Goerz Dagor 8 1/2" filter thread?

[Matt_1193]

This may sound stupid to some of you, but does anyone know what the filter threa d is for this lens? I measured what I thought was 40mm, so natch - I think 40.5 mm right? No. A 40.5 seems to want to be the right size, but it will not thread on. So I assume (there I go again!) that it must be 39mm, and purchase my filter in 39mm. Wrong again. But I have never seen a 40mm filter. Does anyone know for a fact what it is? Any 240 Dagor owners?......

[Hans Berkhout]

I faced the same frustration years ago. Finally had a step-up ring custom-made by machinist, to 55 mm. My wide angle took an over the counter step-up to 55 mm and my 360 Artar takes 55 mm. So the cost for the custom made item is offset by the economics of one filtersize for all.

[Steve Grimes.]

These American made lenses do not take any ordinary metric size filters. Its best to have an adpater made (either slip over or screw in) to convert the lens to a standard Metric size, probably 49mm in this case. See: http://www.skgrimes.com/slipon/index.htm for info about the kind I make.

[M.]

Are you sure that it's an 8.5, and not an 8.25 lens? Anyhow, mine takes an 1 11/16" slip-on adapter for series VI.