A tip. To get the maximum depth of field (the near and far points of the subject that are in focus) you need to use small'ish apertures. To be able to use small apertures you generally need lots of light. You'll undoubtedly need a flash but it'll have to be mounted such that it lights the subject from above and/or to the side(s). Having a flash fixed to the camera will almost certainly result in images where the subject is in the shadow of the lens. A diffuser or alternative mounting is preferred, or use a ring flash which mounts to the end of the lens.

You're welcome. Now let's see some results.

Any zoom lenses you see having 'macro' in the description are not true macro lenses. They merely have a mechanism which allows them to focus at closer than normal distances. Some have the macro setting at the long end (useful), others at the short end (less than useful in my opinion). Truth is, the macro mechanism on these lenses creates the same effect as using an extension tube, they simply extend one or more lens elements away from the body in much the same way as an extension tube does.

The true macro lenses, those capable of 1:1 macro's, are fixed focal length.

1: It is.
2: It doesn't.

But you said "I can't afford anything" ! ! !

A macro lens is designed such that it can focus from infinity down to very short distances. When focussing at these short distances, its behaviour is not dissimilar to a normal lens (anything from 50 - 100mm'ish) mounted on extension tubes. The latter will not focus at infinity though. The shorter the focal length of a macro lens means that you can (need to) get closer to your subject.

My own preferred macro lens is the SMC Pentax-FA 100mm 1:2.8 which you can see here.

My suggestion of stacking lenses was based on my assumption that you might already have suitable lenses.

Those two lenses are not best suited to stacking together but you could certainly get hold of a SMC Pentax 50mm 1:1.7 lens reasonably cheaply. Then fix it to the front of your 50-200mm zoom.

BTW, I don't think your account will be banned. Ridiculed, you might be. Belittled, occasionally. But banned . . . probably not, as long as you display some first class results here.

Now that's a difficult one, let me think . . . .

Which lenses do you intend to use?

The SMCP-F 70-210 and the SMCP-F 50 both happen to have 49mm filter threads so a stacking ring was easy to find. Ideally they should both be the same. If you have a zoom with a large filter thread, and a 49mm threaded 50mm lens for instance, you will get vignetting. But your favourite editing software can fix that.

BTW: Macro is much more rewarding with a digital body beccause you can see your results much faster and make necessary adjustments. Not so with film.

Have fun.

With regard to protecting the contacts: Get hold of one of the older push-on Pentax rear caps. Cut out the centre and mount it on the reversed lens so that the contacts and mechanics are protected.You can do this with the hard caps as well but the soft ones are easier to cut.

You should be able to get a male to male adapter, or stacking ring, from Jessops but you will have to know the filter sizes of the two lenses you intend to stack.

Extension tubes are another method of producing macro images. Usually sold in sets of three tubes of differing lengths. These are usually 12, 20, and 30mm'ish and can be used singly or in any combination of 1, 2, or 3 tubes to give varying magnification. To keep things very simple, the use of extension tubes emulates the function of a macro lens, but a bit more fiddly. they are placed between the camera body and the lens to create an air gap or . . . extension.

No, much better. That one was taken with a Canon.
If you have two suitable lenses and appropriate lighting, or strong daylight, just try it. Then come back and show us some macro pics.

I did exactly this the other day. SMCP-F 70-210 on K10D, SMCP-F 50mm 1:1.7 reversed. Then SMCP-FA 100mm Macro on fully extended bellows, then the same with a 50mm on fully extended bellows. The stacked lenses gave me the highest magnification and little difference in DOF. The shots were just of a 10 centimos coin and handheld so I'm not going to post them here. It was just an experiment anyway. Good luck.

Set the aperture of the 50mm to wide open, then you have all the exposure controlled by the zoom lens. AF is not likely to work but macro shots are best attempted using manual focus anyway.

If you've never tried it, you'll be amazed. As a test, simply hold a 50mm lens reversed against a 200mm lens or similar. DOF is next to nothing, but hey, that's macro for you.