>I'm planning to try out reversing a lens for macro work. I'm interested in >getting approximately 3x magnification. I thought that this technique >worked by mounting a second lens reversed on the front of the first lens, >giving a magnification equal to the focal length of the main lens divided >by that of the reversed lens (50mm reversed on 200mm lens gives 4x >magnification).
Ok, with this setup you get a 40mm efective lens focused to a distance that gets 4x. >But when I looked on the web for reversing rings, I found a lot of items >for sale that are specific to a particular mount. For example, on the B&H >site, under the macro accessories section, "Reverse adapter Canon to 52mm". >But shouldn't these things be generic, as it simply involves connecting the >fronts of the lenses via a ring with a screw thread on each side? Or have I >misunderstood the technique? This is another technique as others have explained. >I'm also wondering which lens to use. I have three reasonably long lenses: >180mm macro, 100-400 IS, and 75-300 IS. If I understand the technique >correctly, I'll have to use the 75-300 (which would not have been my first >choice) because the reversed lens must have a diameter at least equal to >that of the main lens in order to avoid vignetting. So either I use the >75-300 (58mm filters), or I have to find a short lens with a wide body >(72mm and 77mm filters respectively for the other two lenses). I would use the 180mm macro to get 3.6x. Zoom lenses usually work worse if the are used out of their specs. Don't know the vigneting you could get. >Can I use an EOS lens as the reversed lens? It has to be wide open, so I >guess there's no problem (can't be controlled electronically, as it's >reversed). Ok, an EOS lens will be as good as whatever open wide lens. > I was thinking that I might reverse my EF 50mm f/1.8 on the end >of the 75-300mm lens, to give a 1.5x-6x macro combination. I don't mind >buying a non-EOS lens to reverse on the end of my EOS lens, but I'm trying >to do this reasonably cheaply (in other words, buying the MP-E 65mm macro >lens is not an option at the moment). You can also buy a screw M42 adapter, a M42 bellows, and a M42 wide angle to get big magnifications. That will be a quite cheap setup. The m42 wide angle can be reversed to obtain better quality. You can also use an (reversed?) enlarger lens on the bellows instead. Of course you would need to metter stopped down. TTL flash will work ok. I have gone to 1:1 using my EOS 500n (Rebel G) and a Pentax Super Takumar 50mm f/1.5 M42 on M42 extension tubes. All works ok. I can get a M42 bellows for less that 50 USD. That will be the way I would go if a wanted to cross the 1:1 line. >Gerry Best regards Vicente * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
