# Camera/Lens Tests



## Mitica100 (Jan 29, 2005)

*Camera Alignment Test:*



Using masking tape tack a double page newspaper spread with fine print (classifieds or stock market quotes will do nicely) on a wall. Draw a vertical straight line with a black marker in the middle of one page.



Load your camera with any fine or medium grain film. Set it on a tripod, approximately the height of the middle of the newspaper. Place the camera on one side of the paper and at an angle of about 45 degrees, 3 feet from the paper.



Focus on the vertical line, take a picture using available light and at maximum aperture.



Develop. Use a powerful magnifying glass to check the negative. If the black line is sharp and definition falls off in front of it as well as behind it, the camera body is properly aligned. If some other plane is slightly sharper than the line, there is some misalignment of the rangefinder, camera body and lens focusing in Range Finder cameras or camera body, ground glass or mirror in Reflex cameras (SLR). If so, the camera must be realigned by a qualified technician.





*Chromatic Aberration Lens Test:*



Fasten a piece of newspaper to a wall using masking tape. Use a page with fine print, such as Classifieds or Stock Market Quotes.



Photograph it through a blue filter after focusing carefully on the fine print. Take note of each exposures aperture.



Re-photograph the same subject with a yellow or yellow-green filter. Develop and print. If both shots are equally sharp, the lens can be rated sufficiently free from chromatic aberration.







*Internal Lens Finish Test:*



Hold the lens over a true black surface such as a piece of black velvet on which no light is falling.



Aim a strong side light at the lens itself. If the finish and polish of the lens is perfect, the lens should appear black when you look through it. If imperfectly finished surfaces are causing light scattering, the lens will appear gray instead of black.



...more to follow...


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