Ill bet the problem is the objective (front) element isn't big enough. When I used my Sony DSC 700 several years ago I found I had to go to the Olympus E1 adapter because it was the only one with a rear opening that fit the 62mm scew-in mount but I was saddled with a very heavy (and expensive) add-on and whose magnification factor was only .8 - but it worked well with no vignetting. The bonus was I could fit it on my Maxxum 24-85 lens as well where there was some vignetting