From: Rodolphe Pineau <pineau@rti-zone.org>

Date: June 3, 2012 6:50:40 PM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Issues taking pictures of the Sun with a PGR Scorpion

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 !.

--

|        Rodolphe Pineau    RTI-Zone        |

|         http://www.rti-zone.org/          |

|   Robotics / Unix / Mac OS X / Astronomy  |