One thing I have not seen mentioned here yet is a reversed lens - this is achieved typically by cutting out a camera-body cap and gluing it back to back to a cut-out lens cap.
As
@Petrochemist mentioned, there's like a jillion low cost adapters which do the same thing on eBay. I'd go with one of those for reversing a single lens (not to be confused with reversing the front lens in a coupled pair, but often not clearly distinguished).
(something typically 40 - 60mm)
(28 and 35 mm are more typical in my experience as less extension is required. The Lomo 3,7x finite objective, which is a 43 mm, is something of an exception. It probably has good availability in eastern Europe but, even pushed down, seems too much magnification for the OP.)
You lose AF, and normally aperture control as well (that depends on the lens), but you can get incredibly sharp results for very little outlay.
There are remote mount adapters to restore the functionality. Usually they're somewhat expensive, though sometimes people hack cables onto auto extension tubes a low cost alternative. Either approach can be expensive in terms of working distance.
Probably the tester of most interest here is
Robert O'Toole, who generally finds in favour of coupled lenses for ultimate quality, though
Mark Goodman and to some degree
Enrico Savazzi have posted rather a bit as well. Many of us would probably be happy simply to have Robert's budget, I think, and it's probably fair to say a well chosen single reversed lens can outperform a coupled lens arrangement capable of autofocus bracketing optically at similar cost as all of the funds are put toward image quality. A more complete analysis, which includes the focus stacking rail and mounting hardware for a single reversed lens, tends to favour autofocus from coupled lenses. Autofocus bracketing is relatively new, however, with less identification of good coupled lens combinations.
IMO using a supplementary dioptre with a lens in the region of 18-20mm is a sign you don't understand their use!
Hi, I think you've confused f₂ for f₁. Coupled pairs with f₂ = 18-20 mm typically implement it by using a 10x infinity corrected microscope objective as the front lens. The rear lens is usually chosen for magnification in the 5-15x range, therefore being 100-300 mm-ish.
My microscope claims 1600x max but in reality anything more than about 400x is empty magnification, and photographs struggle beyond ~100x. DOF on all these is REALLY short. Stacking 7 shots across the width of a flies foot proved far too little and I couldn't adjust the focus control subtly enough to manage more.
Yeah, I'm not really a fan of 1000+x, preferring to work at 400x when I can get away with it, which is usually. The scopes I use most regularly to do yield at 1000x but get fiddly with the condenser.
If [you're] after magnifications above 10x, you've gone out of the realms of macrophotography & into photomicrography (using a microscope).
Mmm, 20x objectives at 10-30x are fairly common in ardent studio macrophotography (not that vibration isolated, optical table-like studio macrophotography rigs capable of that magnification are common). A few people do go up to 100x objectives in macrophotography, though 40 and 60x are
more common less vanishingly rare.
For now I'm not really motivated to use more than a 10x objective in the field but I could probably push my current setup to 18x if I had to. It's easier than studio in that there isn't urban vibration to manage, harder in that lighting has to be portable and that wind makes subject and camera motion.
Moss communities have the great convenience of usually being under the boundary layer (mat formation is a communal exohydry optimization for individual poikilohydry) so at least subject motion is generally pretty low.
