Quote Originally Posted by BradS View Post
see for example, the first photo posted in eBay auction #320971419969

That is a 100mm lens and the aperture scale is similar but, not quite the same...perhaps, the shutter you have originally came with a 135mm Sironar?

disclaimer: not my eBay auction...and not that of anybody I know nor is the seller anybody that I have dealt with in the past. I have absolutely no connection to the seller nor any interest in the sale.
I just did a quick search spurred by your info. That's probably it. This shutter probably originally had an old series Sironar convertible lens mounted in it. Those converted to triple their focal length losing exactly two f/stops.

Thanks, Brad!!

I haven't handled many older Sironar lenses and didn't notice the scales on the photos I've seen of them. I learn something new every day... and forget ten things.