From: "Stephen W. Ramsden" <sramsden@natca.net>
Date: June 4, 2012 12:02:41 AM MDT
To: Astro_IIDC@yahoogroups.com
Subject: Re: [Astro_IIDC] Issues taking pictures of the Sun with a PGR Scorpion
well,
If you can focus without the filter but you cannot focus with the filter, then the filter is the problem.
Stephen W. Ramsden
"Astronomy compels the soul to look upwards and leads us from this world to another"
Plato, The Republic
On Jun 3, 2012, at 8:50 PM, Rodolphe Pineau wrote:
I have a PGR Scorpion (the 1600x1200 model) and I've been trying to use it to take picture of the sun with Astro IIDC.
My problem is that I can't get a proper focus on the sun.
I'm using a ST90 with an Antares focuser, 2 2" extension tube and the PGR. The solar filter is an Identi-View from J.M.B Inc (it's an 8" filter but I built an adapter to use it with the ST90).
Here are some sample of why I get at best focus with Astro IIDC :
http://www.rti-zone.org/astro/tmp/20120603_151234_L.mov_80LN.tif
http://www.rti-zone.org/astro/tmp/20120603_151525_L.mov_80LN.tif
http://www.rti-zone.org/astro/tmp/20120603_155626_L.mov_80LN.tif
These are processed in Astro IIDC with the "Simple Solar" profile and are stack of less than 30 frame out of 700+ in each case.
I tried with other cameraa (a DFK 21F04 and a DMK 21AF04.AS) and it's the same.
As a side test I took my canon 20D, put it on the telescope, did a coarse focus (not the easiest thing using the viewfinder as this is not a Da so it doesn't have the live view for focussing) and shot a few frames. This is the best of them with minor sharpening and level in Photoshop CS4:
http://www.rti-zone.org/astro/tmp/Sun_20120603.jpg
This is a lot better than the one from the PGR.
I did some similar test with my Meade SN8 but got similar result with the PGR (and the DFK 21F04 and DMK 21AF04.AS).
http://www.rti-zone.org/astro/tmp/20120602_171454_L.mov_80LN.tif
http://www.rti-zone.org/astro/tmp/20120602_171742_L.mov_80LN.tif
http://www.rti-zone.org/astro/tmp/20120602_171921_L.mov_80LN.tif
I tried with and without a Baader Solar Continuum filter but it didn't make any difference in term of focussing and getting a crisp picture (I had to increase the exposure but all other parameters were the same).
If I point the telescope at a tree far away I can focus properly without any issues !!!
With the Venus transit in 2 days I'd like to figure this out before then .. if possible.
So if anybody has an idea of what's going on I'll be happy to hear from you !.
--
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