How to compare lenses

[jim c]

Just purchased a Tamron 28-75 and will take some shots tomorrow comparing it to the 18-55 kit lens. I also can compare it to my 50 1.8 as well. Any suggestions are welcome...I will post them tomorrow. One thing...I can't spend a whole day doing the test. The simpler, the better. Thanks....

[cmM]

identical setting
-same position (tripod)
-same focal length
-same settings (manual focus, manual exposure, same WB setting)

[ron chappel]

Use a tripod

TAKE ALL SHOTS AT THE SAME MAGNIFICATION!!!!!!!!!!! THAT WAY THE IMAGES FROM 18mm AND 55mm (or whatever) CAN BE COMPARED DIRECTLY -this is a great bonus to everyone becasuse we can see the relative image quality at different focal lengths

Make sure the lighting conditions remain the same (no variable cloud cover)

Compare the 18-55 wide open with the tamron at that same aperture (f5.6 or whatever it is)
-But also take some shots at larger apertures/wide open with the tamron so we can see where the quality level drops off
TAKE SEVERAL SHOTS AT EACH SETTING AND CHOOSE THE BEST TO ELEMINATE FOCUS ERRORS-focus is critical when working at the limits of a lens' resolution
(it's normal to test lenses by focussing on a flat plane object that has writing on it or detail of some sort but try to add something just behind and just in front of the plane of focus near the middle of the frame so you can see just how accurate the focus is.Not critical at all but handy)