Quote Originally Posted by leadduck View Post
This used to be a great method with manual cameras. However, I've never seen a reveral ring for an autofocus camera and I can't even imagine how it would couple with the camera's electronics. I've had good luck with a closeup filter screwed on to the front of the lens. (Not as good as a dedicated macro lens, but ot $400 either!)
I might be wrong, but this is what I know

What the rings does is to increase the flange distance between the first element and your sensor / film, it has nothing to do with the camera electronic, in fact you camera won't meter unless if the macro ring has/provide an indexing function (newer branded vendor provides that + auto focus function)

the ring are actually just a "good" representation of pringles can/plumber pipe, which usually used to do the job done.

if you use filter lens then it will increase another element of glass which the light should pass, and that has the possibility to decrease the sharpness (unnoticeable) and color fringing. if you use the ring or any other similar attachment the sharpness will retain but you need longer exposure.

if you use reverse lens, the number of magnification could be vary depend on your focal length, I do recommend prime lens to be used here

another way is to use microscope directly attached to your camera. it's hard to get the attachment for digital but previously in 70-80's (gosh, I'm not even born yet ) several camera like Olympus Pen, Yashica ???(forgot the series) and pentax 110 could do the job easily and they're popular in science, medical and biology lab.

specifically for photographing a razor (for display or observation) I guess the best way is to use prime lens to keep the detail and other effect (blue light, soft corner, etc.) that you might not want (unless you like and fine that of course), second is big soft/diffuse light source, preferable 6x than the object size so the shine from the blade or the scale could pop up (haven't tried this on razor, but this is the technique when I did macro/product shoot).

regard,

Erick