lens. The 28-135 is a great focal length and you will enjoy it.

Aren't there cards that have markings on them that are used to photograph and then look at sharpness and check DOF? I don't know what they are called but I have seen images in these forums with them.

TMR Design wrote in post #2146960
Aren't there cards that have markings on them that are used to photograph and then look at sharpness and check DOF? I don't know what they are called but I have seen images in these forums with them.

Yeah, where do you get those cards from?
I've seen them here before too.

I don't know. I was going to go hunting on the net to see what they are and if you can some initial testing by printing sometihng out, or a version of those cards.

I read in one of the major photography magazines that uses a specialized optical device along with specialized software that analyzes lenses, which the magazine uses for publishing the comparative results of two similar lenses. They claim to be the only ones who has this set up as it's very expensive. Maybe someone here also read the article last month (Sept or Oct) and can be more specific.

I did a Goggle search for self testing lenses and came up with lots of technical readings.

I just found this. I am not sure if it what we really want but it looks like it might be.

http://www.normankoren​.com/Tutorials/MTF5.ht​ml

I just take some pictures and if I'm just blown away then I know it's sharp...If I'm like um...maybe I made a mistake, then I get out the tripod and shoot a few dozen images in a controlled setting and realized I did make a mistake. I try to remember a monitor kind of skews the print perspective a bit.

wasnt there some sort of cheap battery test as well?

I have been doing some testing on my Sigma 17-70mm f/2.8-4.5 lens just to get an idea of how fast and how sharp it is and so far it is performing very nicely, even in pretty low light. I did some DOF test too and I am pleased with those results.

There's a nice little post (with pictures even) on this very subject in the EF Lens FAQ stickied at the top of this page.

Here's an easy way to test for sharpness. Mount a yardstick with easily readable numbers on it at a 45 degree angle either vertically or horizontally from where you shoot. Use center point focus, focus on the number 18, shoot then view the image on your computer monitor. If #18 is perfectly focused then the lens is sharp. If any other number is in better focus than #18 then the focus is off.

Well, this is exactly how not to test for focus accuracy.
It may tell you about sharpness,. as sharpness does not necesarily require that you get the area in focus sharp, just something,. it's more about lens resolving power etc..

..but again I refer you to the article in the FAQ for the focus accuracy test.

Shooting an object at a 45* angle is a great way to get really nervous about AF accuracy.

Anyway,. my mistake re: the OP's original question. I jumped to the conclusion that you were talking about focus accuracy, and I think I was mistaken there.

Sharpness is a matter of resolving power, and we don't have a lot of easy ways to measure it. As Photocout mentions, this equipment whcih measure MTF etc. is a little out of reach.

Best thing to do is just to shoot and see what you think.

Since I will not be using a lens very often to shoot test patterns or lines of batteries, those tests seem rediculous to me. I prefer the shoot and appreciate method. If I use the lens and appreciate the shots I get then I like the lens and keep it.

rklepper wrote in post #2148305
Since I will not be using a lens very often to shoot test patterns or lines of batteries, those tests seem rediculous to me. I prefer the shoot and appreciate method. If I use the lens and appreciate the shots I get then I like the lens and keep it.

Amen Doc