Re: [APML]: Color Film and Filters

[Dan Baldwin <baldwin@ixtlan.colorado.edu>]

> 
> 
>  You cannot see red through the Orion Ultra-block filter.
> >They do this. We used a red substrate on our filter to eliminate blue
> transmission.
> >It does pass IR around 850nm to 900nm, a problem for CCDs but not Tech Pan.
> >
>         I have been following this thread with great interest as I have a
> badly light polluted back yard. I also have the Skyglow and Ultrablock
> filters. Now that I can polar align for long exposures (thanks again Chuck),
> I'm trying to figure out from this discussion just what I'll be able to do
> from the relative comfort and convenience of my back yard. 
>         The Ultrablock filter is advertised as a visual filter only-not for
> photography. Are you saying it CAN be used for photography? 
>         I'm also suprised (pleasantly) to hear that the Skyglow can be used
> for color photography. 
>         I just purchased a complete darkroom setup (second hand) and am in
> the process of building a darkroom, so I'll be able to start experimenting
> (crappy weather permitting) to my little heart's content soon. I got a color
> enlarger head, but don't know color printing or processing yet. It would be
> nice to be able to do at least SOME photography from my back yard. I have
> the eyepiece filters, so there will be some aspects (prime focus, off-axis
> guided for instance) that I can't use a filter for, but if there is a chance
> I'll be able to do more with the filters, I may invest in the visual back
> filters eventually.

Hi Mike---

        Thought I would save you the extra expense that I paid out. Dont buy the visual 
back filters, buy the 48mm size instead--This way you can put a filter downstream
of any off axis guiding device and you wont be reducing the brightness of guide stars--
I bought a Lumicon DS filter for the back of my C11, cost was $119--By the time
I figured out I needed the 48mm size, the price had gone up to $199 !!!

Dan Baldwin





>         Hope you all have better weather than I'm getting. Cold front is
> going through now, I think. Maybe in a couple of days...
> 
>