Gerry, As others already pointed out, you are mixing up things. Ken already explained the use of those gadgets to invert a lens on your body. Please see the e-mail of our dear admin WJM about a report on the use of the 28-135IS for this purpose (pasted below).
The technique you describe is better known as "inversed lens technique" (instead of "reversed") and your description is quite accurate: you inverse a lens (short to std) on a tele. The magnification you achieve is about mm(tele)/mm(inversed lens), but it depends sightly on lens construction. For example, internal focusing makes a big difference. I achieve about 3x with the 50f/1.8 on the 100f/2.8 Macro USM, as you see, the plain numbers don't match. The 75-300IS makes a good combination with the 50f/1.8. You can use any kind (read brand) of lens to inverse on the tele, and it *MUST* be wide open. The wider the maximun aperture, the better. The combination 75-300IS with 50f/1.8 is good for a range of 4x-6x since it vignetes with the shorter focal lenghts than 200mm. You can help that with some extension tubes, but you increase diffraction. Please note that this combination is *extremely* unstable and the use of a good tripod in a controlled environment is a must. (Field use is *very* hard although not impossible). Means of fine-tuning composition and focus is another must (ie. focusing rail, helpful tripod head). At 6x, any movement of the camera body, changes the framing completely. You may experience some serious exposure problems as well... about 2 stops off, so bracket a lot. About how to inverse the lens on the other, I just glue two Cokin ring adaptors together. Just buy the right one for each lens and use a very strong glue to 'solder' them together. Much cheaper that those custom inversion rings (with threads of different diameters at both sides) (& also hard to find) One more thing: Please don't cry when you get your slides back. The results are not going to be what you expect. If you have more questions, please let me know. I've *wasted* quite some film on this technique. ;-) ;-) I can help you to trash some as well ;-) ;-) Greetings, Gerard. PS: Using flash with this technique is another post as long as this one. PSS: Here is the e-mail of WJM. I really don't know how Julian does to find the URL's . This report looks really interesting. I just have no budget for the Novoflex gadget at this moment. Anybody have tried to DIY one reverse adaptor from a extension tube? -------- Original Message -------- Subject: IS zoom-micro / Novoflex EOS reverse-adapter Date: Tue, 10 Jul 2001 21:27:23 +0100 From: "Willem-Jan Markerink" <[EMAIL PROTECTED]> Reply-To: [EMAIL PROTECTED] To: [EMAIL PROTECTED] CC: [EMAIL PROTECTED] (extending previous thread on EOS-list, CC to PhotoForum list for technical novelty of the constellation) Hmm....not much reactions on my previous posting about this topic on the EOS-list, where a Novoflex-reverse-mounted EOS zoom was found to be equal in quality to a Zeiss Luminar....;)) http://www.weihenstephan.org/~joachenk/makrozoom.html (sorry, all German; the summary of that article is that the quality is explained (and confirmed by Zeiss!) with the fact that the reverse-mounted lens uses only a very small center part of the original optics, and that center is relatively easy to design near-perfectly (a similar explanation exists for the question why the EOS 24/3.5 tilt/shift lens hardly looses any quality when combined with a 2x converter). But perhaps this second thought will get some more attention: The zoom used in this reverse-constellation is a 28-135/IS. And I see no reason why the Image Stabilisation might not work in this case. So effectively you have a zoom-micro ranging in focus/magnification from infinity at 135mm to 3:1 at 28mm, handholdable at that point up to 1/8s at least, 1/2s or even 1s most likely, especially when combined with a monopod. Also a rather cheap alternative to the only other zoom-micro's out there, a Zeiss Tessovar or Zoom-Luminar....:)) (with the difference that these are relatively (very) long tele's, and offer a much better subject-distance) -- Bye, Willem-Jan Markerink * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
