MAKING MISTAKES is part of learning how to take good photographs. If you have ever misloaded your camera, forgotten to change the ISO rating or gone out on a shoot with dead batteries, you know how frustrating it is to ruin -- or miss -- a good picture.

However, I'll bet you've never made the same mistake twice!

I've made all the aforementioned common mistakes, as well as a few not-so-common ones. All my mistakes have helped make me a better photographer. Being aware of them might help you improve your pictures, too.

On a jaunt to Hong Kong, I shot approximately 60 rolls of film. When I had the film processed, one roll came back with a curved black line across the top of each frame. Evidently, a hair had fallen into the camera body near the film plane. Since then, I always check the interior of my camera every time I load it.

One winter night, I set out to photograph the Manhattan skyline from a bridge in nearby Queens. I composed the scene with the full moon at the top of the frame and a small campfire at the bottom. I thought I had a perfect picture.

When slides of my film were returned to me, I noticed that the automatic cutter, which reads the light and dark areas of slide film to determine where to cut it into frames, had mistaken the dark center portion of the scene for the edge of the frame. The result: All my slides were cut approximately in half. Now, in similar situations, when the edge of the frame may not be obvious to the mechanical slide-film cutter, I ask for processing only -- no mounting.

Another bad film experience happened the following summer. To keep my film fresh, I stored it in my freezer. When I saw a beautiful blue jay in my backyard, I took out a roll of frozen film, loaded it in my camera and shot away.

When the pictures were processed, I noticed that each frame was spotted. What happened? When the cold film was exposed to the warm air, condensation formed on the emulsion, resulting in spots. Now, I let frozen film "defrost" for several hours before I use it.

On another occasion, I was using a 28mm lens to shoot a beautiful sunset. When I viewed the developed slides, all four corners were blacked out. My mistake? With the 28mm lens, I had used a 50mm lens shade, which cut into the field of view. Now, I'm more careful when I'm doing even simple photographic tasks -- including screwing in look-alike lens shades.

Returning from my third international trip, I was greeted at the airport by a friendly U.S. Customs official who wanted proof that I owned my camera equipment and had not bought it in Japan. Since I had no proof that I owned the three camera bodies, nine lenses, two strobes and a myriad of accessories, the official said I had to pay duty -- several hundred dollars -- on the gear, which did look brand new.

I finally talked him out of charging me. Likewise, he talked me into registering my gear, serial numbers and all, with the U.S. Customs Office so there will be no question next time about ownership. If you plan to take an overseas trip, I highly recommend you do the same.

Rick Sammon writes for the Associated Press Newsfeatures.