If you were doing lens testing using a full frame DSLR, you'd put the targets at the center and corners of a 24" x 36" rectangle to get the same magnification ratio. For APS-C sensor cameras I usually place them on a 15"x22" background and if that fills the frame, the magnification of the system will be around 1:25 which for a number of reasons is a good number to show the typical performance of a lens. Now a 4圆 target isn't very big, so the idea is to print a number of them and place them in the center and at the corners of a larger chart. The lens testing chart I'm going to use can be printed on 4圆 card. If you want something to do lens testing that's a little quicker and easier (and much cheaper) then you can do some simpler tests using a test chart as described below. It can give you a lot of technical information on an lens (if you do the tests right) and it's an excellent package, but even the "lite" version is pretty complex and more than most people want to deal with. I won't go into details of it here since you can find everything you'd ever need to know on their website. It's currently (2013) $299 for the "lite" version and $2200 for the pro version (though a limited free trial edition is available). If you want to go all the way, I'd recommend you look at the Assuming you have a camera and lens in good calibration and you are getting an accurate indication of focus by the AF system, then what?Īt this point you have to decide just how much effort you want to put into measuring the optical characteristics of your lens. To do that you have to do some focus testing as I described in the article HERE. Well, you have to be sure that the lens is focusing properly.
So you have the camera on a tripod, what's next.
If the shutter speed is high enough and your hands are steady enough, you may get a critically sharp image, but don't bet on it happening every time.
Photographers don't realize that hand holding a camera (even if it or the lens has image stabilization), isn't the way to get the maximum possible sharpness. Well, unless you're shooting a static subject with the camera and lens on a tripod, it probably doesn't mean much. Probably the most frequent complaint or cause for concern about a lens is that it's not sharp, but what does that mean? Part 6 - Lens Testing for Resolution, Chromatic Aberration and Distortion
0 kommentar(er)
