Step up rings?

[MediaMagic]

I've never used a step up or down adapter for filters on a lens. I have a pretty extensive filter collection in 72mm I need to step to 77mm for the new lens.

It doesn't seem that large of a difference but I'm sure the adapter will change the position/distance of the filter a minute amount from the front glass. And there will be 2MM difference around the outer edge.

I'll just buy a new UV and CP filter in 77mm but for many of the others, I'd like to try using what I already have.

What aberrations can I expect if I try stepping up? and are there work arounds?

David

[abwhitt]

Hi, I don't really know a lot about it, but I understand it is better to step up than down. Having said that, I have ordered a step down ring, awaiting delivery. I asked a similar question in another newsgroup and everyone seems to get good results, even on a big stepdown. Bear in mind, that with the 1.6 ratio of the 10D you shouldn't even have to crop. Or so I've been told, we'll see!
Regards
Frank

[Roger_Cavanagh]

I don't think you need worry about the small change in filter distance from the lens, but you'll just have to see whether the smaller FOV avoids the vignetting that you would get on a 35mm film camera caused by the stepdown ring.

Regards,

[CyberDyneSystems]

That step down ring is sooo uch cheaper,. it is certainly wort a try. This is an aspect where I never would have considered the 1.6 crop factor (duh!!!)

I wonder,.. If the step down ring only ends up covering up parts of the lens that are not actually in use do to the 1.6 crop factor,. then in fact the step down ring can help improve your images in another way,.. it will block direct light from hitting the parts of the lens not in use,. aiding the image quality like a good lens hood.

Now I wonder if how much of the 86mm filter I would actually need on my 50-500mm lens. especially at the long end? Do you know how much a decent 86mm polarizer is?

I'm off to B&H to try a step down ring! :D

[robertwgross]

CyberDyneSystems wrote:
...
Now I wonder if how much of the 86mm filter I would actually need on my 50-500mm lens. especially at the long end? Do you know how much a decent 86mm polarizer is?


I had to pay about $150 for a circular polarizer in that size.

Just try to buy rectangular Cokin filters for it!

---Bob Gross---

[abwhitt]

CyberDyneSystems wrote:
That step down ring is sooo uch cheaper,. it is certainly wort a try. This is an aspect where I never would have considered the 1.6 crop factor (duh!!!)

I wonder,.. If the step down ring only ends up covering up parts of the lens that are not actually in use do to the 1.6 crop factor,.


This is the point that was made to me. I can't find the thread now, but somone assured they they use quite a large step down ring, something like seventy something down to fifty something, with no ill effects. I am waiting for a 67-58 step down, I'll let you know how I get on when it arrives.