At 8/1/2009, you wrote:
I don't think the extender does any magnification. In fact, it reduces the magnification. On a full frame camera that is no big deal. On a crop format camera it is. It is hard enough to see the viewfinder as is, but by reducing it even further, I would think it would make it much harder to focus. My friend with the 5Dm2 has one. It lets him see the full frame with his glasses. As I stated previously, when he tried my Nikon magnifier, he could not see the full frame with his glasses. I did not try his extender on my Rebel.Read the reviews at: <http://www.amazon.com/Canon-EP-EX15-Eyepiece-Extender-Cameras/dp/B0000AQI9E>http://www.amazon.com/Canon-EP-EX15-Eyepiece-Extender-Cameras/dp/B0000AQI9ELook around on Google. The purpose is for eyeglass users to see the whole viewfinder. It reduces the image by 30%, so if you are looking for a focusing aid, this is not what you want.
I agree with Aram. The Canon unit is for helping eyeglass users see the entire frame. The Nikon unit is a magnifier, to aid in critical focusing.
With the Nikon magnifier, I could not see the entire R8 frame while wearing my glasses, but could see it all, just fine, without 'em I adjusted the diopter control, and focusing was perfect, without glasses and I could see the entire frame, to boot!
If you want to improve manual focus with your Leica Glass, try the Nikon DK-21M... not a big loss, if it doesn't work for you ... and a heckuva bargain if it does!
Cheers! --- David Young Logan Lake, BC Wildlife Photos: www.furnfeather.net Rodeo Photos: www.galleries.furnfeather.net Personal Website: www.main.furnfeather.net