Step Down Ring

I have a lens with a 77mm thread diameter but have a 72mm Heliopan filter that I'd like to use. If I get a 77mm-->72mm step down ring will I run into any image issues? Vignetting, shadows, or anything of that nature? Thanks!

Maybe. It depends on what lens you are using. Some lenses have bigger filter diameters than necessary, then it will works with a step down.

For tele lenses it is pretty easy. If the entrance pupill is bigger than 72mm, you will run into some trouble. But most likely you can fix it with just stopping down.

For wide angle, stopping down will not allways fix this type og vignetting, mayby it will just sharpen the vignetting edge. But maybe you can find it usable with just some croping.

Anyway, a step down ring is not that expensive. Go get the ring, and try for your self with your own lens.

You will have problems, buy a larger filter. Never use a ring to step DOWN, always step UP.

ralff wrote in post #16187706
You will have problems, buy a larger filter. Never use a ring to step DOWN, always step UP.

Not necessarily; it depends on the lens. Some will vignette in this situation, others won't.

The lens is a Canon 24-70mm.

effstop wrote in post #16187918
The lens is a Canon 24-70mm.

Is your 1DII 1.3 crop, or full frame (I don't remember). If it's the crop, you'll probably be fine. FF might vignette a bit, especially at the wide end.

Try Adorama.

They have several step up and step down ring sizes available.

When buying step up/step down rings, be VERY CAREFUL reading the description before you click 'add to cart'. Look specifically for wording like 'use smaller filter on larger diameter screw ring' or something like that.

Depending on the manufacturer (I think), some use the term 'step down' to reference a smaller filter in a bigger screw in ring, and others use 'step down' to mean a too-large filter to a smaller size lens screw ring. I have several 'step down' sizes to put 82mm filters on lenses with 67, 72 and 77mm filter size threads and almost bought the wrong 'direction' rings.

Again, read the description carefully, and, if possible, enlarge the picture(s) to make sure it has the threads where they should be!

So, the 1D MKII is a 1.3 crop so I shouldn't run into any vignetting right?