Front thread size for Century Lenses
 

Can someone please confirm for me the FRONT filter thread sizes on the following Century Optics lenses for the GL2:

0.55x Wide Angle Adapter - Stock Code: DS-55WA-GL

0.65x Wide Angle Convertor - Stock Code: DS-65CV-GL

2x Tele-Convertor - Stock Code: DS-20TC-GL

The Century Optics site doesnt have this information in their specs for these lenses for some reason.

My assumption is that the .55x is 72mm since they list the outer diameter as 75mm, and the .65x and 2x Tele are 77mm since the outer diameter is 80mm

Am I correct?

Also wondering the diameter
 

Well I too am puzzled. I actually tried to fit a 77mm filter on the 2x teleconverter and it seemed to small, so my guess is the actual thread size is 80mm. However I have searched extensively for filters that are 80mm in diameter, and found nothing. Anybody have any advice.

For added information in my case I'm trying to add a polarizer on the front of the 2x teleconverter.

Try Try again
 

I just thought id ask again in case it slipped by somebody who has the answer. Id really like to put a Polarizer on my doubler, but i cant figure out if anybody has threaded a filter onto the doubler before. Im pretty sure it is 80, but cant find any 80mm filters.

Thanks