Steve. On the Rebel (and I would guess on any of the crop format cameras) you do not loose any of the frame. If you wear glasses, that might be a different story. I comfortably see the whole frame w/o having to twist my eye around at all. The magnification is not that much. A friend tried it on his 5D mark 2 and with his glasses he said he did loose quite a bit of the frame. I did not look through the finder w/o glasses to see if I could see all the frame. Perhaps others in the group could shed light on this. Aram From: Steve Lang Sent: Saturday, August 01, 2009 12:41 PM To: leicareflex@xxxxxxxxxxxxx Subject: [LRflex] Re: Summicron 50mm take apart? Hi Aram, Thanks for the tip. From reading the description and reviews, I guess you end up losing some of the frame due to the magnification? I took my daughter to her horse-riding lesson this morning, and had fun with the XSi+Summicron. Actually, I think I finally 'grokked' manual focusing, and why many prefer it to auto. You have to be actively involved in the picture-taking, planning and predicting shots. But you also get a level of control over the final outcome not possible with AF. I bought the Leicaflex and Summicron with the intent of taking more deliberate pictures, so this is perfect. Since it was bright out, I mostly shot at f4 and zone-focused with good results, not too hard since she rides in a ring. (And hey, now I understand why DOF scale on a lens is so useful!) I am definitely going to go for a focusing screen in the near future. I'm planning on keeping the Cron on the body full-time, so there's little reason not to. It's too bad the AF confirmation lights don't work with the focusing screen, but it's not a big deal. On Sat, Aug 1, 2009 at 6:37 AM, Aram Langhans <leica_r8@xxxxxxxxxxx> wrote: The other option that I use, and maybe a few others on the list, is the Nikon DK-21M viewfinder magnifier. It fits on the Canon and allows a small, yet significant degree of magnification that really aids in focusing. http://www.amazon.com/Nikon-DK-21M-Magnifying-Eyepiece-Digital/dp/B000C0OF54/ref=pd_cp_p_2 I could not use my manual focus lenses on my Rebel with out it. Even with the focus confirmation adapter. I am not always able to get those focus spots to light up. Perhaps too dark. Aram