Ok, so I appreciate that this is maybe just a little too much of a niche question, but I know we have a huge amount of experience on this here forum, so I thought I'd put it out there just on the off-chance...
I want to get an #87 Infrared filter for my Mamiya 300mm f/2.8. This lens has a drop-in filter at the back, and comes with a set of glass filters, and a holder for gelatin.
The glass filters screw into the filter holder - quite amazing actually that they provide holders for every filter that ships with the lens, so you'd never actually have to unscrew them, unless that is you wanted to use an alternative.
I've measured the thread on one of these glass filters, and it was 45.9mm.
Now it turns out that Heliopan make 46mm glass IR filters -
Infrared #87 | B&H Photo Video
Does anyone know whether, or have experience of, 46mm screw in Heliopan filters fitting the Mamiya filter holder?
Obviously I could go the easy route and just get a gelatin filter cut down to the required 43.5mm size for the gelatin filter holder, but I'd prefer to go glass if at all possible.
Thanks in advance, and kind regards!