macro rings and invertergreenspun.com : LUSENET : Canon FD : One Thread
Hello, I recently got an inverter (to mounte the lens back to front) for some macro photo. First question : why the focus ring on the lens seems to do nothing (the only to focus is to be more and less close to the subject) ? Second question : what if I use some rings with the inverter ? Will I have a better enlargement (and less light, of course)? Does it worth the purchase ? And by the way, what is the best, the rings or the inverter ? Thanks
-- NicolasLL (Nicolas.Leste@obspm.fr), March 15, 2001
In general one leaves the lens focused at infinity with a reversing ring and focuses by moving the camera. If you are using a lens that focuses as a single group (all elements move together, without internal focusing or floating elements) like the FD 50mm/f:1.8 (this inexpensive lens works quite well in reverse--better than the 50/1.4 or 50/1.2L in my experience), the helicoid normally moves the elements back and forth with respect to the barrel. With a reversing ring, the elements stay in one place, and the barrel moves back and forth, having no effect on the focus.
Yes, you can combine a reversing ring with extension tubes to get closer to the subject for greater magnification. Generally, you would use the lens in the normal position with extension tubes for magnifications up to 1:1, and you would reverse the lens for magnifications greater than 1:1, but you should make some tests with the lens you plan to use, since the optimal point at which to reverse the lens is not always the same.
Another interesting thing you can do with a reversing ring is to reverse mount enlarging lenses on your camera, if you happen to do your own darkroom work and have them on hand. You will need a step-up ring to attach the lens to the reversing ring. Reversed enlarging lenses are usually very well corrected for larger enlargement factors and flatness of field (that is what they were designed for).
Whenever using any kind of lens reversed, be very careful to shade the rear element from stray light, which can cause flare and reduce contrast.
-- David Goldfarb (email@example.com), March 15, 2001.