WITH SUMMER upon us, it's time for some advice on heat, beaches and boating.

First, heat, especially in closed automobiles, can be a dangerous enemy. It doesn't matter whether it's in or out of a camera, film can be affected by high temperatures in just a few hours.

I always try to carry my film in my camera bag so it's with me all the time, especially when I leave the car. If I'm on a trip, I start out with as much film as I can easily carry, and if I run out, buy more.

If I know that stopping to buy will be inconvenient, I put my film in self-sealing plastic bags in a small styrofoam cooler with a couple of refreezable cold packs. This keeps the temperature down for most of the day, depending how often the cooler has to be opened.

Remember that if a person can stand the heat, so can film. As I get more uncomfortable, I know that my film is, too.

About beaches: Three problems: Sand, water and reflection.

Unless you have cameras specifically designed to be submersible or at least resistant to water and sand, you must exercise great care. In fact, some of the compact "auto-everything" cameras will stand the surf and sand better than many of the sophisticated SLRs.

Common sense is the rule; wrap your camera in a clean, soft towel and carry it in a plastic bag to keep it dry. After you've made pictures, rewrap and you'll be safe.

One grain of sand in an unprotected place on your camera can ruin a whole day's shooting and mess up your camera to boot.

Light reflected from sand and water is generally extremely bright, so bright that it can wash out some of your pictures, so meter carefully. If you are able to adjust the ISO on your camera, try shooting both one notch higher and one notch lower than the rated speed. This will give you some great effects.

For boating, use a plastic bag to protect your camera when you're not shooting. I also recommend the Sports Pouch, made by the Sima Products Corp. It floats and is said to be waterproof. These are available at sports stores, camera shops, and specialty places such as L. L. Bean and Eddie Bauer.

Q. I want to photograph the inside of an old railroad station which is boarded up. I can see inside and it is very dimly lit -- just a couple of hanging lightbulbs.

I have a Konica T4 with a Hexanon 50mm f1.7 lens. Can you tell me how to shoot this dark place?

A. You will need a tripod, not only for this situation but for a lot of others. If you have to poke your camera through a small opening to shoot, just be careful that your lens is not blocked -- and you can tell what you're shooting. Try to get a meter reading and go from there. Be sure to bracket; run a full range of f stops and speeds.

I would recommend using 400 ISO black and white for your first roll. After development you can tell what to do next.

Don't neglect the outside of that building. Make some general scenes, but be sure that you shoot details of boarded-up windows, a roof in disrepair and any other shot to show the age and neglect.

Best of all, try to get permission to get inside the building. I would try community officials or police to establish the ownership. You'll get the best pictures by shooting the inside from the inside.

Q. Due to illness I could not do anything about my Kodak EK6 instant camera. Can I still turn it in? Have you heard anything more about this?

A. Nothing is being done at this point about turn-ins since there is a suit pending against Kodak concerning their trade-in offer. The suit claims that Kodak isn't offering enough for the cameras. While the litigation is in progress, there will be no action. When all this started, one of the offers was to trade the cameras for a share of Kodak stock. Then it was at $50 a share; now it's about $80.

Last call for the helpful photographic hints contest. Entries have to be in by the end of this weekend. A set of Kodak big print mailers will be awarded for the best entry.

Carl Kramer deals with questions of general interest but cannot answer letters individually. Send queries c/o Weekend, 1150 15th St. NW, Washington DC 20071.