With my short experience, I will say this: It is a thicker version of any filter (UV, ND, etc) you screw on to the front of a lens. Depending on its "power," it allows you get very close to the subject, sometimes as close as a few centimeters. The "magnification" one gets depends on the focal length of the lens. Also, they say, you can stack them up to get higher and higher magnifications, but I have not tired that. Obviously, if your lens is a long telephoto type, you would have to use a tripod and, maybe a rail if you want to do focus stacking. Price varies from $10 and up on Amazon. Mine is a NiSi 58mm, which comes with a couple of adapter rings to go on 49 and 52 mm lenses.I've never heard of or used a 'close-up filter'. Is it same as a macro lens? That I've used.
Sounds like an opportunity to exploit the way they modify the qualities of the higher quality camera lens. Creatively. In a Lomography kind of way.I was playing with some of mine last night (a +10, a +4, and a split model of unknown strength) but didn't really have enough light, so my results were predictably poor. I don't think any of last nights were quality models (achromats).
Well no-ones like to rate my results as anything other than lomographySounds like an opportunity to exploit the way they modify the qualities of the higher quality camera lens. Creatively. In a Lomography kind of way.