Q: I have a 10-year-old Nikkormat with a variety of Nikon lenses. I would like to buy another body so I can use two lenses and/or black-and-white and color film at the same time.

Since my wife also needs a camera, I want one we can share. We'd like one that will accept my Nikon lenses but also give her the automatic control she wants. The new Nikon EM is lightweight, inexpensive, small and automatic, but I find that my old lenses will not synch to the automatic.

The FE is larger and heavier than my wife likes and more money than I want to pay. Is there a solution to our situation?

A: Yes, and quite an easy solution at that. Most older Nikon lenses can be adapted to any of the Nikon models, but there's a catch. It depends on the serial number of the lens. The 10-year time may also give you trouble, since some of the lenses of that vintage and before cannot be adapted.

To find out which of your lenses can be altered, take the serial number to a Nikon dealer who has a list of lenses that will take a new coupling.

If your dealer can't help you, contact Nikon or one of its authorized repair services -- your dealer can give you the address of the one nearest you.

The approximate cost for these conversions is $18.50 for a standard lens such as a 50-, 100-, or 200-mm, and $33.50 for zooms.

Q: Can you explain why one 35-mm slide should be washed out and the next perfect when taken of the same scene from the same position with identical lighting? The camera is a Zeiss Contaflex, 15 years old.

A: Quite likely the erratic behavior is caused by oil gumming up on the iris blades of the lens. This can be corrected by having the lens cleaned at an authorized Zeiss Service Center, such as ZV Service Corporation, 356 West Merrick Road, Valley Stream, Maryland 11580.