'Handholding' a Circular Polarizer for 70-200

[Collin85]

I'm considering getting a 77mm Hoya Super Pro1 circular polarizer for my 10-22.

I'm also looking for a 67mm for my 70-200. However I know I won't be using it often on this lens (and considering that good CPLs aren't cheap), I thought perhaps I could just use the 77mm one for my 70-200 too. That is, just holding it in front of the lens when I need it for a shot. I've heard of some people doing something like this with ND grads, but what about CPLs?

Secondly, I'm one of those types who use UV filters on all my lenses, including my 70-200. Although not ideal, I was wondering what sort of degradation of IQ I should expect if I handheld a CPL in front of a lens with a UV filter already screwed on. Why would I be in this situation? Well, I would prefer not to take off the UV on the 70-200 everytime I need to handhold a CPL for just a few shots. Would be especially grateful from people who do this (and not just generalist comments from the anti-filter camp who has never tried it).

Much thanks,

[wannasmaxx]

Buy a 67-77 step up ring... shouldn't be nore than 15 bux.

[poah]

yes stepping rings are really good. use them on my 135 f2 72mm with 77mm CP

[Collin85]

Yes, I've considered a 67-77mm step up ring. But I would be most interested in the act of just hand-holding it for my 70-200. I'm mainly interested in opinions on the cons of doing it this way (such as perhaps 'filter shake' causing IQ degradation), and degradation of IQ caused by the result of having a UV filter and CPL stacked together.

[SkipD]

It is not a good idea to stack filters at all - even when they are held parallel by screwing one into the other. That's just asking for image degradation.

Your idea of handholding the filter is not one that I would recommend either. The most significant reason is that you are likely to scratch the filter when it moves around at the end of the lens. You could also induce some problems with reflections on the filter that might degrade the image.

[Collin85]

It is not a good idea to stack filters at all - even when they are held parallel by screwing one into the other. That's just asking for image degradation.

Yep, I suspected as much. I was expecting a somewhat minimal loss of IQ if I was using very high quality filters, however.

The most significant reason is that you are likely to scratch the filter when it moves around at the end of the lens. You could also induce some problems with reflections on the filter that might degrade the image.

That's pretty much what I'm afraid of (and hence leading to the 'filter shake' concern). I wouldn't expect much filter shake movement if I held the filter against the lens, although I would expect the risk of getting it scratched increased. Ergo, I began to think about actually holding the CPL away a little bit from the lens such that it was not touching the front lens rim, but it's pretty obvious that there would then be filter-lens movement.

I may try it out anyway to see how it goes. If results are poor, I'll consider a step-up ring or separate 67mm CPL.

Still looking for opinions from anyone who has actually tried this.