Unguided exposures: Pushing the limits
A guy on one of the other email lists I'm on posted a question about how long an exposure one can make without guiding. That sounded like a challenge... :) I've posted some of my test images to the UA gallery. All shot with the C-14 at f/11 which equates to about a 4,000mm focal length (hence the tiny field of view). http://gallery.utahastronomy.com/main.php?g2_itemId=10620&g2_page=1 Up through 6 or 7 minutes looks ok but there is just a touch of elongation in the stars in the longer exposures. I'm not too bothered by that though since I seldom go over 5 minute without guiding. Ok, so now that I've got the polar alignment worked out maybe Tyler can show me how to take pretty pictures. Carpe Noctem! patrick p.s. For those new to the UA Gallery, you do not need to register in order to look at the pictures (more than a few have thought registering is necessary).
This reminded me of stories of the old days with the 100" on Mt. Wilson, and 200" on Mt. Palomar. Photographic emulsions were notoriously slow back then; so much so that some exposures required several nights of continuous tracking to build up an image on the plate. Spectrums of distant galaxies were the worst offenders since an already feeble source had to have it's light spread-out over a larger area. An exposure was begun as soon as the target was high enough for good seeing, and ended when it had descended in the west to the point just before compromised seeing. The dark slide was replaced on the plate, and it was secured until the next night, when the field was re-aquired and the exposure started up again with the same piece of film. I'm sure that the Wilson and Palomar drives were made as precise as was humanly possible, but astrophotography still required hand-correction and guiding by eye. Imagine yourself having to stare at the same guide star for hour after hour, night after night! You begin to understand Milton Humason's pile of empty liquor bottles in the bushes outside Palomar... the radio was surely playing loudly in the dome those nights. And no bellyaching by modern amateurs allowed! ;o) On Tue, Apr 15, 2008 at 5:29 AM, Patrick Wiggins <paw@wirelessbeehive.com> wrote:
A guy on one of the other email lists I'm on posted a question about how long an exposure one can make without guiding.
Patrick, That mount is incredible. Nice comparison images to demonstrate what is possible. I am amazed that the mount is that good, especially given the focal length. I would love a chance to image with you sometime. I just need a clear night and an invitation (hint, hint). :) Cheers, Tyler _____________________________________________ -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Patrick Wiggins Sent: Tuesday, April 15, 2008 5:29 AM To: utah astronomy listserve utah astronomy Subject: [Utah-astronomy] Unguided exposures: Pushing the limits A guy on one of the other email lists I'm on posted a question about how long an exposure one can make without guiding. That sounded like a challenge... :) I've posted some of my test images to the UA gallery. All shot with the C-14 at f/11 which equates to about a 4,000mm focal length (hence the tiny field of view). http://gallery.utahastronomy.com/main.php?g2_itemId=10620&g2_page=1 Up through 6 or 7 minutes looks ok but there is just a touch of elongation in the stars in the longer exposures. I'm not too bothered by that though since I seldom go over 5 minute without guiding. Ok, so now that I've got the polar alignment worked out maybe Tyler can show me how to take pretty pictures. Carpe Noctem! patrick p.s. For those new to the UA Gallery, you do not need to register in order to look at the pictures (more than a few have thought registering is necessary). _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com
Hi Tyler, On 15 Apr 2008, at 18:17, Tyler Allred wrote:
That mount is incredible. Nice comparison images to demonstrate what is possible. I am amazed that the mount is that good, especially given the focal length.
Thanks.
I would love a chance to image with you sometime. I just need a clear night and an invitation (hint, hint). :)
Sure. Just let me know what you'd like shot and I'll get you lots of data. Cheers, patrick
participants (3)
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Chuck Hards -
Patrick Wiggins -
Tyler Allred