Reversing Rings for Macro Photography

[klindup]

I recently saw some fantastic results a friend achieved by reverse mounting a Distagon on the front of a Planar on his Hasselblad.  The resulting close-up photographs were used as covers for a couple of professional electronic journals.  I would like to try reverse mounting a wide angle onto the front of a Canon 70-200.  My question is , where can I buy the necessary reversing ring?

[Bob Atkins]

Well, first you don't want a reversing ring, you want a macro coupling ring.

A reversing ring allows you to reverse a single lens. One side has a lens mount, the other side has filter threads.

A macro coupling ring has male filter threads on both sides, so you can screw one lens onto another (facing each other).

The trick will be finding a macro coupling ring that goes between sizes. Normally they have the same size threads on each side. If you want to couple between lenses with different threads you'll also need the appropriate step-up or step-down fiilter adapters.

Adorama carry all sorts of step-up, step-down and macro coupling rings. You'll have to dig around to find the sizes you need. Here are some examples to start you off.

 * 62mm-62mm macro coupling ring
 * Step up ring
 * Step down ring

Your best bet would probably be to start with two prime lenses, such as a 100mm prime with a 50mm prime reversed. That will give you 2x. Mounting a wideangle lens reversed on a telephoto zoom might give you some problems. Maybe vignetting, maybe some quality loss. You don't have to reverse a Canon EOS lens of course. You can use any lens, including lenses with a mechanical iris which you can adjust.

[klindup]

Thanks Bob I will go looking.  The logic between the use of macro coupling rings as I understand it is that the lens that you couple to the main lens will be better corrected and have a flatter field than a conventional close-up lens.  What is your view, will I be likely get the same or better results with a Canon two element close-up lens?

[Bob Atkins]

Using a reversed lens coupled to a longer lens is mainly done to get high magnification. It's easy to get 2x, 3x or 4x magnification. Magnification in simply the ratio of the focal lemgts, so if you mount a 50mm lens reversed on a 100mm lens, you get 2x.

The two element close-up filter (diopter) is used to get lower magnification. It depends on the lens but you'd typically be in the range of 0.5x to 1x.

The closeup lens is a lot more convenient. It's smaller and lighter and you only have one lens to worry about. In terms of image quality I doubt you'll see much difference. While photo lenses may be better corrected for normal use, they're not corrected for use as closeup lenses when reversed and mounted on a second lens.

If you just want to do good quality macro work and don't need to go above 1x magnification, I'd go with a close-up diopter.

You might want to take a look at these articles:

http://www.bobatkins.com/photography/eosfaq/closeup2.htm

http://www.bobatkins.com/photography/tutorials/macro_lenses.html

I do see that the Canon 250D and 500D closeup lenses seem to be out of stock everywhere, except for a few stores with names I don't recognize who are selling them for about twice the price that Adorama and B&H charge. I don't know why they seem to be in short supply right now.

[klindup]

Thanks Bob I understand the logic now.
Ken