Has anyone tried adding a filter holder to lens adapters?

BBbuilder467 wrote:

petrochemist wrote:

I've recently seen several lens adapters with built in ND filters.

Potentially useful for lenses with odd size or no filter rings..

For most lenses I can't see any advantage in having them there rather than in front of the lens,

Oh really? Try getting a filter for the front of a 800/5.6 Nikkor, then...

(yeah, I have one, it was quite expensive).

but it's prompted the thought that it might be useful for IR shots etc to have the ability to fit a filter inside some of my adapters...

Has anyone tried this?

It wouldn't be difficult to machine an existing adapter to accept a filter inside. Anyone with a lathe could do it. The problem would be finding a consistent size in filters to use.

No machining  necessary - 40.5 dia filters fit directly inside some EF-M4/3 adapters, for example. It is easiest to push a ring from a UV filter into the adapter, and then screw your filter onto that.

Useful for ND filters for video, and some other situations. Not so useful for PL filters, since it is harder to rotate them (get a Fotodiox filter for that).

Problem is remembering the filter is installed, and in which adapter

I see a few comments about "degrading IQ" and affecting focal length - both issues are overblown IME, Putting any filter on the front of a lens often reduces IQ in any case, particularly for telephoto use.

Seems reasonably likely that any adapter is being used with mirrorless, so any effect on focus is automatically corrected. No big deal.