>>3597669>So, about those distance rings mounted between lens and camera
Extension tubes. They turn every lens into macro.
The reason macro lenses can focus close, is because they have a longer barrel and helical, which allows the lens to move further away from the sensor, allowing it to focus closer.
With extension tubes you introduce that extra distance yourself to any lens.
The "con" is that in theory a macro lens has a formula that is optimised for close focusing distances, or ideally a floating element design that allows optimisation throughout the focus range. The reason being, at closer focusing distances, imperfections around the corners are exaggerated, so some that were invisible (and thus uncorrected) in normal focusing distances, become visible in close distances.
That said, some lens designs perform really well at close distances, even when they were not designed for it.
Another "con" could be that extension tubes are fixed and offer a set amount of focusing range. If you want to focus on something out of that range, you need a different length extension tube (but on the plus side, they can be stacked).
In any case, extension tubes provide a good, very budget friendly intro to macro.>or magnifying glass mounted like filter
Many optical aberrations, and in general shitty image quality.