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Wanted: Neutral Density filters, 1" unmounted and 24mm mounted

Posted: Sun May 14, 2017 6:01 am
by twhite
I am modifying and modernizing an older Japanese-made Herschel wedge that I have and am interested in finding neutral density filters to use with it in older scopes. The wedge was made for the Japanese 24mm/0.965" standard, so it's kind of hard to find proper-sized filters now. It's still fun to use the old classics every now and again.

I've tried using a 0.965-1..25" step-up adapter, but this adds both too much length and too much weight on the wedge when using 1.25" eyepieces, even light ones.

So, ideally I'm looking for two things:

1) a 1" (or so) ND 3.0 (0.1% transmission) or so (more is better) UNMOUNTED filter which I can adapt to mount permanently in the wedge. A filter in a damaged 1.25" holder *might* work.

2) a range of ND filters in 24mm filter holders, a la Baader -- "true" ND 0.6, 0.9, 1.8 and 3.0 filters. Even one or two would be better than none. A typical Moon filter is 15% transmission and 0.6 is 25% transmission, so higher numbers are more desirable to me.

If you can help me out, PM me. I'm not in a huge rush to do this, but it is one of those little projects I'd like to get done someday.