Re: [APML]: M20 through DeepSky

["Andrea Ricciardi" <mc7624@mclink.it>]

 ----
From: Philip Perkins <philip@astrocruise.com>
To: astro-photo@nightsky.com
Date: Thursday, August 28, 1997 5:30 AM
Subject: [APML]: M20 through DeepSky

>
>Howard Anderson and Steve Bell expressed an interest in seeing comparison
>photos of M20 with and without a Lumicon Deep Sky filter. I have posted a
>second image of M20 on my web page, taken with the DS filter. Please
click
>on the M20 thumbnail ...
>
>http://www.astrocruise.com
>
>Conditions for the two exposures were so similar that I would consider
this
>a valid direct comparison - full details on the web page. The differences
>are quite striking - I noticed:
>- amount of blue response
>- colour balance (esp the red of M20)
>- number of stars recorded
>
>You may even prefer the second image of M20 - please let me know...
>
>Thanks  --Philip
>

Wonderful shots, Philip,
obviously better the first one, but using a deep-sky filter enable you to
have a longer exposure than without it, and still obtain the same sky
density: I've found that under good skys I can run 1.5-2 times longer:
maybe you should try with a longer exposure to find what the filter can
show.

Andrea.