Brand New to the market are these adjustable diopter / viewfinder magnifier for Fuji XPro 1, Fuji GF670, Epson RD1
This version is the later type Y which has a magnification range from 1.15x to 1.65x or equal to -150 to +350 diopter
We have heard great reviews on this product, whether you have young or mature eyes, glasses wearer or non wearer - it basically can suit all
Supplied in retail box, rubber eye piece and even a cleaning cloth
It is from the same manufacture that produces the popular Leica M series version - hence the M review:
Review made by a user from Leica Magazine:
"I am using the Bresson magnifier for critical focus. Once the diopter is adjusted for my eyes it works wonderfully. So far I have not had any problem with the diopter adjustment moving while the magnifier is on the camera. Certainly, removing it will cause it to move and it needs readjustment when put back on.
I have found it most useful when working with very fast lenses wide open and when using my 135mm lens. In both cases the reduction in field of view is not a problem for me. I have not noticed any reduction in contrast and, as long as I keep it clean, it is easy to see through. Finally, I wear glasses and use the eyecup. I actually like it.
The biggest downside for me is that it disrupts the clean lines of the rangefinder. But when I am doing sports work with the 135 and 90 it is so handy that the size of the protrusion off the camera back really becomes a non-issue.
Overall I am quite happy with the Bresson Magnifier and it works perfectly for those circumstances where I use it. Of course YMMV but, if your eyes are aging, I think it is worth a try anyway"