I don’t think I need to say anything about tripods, but I’ll go into a bit more detail on the other two requirements. Of course, they’re blurry when slightly out of focus, but the way that they blur can be quite revealing. You Can Learn a Lot About a Lens by Observing it Slightly Out of Focus Those that do fail in the center always also fail off center. Eight out of every 10 lenses we fail as ‘optically decentered’ would pass fine if center resolution was the only thing we checked. Most lenses can be pretty badly decentered before center sharpness is affected very much. Center Sharpness is the Least Sensitive Test of a Lens If you are tilted at a slight angle to the chart, you’ll get a lot of the same results you would get if the lens were decentered. This is the main reason a tripod is needed, although not the only reason.

Being Perfectly Square to the Test Chart is Required After that you can try it hand-held if you like, although you will lose accuracy. So I recommend testing your first 9,000 lenses on a tripod. It usually takes about 6 months of testing 75 lenses a day before they can, though. Some of my most experienced techs can test hand held. A Few Things Before We Start You will need a tripod. Testing is a lot faster than trying out 4 copies before you decide a lens just isn’t for you. But that’s not always convenient or possible. You can just take pictures and if you don’t like the lens send it back. Nobody needs to do optical testing, of course. It can be helpful to know if the problem is with the optics of that copy, rather than the focus system, technique, or simply that the lens isn’t designed to perform any better than that. For that you do need Imatest, a bench, or just a lot of photographs.īut if you have a lens that isn’t performing like you think it should this will let you determine if the lens is optically aligned and centered properly. It’s doesn’t let you compare two different lens models and decide which is sharper. This is not going to let you test 6 copies of a lens and determine which is the absolute sharpest copy on your camera. But let me be clear about this is not, so I don’t waste your time if you wanted something else.

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