I just purchased a 55-49mm and a 49mm-37mm stepdown ring. I was curious if my 55mm thread size lens on my Super-8 camera could handle a step down ring without causing vignetting.

I've never understood how useful a step down filter ring could be because the obivious downside would be the "vignetting" that is caused when a smaller sized filter is put in front of a camera lens. Vignetting can be caused by a filter or lens accessory that is attached to the front of a camera lens that obstructs part of the viewable image when viewed through the actual lens of the camera.

To my surprise, with both of the step down rings attached to my camera, the normal 55mm thread size was now being reduced from 55mm-37mm, yet I could not see any vignetting when I put the camera in the widest setting of 7mm! I didn't have a 37mm filter to fit onto the step-down filter on my camera so I don't know if I would see vignetting once a filter is attached.

However, if I want to use an inexpensive camcorder telephoto 2x telephoto extender that normally are threaded for 37mm, it looks like that could be an option worth exploring even though my camera has a 55mm thread size.

This makes me wonder if one could use smaller sized filters in general to save money. I normally buy slightly oversized filters to make sure I can stack them without vignetting and because I've heard that filters are purest closer to the center than the outer edges, but being able to put an undersized filter on a camera and save a bit of money by using a smaller size filter is something I'v never tried.

I think I have read that filters tend to be have more imperfections the farther from the center one gets, so the oversized filters would have their purpose when doing professional shoots, but if it comes down to no filter or an undersized but less costly filter, the undersized filter probably is better than not owing one at all.

Anyone have any experiences using undersized filters on their super-8 cameras?