RE: [APML] 48 mm filter

Don,

Thanks for the reply. I thought the Hoya R60 filter would work OK, but I was concerned about the thread diameter of the filter. The girl I spoke with at Edmund wasn’t sure it would work with the adapter. Their thread size was listed at 49mm with a pitch of .75mm.

That gave an OD of 51mm, I think that is a mm to big on both accounts.

Scott

-----Original Message-----
From: owner-astro-photo@seds.org [mailto:owner-astro-photo@seds.org] On Behalf Of westergren
Sent: Tuesday, January 14, 2003 9:32 PM
To: astro-photo@seds.org
Subject: Re: [APML] 48 mm filter

Scott,

I use one of the Edmund red filters with Tech Pan. It really gives a nice contrast image of the NA nebula. It is not narrow band, but I don't think it has to be to work for these types of astrophotos. Most of the skyglow and light pollution is in the yellow to green parts of the spectrum, below the 600 nm cutoff of this filter. I found that exposure through the filter of a red nebula didn't attenuate the image of the nebula noticeably. It just made the sky (the non-nebula) really dark. The filter does affect focus slightly, so I checked the focus in daylight with and without the filter, measuring the focus with a dial vernier. It shifts about .010 to .012 inch on my FSQ106 (further out with the filter).

The Edmund filter won't allow Sun pictures. I can't think of a reason to need a narrow H-alpha filter for deep sky photos.

Don

----- Original Message -----

From: Scott Hammonds

To: astro-photo@seds.org

Sent: Tuesday, January 14, 2003 03:42

Subject: [APML] 48 mm filter

Hey list,

I’m looking for a 48 mm Ha filter to fit my 35mm camera adapter. The adapter is made by Astro-Physics and accepts 48mm filters.

I was looking at Edmund Optics. http://www.edmundoptics.com/IOD/DisplayProduct.cfm?productid=2079

I don’t think any of these will work, but I wanted a second opinion. Any one with experience with these filters?

Thanks,

Scott Hammonds