Q. Would you explain the effect glasses have on focusing?

A. Some people find they have problem focusing, especially with the popular single-lens reflex (SLR) cameras; usually it's because they don't wear glasses and should.

Most SLRs have a split-image focus ring, which is easier to focus than the plain matte glass or the microprism (an arrangement of many small pyramids that break up the image when it's not in focus). If you have corrective lenses, you should wear them to focus, or buy a diopter attachment lens for your viewfinder.

Age brings particular visual problems - your arms don't seem long enough to hold the newspaper so you can read it, for example. This condition demands bifocals.

If you wear bifocals, focus your SLR through the camera lens just as you would use your glasses to look at the same scene: Use the bottom (or near) viewing area for close-ups and the top (far) area for distant scenes. Unless you're doing some highly critical wide-open-lens focusing, don't worry if there's a slight discrepancy between how you can focus on a scene and how someone else does: The lens' depth of field will take care of slight errors.

Q. How can I improve my cloud pictures? They seem to me very faint, not as I saw them.

A. Overexposure of the sky is a common problem: Next time you shoot a cloud scene underexpose by one to two stops.

Another way to get better sky and cloud detail is to use a polarizing filter, which can give you the same spectular effect in color that you get by using a red filter for black-and-white.

The polarizing effect varies with the direction of the sunlight. To pretest the filter's effect, hold it up to your eye and rotate it while looking through it at the sky. You should turn completely around while doing this, to find the most dramatic effect.

Q. My electronic flash is always out of synch on the first picture I take; after that it settles down and works fine. Why do I have a problem with the first exposure?

A. Only a camera repairman can tell you why the first flash shot is out of synch; I would suspect shutter lag.

I can tell you how to check your synch, though.

Hold a sheet of white paper in front of your camera. Take the lens out and the back off, and fire your flash with the FX synchronization setting and the shutter speed recommended for strobe synch (usually 1/60th). Look through the back as you fire your flash at the paper. If the shutter is in synch, you'll see the complete frame in white; if it's out of synch you'll see only part of the frame.

Q. Where do I find ASA 64 on the film-speed dial of my 35 mm camera?

A. The setting for ASA 64 is the first dot, or dash, on your dial between ASA 50 and ASA 100. This number and others are not on the other dial because there's no room for them. Why some numbers are on the dial and others not is a mystery to me, since I don't use the marked numbers as often as the unmarked numbers ones. I bet you don't either.

The numbers I use most are ASA 64 for Kodachrome and ASA 125 for Type B Ektachrome and ASA 160 for Daylight High Speed Ektachrome. I also use ASA 250 for pushed Type B Ektachrome and ASA 320 for pushed Daylight High Speed Ektachrome. None of these numbers is on the dial. The numbers I use that are marked on the dial are 25, 50, 100, 200, 400 and sometimes 800 for pushed Tri-x black-and-white film.

At present, the dial is a mess: The numbers run from 6 to 6400 with a full-stop differences between the marked numbers and a 1/3-stop differences between those designated by the dots or dashes.

Operating the dial is like trying to guess the temperature using the Fahrenheit and Celsius scales simultaneously. It drives you crazy. I wish the film makers and the camera makers would get together and figure out a better ASA system - and I bet you do, too.