Hi,
I've been reading about the 35 mm adapters for a while now. My question is: what exactly is an achromat? As I understand it it's a basic closeup lens to use with the adapter and is included in the price with many of the adapters that are for sale.

Am I wrong??

"Achromat" is easyspeak for "Achromatic Dioptre" ("Diopter" on the US side of the ditch.)

A = (not) + cromatic - sort of.

In short the achromatic dioptre confers a better image.

It is a better than basic close up lens.

The reason it confers a better image is that there are more than one piece of glass in it. Why it works better is too much high science for me.

In practical terms, it does not cause rainbow effects out towards the edges or corners of the image where a sharply defined object of high contrast occurs in the shot. In a highly textured background such as a flower laden garden or autumn leaves mixed up with some green, the colours are also crisper through not being blended into a muddy average.

There is apparently another even better device called an apochromatic lens but this is even higher science beyond my knowledge. A previous poster here, Brett Erskine knows about them. A search under his name may yield the info on those.

Simple close-up lenses, also referred to here as "macros" with one piece of glass in them can give a result if they are not too small a diameter and the camcorder sees through the centre of them.

The popular practice of stacking a +1, +2, +4 to get +7 is okay to prove you can frame the required groundglass image in a home made appliance before you pay out on a good dioptre which may not be the right power.

If the objective of making an appliance is to add production value to your projects there really is no substitute.

Appliance...I like that. I need a food processor attachment for mine.