I would like to do a lines-per-millimeter resolution test for my lenses (45,55,100,200). Does anybody here have some experience with it and would be able to give me some recommendations ? What is necessary for this test, will it work for rear convertor (which I am hoping to buy soon) used on 200/4 lense also ? Thank you for your help. Pavel.

-- Pavel Medek (pavel@talema.cz), April 30, 2000

Answers

I believe that Edmund Scientific in New Jersey, USA has test targets that fit what you are looking for. It is critical to use the heaviest tripod you can find for doing this test and don't have the legs extended when you shoot. SR

-- Steve Rasmussen (srasmuss@flash.net), May 08, 2000.

What about using strobe to eliminate shutter shake?

Is there a documented procedure how to execute this test; i.e standard magnifications, etc?

-- Bruce Gavin (doc@compudox.com), July 04, 2000.

Most test targets either have a stated multiple of the focal length or can be read and converted to lp/mm knowing the focal length and distance. The test target I use is only usable to 72 lp/mm and 40x the focal lenght, so I use it mostly to sort out the dogs.

The exposure should be in a darkend room, after focusing with bright lights, by opening the shutter and keeping it open for several seconds and then exposing with a flash unit. This method if done correctly, will eliminate all other factors and let you read just the lens resolution. Kornelias at Ziess says this how they test their lenses.

As a follow up, I also do daylight testing using a heavy tripod and 1/1000 to see if the field results correlate with the flash results. For longer lenses this may be the only way to test unless you work at night with a portable light and flash.

-- Gene Crumpler (nikonguy@worldnet.att.net), July 05, 2000.