Q. You have a lot to say about the new automatic cameras. You say how great they are and give the impression that you get a lot of camera for the dollar. That's fine, but I think you do your readers an injustice by not telling them how much it costs to repair those things.

A. No injustice intended. Repairs are indeed very expensive on the new, electronic cameras. Labor costs range from $12 per hour upward. And a repairman I trust completely told me that just to open the top of some of the electronic cameras breaks a circuit board that costs nearly $100. That's for starters.

With that kind of money involved, there are two important things to remember about protecting your investment -- preventive maintenance and the manufacturer's limited guarantee.

* The limited guarantee covers defects in parts or construction of the camera. It is not, however, a guarantee against abuse, like dropping the camera or letting it fall into a pail of water. It's up to the camera maker to decide if the guarantee should be honored. Let me quickly say that I feel the major camera companies are absolutely honest. They are, after all, expert on their own gear and can pretty well establish if someone's trying to pull a fast one.

Usually a mechanical or electronic defect will show up very quickly -- perhaps in the first three or four rolls. Certainly your camera store and the manufacturer will stand with you in this case.

But remember that a "limited" guarantee is just that.

By the way, be sure to send in the registration card that comes with your camera. If it's missing, ask your salesman for one. The cards are becoming more and more important in establishing your guarantee.

At most reputable camera stores, the personnel will explain everything about your purchase, including repairs, maintenance and guarantees. Don't leave without getting a full explanation.

* As for preventive maintenance, if you give your camera common- sense care and handle your camera like the delicate instrument it is, you can go for years without spending that big repair buck. A $100 repair bill spread over five years ain't bad.

You can buy a cleaning kit for about $5. It will contain a blower brush, lens tissue, lens-cleaning liquid and cotton-tipped swabs.

After shooting, use them to clean your camera and flash. Clean around the controls, wipe your lenses and viewfinder, and don't forget the lens mounts.

Don't poke inside the camera. Don't touch the mirror or the focal plane shutter. If you're not going to use the camera for a while, take out the batteries, clean the contacts and wrap the camera in a soft towel.

And my favorite warning: please watch out for extreme temperature changes. Glove compartments in summer are deadly. In winter, coming out of a toasty-warm room to near-freezing outside temperatures will fog your mirror and lens. Give your camera a chance to get used to things.