Q. Will you please discuss the pros and cons of a 50mm vs. a 100mm macro lens? I have a Canon EOS 620 and would like to get a macro lens primarily for wildflower photography. Which would you suggest?

Q. Can you tell me if anyone makes just a plain macro lens any more for my SLR?

Q. I have just discovered that the lens on my 35-70mm zoom has a green area marked "macro." I have messed around with it some and tried to make some close-up pictures of flowers, patterns and even some animal life. It seems to work OK but a person who is allegedly a professional photographer told me that it was a "second-class" way to shoot. She says I should buy a macro lens for close-up pictures. Is this true?

A. There are some very fine macro lenses on sale. They have improved so much that I consider macros among the best kinds of lenses made.

As a general rule, I prefer the 100mm to the 50mm. With the 100mm you will work a little further away from your subject -- a much easier way to shoot. The 100mm is a little heavier than the 50mm, but not that hard to carry.

The 50mm is a great lens to use with a bellows arrangement; the combination of these two enables you to make close-ups of a praying mantis's eyeballs. For the EOS, Canon makes both a 50mm and a new 100mm that I have been told is a wonderful lens.

I don't agree that the macro settings on the new SLR lenses are second class. I have several and use them a lot. I have found that they are sharp and easy to focus. And, of course, there is the all-round versatility given by the rest of the settings.

Q. I am interested in obtaining a Vivitar 28-210mm zoom lens. I have examined this lens being used by a friend and I believe it would be the solution to my present equipment, a 28-90mm Vivitar and a 70-210mm zoom Vivitar. I find myself hardly ever using the 70-210mm because it is heavy and I find it awkward. Have you anything to add about that 28-210mm that would help me make up my mind?

A. I have not yet tested that lens, but I've spoken to several people who have. Both reports were favorable. The sharpness and resolution of the lens is apparently very good. As for weight, balance and ease of use, that's a very subjective thing and you'll have to make that decision yourself.

Until recently I was somewhat suspicious of the zooms with the super range. Then I tried both the Pentax and Minolta 35-105mm zooms and knew we were on the way. I have just finished shooting with the Ricoh 28-200mm and was delighted with the results. Canon has a 50-200mm lens that EOS users are raving about.

Q. Please tell me how to take pictures of the night sky, particularly the moon. I have a single-lens reflex camera with both a 35-70mm zoom and a 70-210mm zoom. Do I really have to have a big telescope and a moving equatorial mount to do this?

A. No. Although using a powerful telescope with a motorized guided mount can allow you to photograph nebulae and very faraway objects, you can make very rewarding pictures with the equipment you have.

The most important thing you'll need is a really dark environment. You've got to get away from "light pollution," and this is no small task. The deserts of the Southwest and many of the national parks are great. At the Seashore National Park at Cape Hatteras, N.C., I found great places to view the night sky. On a clear night the moon seems very close.

For that reason, don't let yourself be fooled. That moon, especially the full moon, is extremely bright. I work in the program mode when shooting the moon, and the through-the-lens spot meter does the work. You'll find that with ISO 100 film you'll be shooting about 125th of a second at f-8. I like the shutter priority mode so that I will get as much speed and as little f-stop as possible.

I like to shoot slides for moon pictures. On a crystal-clear night (usually in the winter), I would use either Fuji Velvia or Kodak 100HC.

To make star pictures you'll have to use a tripod and make time exposures. I find I can usually shoot up to 25-30 seconds without getting "star trails," or the moving path patterns. You can also make some great pattern shots by leaving your shutter open for minutes.

Write Carl Kramer c/o Weekend, The Washington Post, 1150 15th St. NW, Washington, DC 20071.