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guyroch
sage
Reged: 01/22/08
Posts: 254
Loc: Ottawa, Canada
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Hi folks,
It’s been 29 days straight since we had clear skies in my neck of the wood and for some reason (yoopee) 2 days after my SSAG arrived… boom… one clear night, the event took place October 25th 
Anyways, here is what I was able to accomplish the first night out with the SSAG autoguider. This is 3 frames of 6 minutes each, 5 darks, 25 flats, ISO 800. All images acquired with Nebulosity and guided with PHD. Image lightly processed in Nebulosity with DDP applied. Imaging scope is an entry level 6” reflector f/5 mounted on a celestron CG5-GT. Guide scope was the Orion 80mm short tube at f/5.
Towards the end of the night though, the guiding was not so good, I wasted a good 2 hours and had star trails in every frame after the above 3 were taken. The weight of the guide scope and SSAG (4lbs combined) pushed the limit on my available counter weight though, it was a bit out off balance and I can only assume that as the OTA was slowly moving the one side, the counter weight became more and more of an issue as the night went by. Would this really mess things up to the point were one would lose 2 hours of light frames?
Thanks for looking, and I’m always open to constructive criticism.
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Skywatcher 750mm 6" Reflector f/5
Celestron CG5-GT mount
Orion ST80 + SSAG autoguider + PHD
Canon 40D (unmod) + TC-80N3 remote timer
Astronomik CLS clip filter
Orion SkyGlow light polution filter
Orion AccuFocus + homemade Bahtinov mask
Bushnell 8x42 h2o® Waterproof Binoculars
Sky Atlas 2000.0 Field Version (Laminated)
Plenty of patience and a wife that doesn’t quite understand my love for clear skies, but let’s me go out anyway ~ thanks honey bunny 
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Nils_Lars
Post Laureate
Reged: 01/04/08
Posts: 3410
Loc: Santa Cruz Mountains , CA
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Looks like you pulled a lot of nebulosity out of those 3 frames and your 6 min subs look really good for all the weight you have one there.
Ya unfourtunatly balance can be a bigger issue then guiding if it was off.
Framing is maybe a bit off but thats a tough one to fit in your scope so I cant fault you for that.
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Erik
Orion Atlas Self Hypertuned (EQMOD)
Orion ED 80
Williams Optics VII reducer
Celestron 8" SCT
Orion Starshoot Autoguider
PHD guide
Canon 400D Hap Griffin Mod w/Baader filter
Astronomik clip-in LP filter and 12nm Ha
Stilleto CVF and Bahtinov mask
Tamron 75-300mm&28-80mm lenses
NexImage webcam
http://www.flickr.com/photos/31986095@N05/
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Buhlig
super member
Reged: 12/03/07
Posts: 192
Loc: Derby, KS
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CG-5 are pretty finicky about balance and load it heavy east so it's always driving against some weight. Also, if you are very close to polar alignment, DEC commands that switch (n, s, n, s etc) result is poor imaging as that invokes your backlash (as will e/w switching with incorrect balance). So, I used to purposefully misalign ever so slightly so that the commands were largely one directly in both RA and DEC. You'll pay a field rotation penalty for it though, but Neb can take alot of that out in alignment.
Sean
P.S. Nice image too...more subs and you'll love the results.
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Celestron 80mm ED Apochromatic Refractor
Orion 8" Newt
Celestron 80ST achro (guider)
PHD via handcontroller interface
CG-5 Advanced GT Mount
Canon 350D
Philips SPC900NC
http://www.flickr.com/photos/derbysluggers/sets/72157605255114566/
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guyroch
sage
Reged: 01/22/08
Posts: 254
Loc: Ottawa, Canada
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Quote:
CG-5 are pretty finicky about balance and load it heavy east so it's always driving against some weight. Also, if you are very close to polar alignment, DEC commands that switch (n, s, n, s etc) result is poor imaging as that invokes your backlash (as will e/w switching with incorrect balance). So, I used to purposely misalign ever so slightly so that the commands were largely one directly in both RA and DEC. You'll pay a field rotation penalty for it though, but Neb can take alot of that out in alignment.
Interesting concept of purposefully misaligning the mount ever so slightly.
As for the DEC switching though, PHD has a setting that you can set to resist switching on DEC and it's currently turned on in my setup. Is this what you meant?
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Skywatcher 750mm 6" Reflector f/5
Celestron CG5-GT mount
Orion ST80 + SSAG autoguider + PHD
Canon 40D (unmod) + TC-80N3 remote timer
Astronomik CLS clip filter
Orion SkyGlow light polution filter
Orion AccuFocus + homemade Bahtinov mask
Bushnell 8x42 h2o® Waterproof Binoculars
Sky Atlas 2000.0 Field Version (Laminated)
Plenty of patience and a wife that doesn’t quite understand my love for clear skies, but let’s me go out anyway ~ thanks honey bunny
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s58y
Postmaster
Reged: 12/12/04
Posts: 5498
Loc: Eastern NY
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Nice image, for just 18 minutes of total exposure.
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Hutech 30D, SBIG ST-402 autoguider
SV80S, TV102iis
Old camera lenses: 800mm f/5.6, 180mm f/3.4
AP900, Barndoor tracker
http://www.pbase.com/s58y
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guyroch
sage
Reged: 01/22/08
Posts: 254
Loc: Ottawa, Canada
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Thanks s58y. Can't wait for the clouds to break out and give a second try. For now, I'm optimizing my time and building a dark library of 3, 4, 5, 6, and 10 minutes at ISO800 and 1600. I have a small heated outdoor workshop which I can control temperature so I'll be able to take them in 10c increment from -20c to +30c.
--------------------
Skywatcher 750mm 6" Reflector f/5
Celestron CG5-GT mount
Orion ST80 + SSAG autoguider + PHD
Canon 40D (unmod) + TC-80N3 remote timer
Astronomik CLS clip filter
Orion SkyGlow light polution filter
Orion AccuFocus + homemade Bahtinov mask
Bushnell 8x42 h2o® Waterproof Binoculars
Sky Atlas 2000.0 Field Version (Laminated)
Plenty of patience and a wife that doesn’t quite understand my love for clear skies, but let’s me go out anyway ~ thanks honey bunny
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Buhlig
super member
Reged: 12/03/07
Posts: 192
Loc: Derby, KS
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Quote:
As for the DEC switching though, PHD has a setting that you can set to resist switching on DEC and it's currently turned on in my setup. Is this what you meant?
Yeah, you definitely want that. I don't know the details on that function, but even with that set, it still can't "resist" is certain situations. I never found it reliable until I forced the mount into a slight misalignment. I even went so far as to guide in DEC in only one direction. That definitely will take care of backlash issues (but better make sure the star drifts the direction you want!)
I had alot of issues with DEC backlash...so I spent alot of time experimenting with alot of different things...many nights, many trashed subs, many cold fingers, etc. When I finally got a system/setup that worked, I upgraded...go figure. But the best was to 1) keep the weight against all the PHD commands...both in DEC and RA. 2) Misalign the mount ever so slightly such that commands are issued mostly in one direction (again, both RA/DEC and it takes some real time monitoring of PHD) and 3) guide in DEC in only one direction. Those 3 things should give you 80-90% successful subs...it does take awhile to get the knack and it's sky location dependent (i.e. where you plan to shoot)...but pretty easy to learn.
Sean
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Celestron 80mm ED Apochromatic Refractor
Orion 8" Newt
Celestron 80ST achro (guider)
PHD via handcontroller interface
CG-5 Advanced GT Mount
Canon 350D
Philips SPC900NC
http://www.flickr.com/photos/derbysluggers/sets/72157605255114566/
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