Odd part needs identifying.

[David Hughes]

Hi,

I bought this in a charity shop because it came with a Hoya UV 40.5mm filter but what is it? The other side is flat with 40.5MM printed on it and in all it's just under 2½ inches in diameter.

Regards, David

 

[ronnies]

Is it an adapter for the Cokin square filter system?

Ronnie

 

[sevo]

Adapter for some filter or compendium holder system - there have been many mutually incompatible ones around. The small Cokin holders were immensely popular among 1980s amateurs, but if it comes from a (former) pro, it is more likely to be a adapter for a 75mm gel holder.

 

[oltimer]

That's the right size for Cokin A series. My Cokin P is another inch wider. Dave I believe that adapter fits one of my 50mm early Canon screw mount lenses.

 

[David Hughes]

Thanks everyone.

It makes sense as I've never bothered with filters (but like to have them for when I sell cameras). What baffled me was why anyone would want to screw a metal plate into the filter thread...

Thanks again. Regards, David

 

[David Hughes]

Just a thought, that thing is no use to me, so if anyone in the UK wants it, just ask.

Regards, David

 

[LukasB]

Just to chime in another theory I bought a Ring Light from Amazon a few Years ago... it looks very similar to the filter attachment for the Main Unit that would hook onto the extended collar. (There were a number of different sizes included from 49mm - 72mm if I'm recalling correctly.) I imagine the same system in which the Cokin filters work, though I have very little experience with them.