Step down rings

[animator]

Hi All. New to the forum and Macro photography. What is a step down ring please? What is it for? Do I really need one? What's the purpose? Any good url's for macro photography please?

[daft_biker]

In macro a step down ring is sometimes used to reverse a lens with a smaller filter thread onto another lens.

By reversing a wider lens onto a telephoto lens you can get pics taken atmacro magnifications. For example a 50mm reversed onto a 100mm should give around 2x (2:1) magnification because the 100mm is 2x the focal length of the 50mm. With a 24mm reversed on a 100mm you should get around 4x (4:1) magnification.....the greater the difference between the shorter reveresed lens and the lens mounted to the camera the greater the magnification.

What camera and lenses do you have? What kind of macro do you want to do?

[animator]

Hi Andrew and thanks for your reply which I found helpful. I have a Pentax K100D with an 18-55mm lens with a 52mm thread on the end. I have four other lenses I could use with it from a 28mm to a 300mm. Most are all different sizes so guess I would have to buy 4 or 5 sd rings. Also, do you know if you can buy a 52mm to 52mm ring please? At the moment I have used the macro on the lens to photograph a few flowers but I am really interested in various bugs and insects and anything else that may take my fancy