Q - I know I should use a tripod for long exposures, but sometimes it's just inconvenient to carry one. Then I find myself in a situation where I need one and don't have it with me. Is there any way to shoot slow exposures without a tripod?

A - I'm as lazy as you are, so I've had to figure out how to shoot without a tripod on many occasions. Surprisingly, there is always a handy tripod around regardless of where you are. The trouble is that it doesn't look like a tripod, which makes it hard to find.

One of the simplest and handiest supports is a door frame. You can hold the camera against the side of a vertical or push it up under the top jamb for a horizontal format. The trick is to find a level part of the molding so that the bottom of the camera is in full contact, then push against the support when making your exposure.

For the top of the door turn your camera upside down and stand on a chair or stool if you want to see through the viewfinder. Actually, it's not necessary to look if you've taking a general view of a room interior.

Outdoors, the same idea works as well - use a pole or even a tree trunk for verticals. For horizontals, the top of walls, a large rock or a rock pile will do. All you really need is a firm surface on which you can rest your camera. You won't be able to move to an exact location as you can with a tripod, but often the viewpoint is close enough.

Q - I keep cutting off my subjects' heads when I take pictures. is there any cure for this?

A - Yes, and it's a very simple one. Turn your camera to the vertical instead of shotting horizontally.

Like all simple solutions, this may sound too obvious. Yet surprisingly, as you look around at people taking pictures, you see them holding the camera horizontally when the picture just cries out for a vertical.

This is especially true of pictures of people. If the photos is of a single person, or even two or three, a horizontal framing will leave waste space on either side and, if you move in closer for a bigger image, there is a danger of cutting off heads.

The vertical format will also help you get bigger-headed portraits that will give better enlargements because the image on the negative is larger.

Besides helping you keep your heads, there are other advantages to a vertical.

By changing your camera view to an upright one you can often find a composition that is different and sometimes even better than the horizontal.

And if your picture aim is reproduction, verticals are essential. Magazine pages are vertical, and so are newspaper columns. Often a picture layout or a magazine cover just has to have a vertical, and the horizontals won't crop to the right proportion.

It's a good idea to get into the habit of turning your camera up and looking at the picture both ways before shooting. You may decide to change or even shoot it both ways.

Q - I notice that in photography books and magazines, color transparency film is used, not negative color. Why?

A - Color separations are made directly from the original transparencies, most usually through a direct scanning process. This can't be done with color negative material, which first has to be printed in true color.

Each time a change is made from the original the result is poorer. So direct separations from a transparency have better color fidelity than those involving the added step of having a color print made from the negative color first.

Transparencies also offer the added advantage of showing exactly how the original colors were, so that editors and art directors can check on the quality of separations.