7 replies to this topic

[DEnc]

Could someone point out commercial sources for ND filters?  I haven't found the right terms for a web search, apparently--I'm only finding filters for planetary imaging.

 

I'm hoping for about 25% transmittance in front of JC B and V filters,based on exposures I've done with RGB filters.  Presently I'm looking at several filter drawers to thread into my imaging system, so the dimensions and mounting of the ND filters are flexible at the moment.

 

Thanks.

 

 

[leveye]

Amazon.com?

[Jim Davis]

Is this what you are looking for: http://www.telescope...c/48/p/5598.uts

[GlennLeDrew]

If used near to the focus, optical quality need not be superb. ND filters in the opacity range desired are (or at least used to be) offered for camera lenses. And they are (or were) commonly mounted in cells having thread diameters from 49mm to 72mm.

[DEnc]

Thanks, found options at Edmund Sci.

[Tim Hager]

Wouldn't stopping down the telescope aperture be an alternative for you?

[DEnc]

Re: aperture stop, why, yes it would!  Richard Berry over on the AIP4WIN-photometry forum suggested the same, and I've been working on it.  It's a great alternative.

 

Thanks.

[Tim Hager]

Less expensive too!