100mm macro with reversing ring

[rya794]

I have a couple questions about using a 100mm macro with a reversing ring.

If I use this set up will I still have manual focus capabilities with the 100mm macro?

What kind of magnification can I expect to get if I use a 50mm lens on the end?

How will the quality be affected?

Thanks
Ryan

[DaveG]

I have a couple questions about using a 100mm macro with a reversing ring.

If I use this set up will I still have manual focus capabilities with the 100mm macro?

What kind of magnification can I expect to get if I use a 50mm lens on the end?

How will the quality be affected?

Thanks
Ryan

The question I would have with a reversing ring on an EOS lens is how do you change the aperture? On conventional lenses there's an aperture ring on the lens and obviously there is none on an EOS lens. The aperture is controlled by electronic linkage to the camera body.

When the lens is reversed the linkage is separated and while I guess you could hook up something to the exposed (and now forward-pointing) lens contacts, I don't see how you can link that infomation to the camera since the camera's contacts are hidden behind the mounted lens.

Maybe Canon has figured out a work around for this that I'm unaware of. But unless you want to do all of your macro/micro work at f2.8 this needs to be addressed before any of your other concerns.

[Cal Maier]

The question I would have with a reversing ring on an EOS lens is how do you change the aperture?

You would have to use a 50mm manual focus lens that has an aperture ring. Any old 50mm lens would work, Canon, Pentx, Nkn, it doesn't matter what brand, although some of these old lenses are sharper than others, of course.

I have not done any close-up work using this method, and can not offer any good answers to your questions, but I do wonder if you would get better results from your 100mm/2.8 if you were to use extention rings in order to get better than 1:1?

Cal M

[pturton]

Results of a quick test:

Using 58mm f/1.4 set at infinity and aperture f/1.4 reverse mounted on Canon 100mm f/2,8 Macro lens which was focused to 1:1.

10D sensor size 22.7x15.1 mm
Horizontal field covered 8.1mm
Magnification = 2.8
Glass to subject <20mm

This setup may be usable for indoor controlled conditions with a flash but certainly it would be difficult to use in the field.

Paul

[Hatem Eldoronki]

Autofocus won't work. I have a ring, and I hardly ever used it, because it's a pain in the neck (literally). I can tell you that the depth of field will drive you crazy! I connected the 100mm macro, and reversed a 75-300mm on it, and the magnification was unbelievable. I tried the 100mm and reversed the 50mm f1.4 on it, but it was easier for me to just screw on a +1 close-up lens to get the same magnification, rather than reversing the 50mm...

[Loekito]

I have a couple questions about using a 100mm macro with a reversing ring.

If I use this set up will I still have manual focus capabilities with the 100mm macro?

What kind of magnification can I expect to get if I use a 50mm lens on the end?

How will the quality be affected?

Thanks
Ryan


Basicly here's the magnification rules on reversing other lens in front of another lens.

the magnification factor = lens focal length / reversed lens focal length

so, if you reverse 50mm lens in front of 100mm lens, you will get 100 / 50 = 2x magnification

I tried to reverse old 50mm manual lens into my EF 100mm f/2.8 macro using my digital rebel. put my 100mm in infinity (not in 1:1 focus), and I get about (as if) > 3x (3 point something_ magnification (because of 1.6x crop factor)

regards,

Loekito