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FORUMS Photo Sharing & Visual Enjoyment Astronomy & Celestial 
Thread started 07 Dec 2008 (Sunday) 10:02
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1st Attempt with Tracking (CG-5)

 
renderwerks
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Dec 07, 2008 10:02 |  #1

After a few rounds of un-aligned observing, I finally had a chance to attempt a polar alignment and try a few exposures. I shot with a 40D at ISO 800 through a Sigma 70-200 2.8 APO at about 100mm, f/4.0. I figured this would be a pretty forgiving focal length for a first try...

Multiple exposures stacked in Deep Sky Stacker and processed in CS3. I've got a lot to learn about processing, but I thought I'd offer these up for critique as first efforts.

Polar alignment was performed through my 500mm scope with a 20mm eyepiece (25x). I just "eyeballed" Polaris in the FOV then mounted my camera/lens; It's off a bit as I have egg shaped stars:

IMAGE: http://farm4.static.flickr.com/3117/3086414751_a3234e8557_o.jpg
Pleiades; 4x120sec + darks + bias frames.
IMAGE: http://farm4.static.flickr.com/3090/3087247392_7ea37d7ac7_o.jpg
Milky Way, Deneb in center, Sadr in lower left. 6x90sec + darks + bias frames.
IMAGE: http://farm4.static.flickr.com/3080/3086412927_77624e51af_o.jpg
Milky Way near Cassiopeia. Left side of image is roughly NorthEast. 4x120sec + darks + bias frames.

Rick-
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strgazr27
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Dec 07, 2008 10:15 |  #2

Rick,

A real nice first effort. As far as polar aligning a mount without a polarscope, the most dependable way is to drift align it. It should only take about 30 minutes and at the Fl's your imaging at should allow for some pretty nice 2-5 minute exposures depending on where in the sky your shooting.

You will also see a benefit from shooting flat field frames with a lens. Take a white t-shirt and double it up. Place it over the lens and set the camera to AV mode at ISO 100 and click off about 10 of them. They truly make a difference in how far you can stretch an image. You also want to make sure you don't clip the black points of your images. The black background does help to hide noise but hides faint detail and at a certain point the images look "Fake" or "Plasticy" Lol if that were a word.

Drop me PM if you ever need any help.

Keep it up!

CS's


Gripped 40D - 17-40L - 70-200 f/4L - Gitzo GT0531 Mountaineer - Astrotrac TT320X-AG
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Sorarse
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Dec 07, 2008 12:08 |  #3

I haven't tried tracking astrophotography yet, but if my first efforts come out anywhere near those, I will be very happy.


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Nighthound
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Dec 07, 2008 15:12 |  #4

You're off to a good start Rick. Did you first roughly align using the built in polar scope in the cg-5 and then perform a drift align using the 500mm scope? From your description it sounds like you simply pointed north(polaris) and then started shooting.

Before aligning did you first set your mount's latitude? Unlock the latitude adjustment screws on the sides of the mount and adjust the latitude setting to your location (34N, I believe).


Steve
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renderwerks
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Dec 07, 2008 18:06 |  #5

strgazr27 wrote in post #6829851 (external link)
Rick,

A real nice first effort. As far as polar aligning a mount without a polarscope, the most dependable way is to drift align it. It should only take about 30 minutes and at the Fl's your imaging at should allow for some pretty nice 2-5 minute exposures depending on where in the sky your shooting.

You will also see a benefit from shooting flat field frames with a lens. Take a white t-shirt and double it up. Place it over the lens and set the camera to AV mode at ISO 100 and click off about 10 of them. They truly make a difference in how far you can stretch an image. You also want to make sure you don't clip the black points of your images. The black background does help to hide noise but hides faint detail and at a certain point the images look "Fake" or "Plasticy" Lol if that were a word.

Drop me PM if you ever need any help.

Keep it up!

CS's

Thanks Bobby. I need to read up on how to drift align. I'm also going to get a polar scope. First, I want to look into either getting an illuminated one or a way to modify the non-illuminated one sold for the CG5. I have an illuminated Orion 8x40 finder, but was waiting on the mount when I tried this imaging.

I'll have to try shooting flats as well. As far as processing, I tried to follow the advice on naturescapes.net (external link). Plus, I just loaded everything into Deep Sky Stacker and let 'er rip! I haven't tried adjusting the settings as of yet.

Thanks for the advice, I appreciate it. I'm pleased with these first results, and it has spured my appetite for more practice. :D

Sorarse wrote in post #6830381 (external link)
I haven't tried tracking astrophotography yet, but if my first efforts come out anywhere near those, I will be very happy.

Thank you very much; it was kind of scary wondering if I was doing anything right. I felt better when I got a look at the images.

Nighthound wrote in post #6831393 (external link)
You're off to a good start Rick. Did you first roughly align using the built in polar scope in the cg-5 and then perform a drift align using the 500mm scope? From your description it sounds like you simply pointed north(polaris) and then started shooting.

Before aligning did you first set your mount's latitude? Unlock the latitude adjustment screws on the sides of the mount and adjust the latitude setting to your location (34N, I believe).

Thanks Steve. As stated above, the polar scope is optional on the CG5. I've looked at one, but it looks kinda "cheap". I'm investigating options. I may have to adapt or make something.

What I did was set up my tripod with the RA axis pointing roughly North, got the tripod leveled, then I mounted and balanced my 500mm refractor with an eyepiece and adjusted my latitude and fine North adjustments until Polaris was in the center of the view to the best of my ability. I had no crosshairs, so I got as close as I could. I then removed the refractor and replaced it with my camera/lens and pointed it to my target. I used a laptop and liveview to focus and count off the exposure length. Next on the agenda is reading up on and learning how to drift align.

I appreciate and welcome your advice. Thank you for taking the time here to help us newbies!

I've got quite a list of things that I need to purchase to help me out. Battery packs, red lights, red shield for my laptop, etc... Right now, I'm real bare bones. But I think I'll gain more in depth knowledge if I start this way and add equipment as my knowledge grows.


Rick-
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Sorarse
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Dec 07, 2008 18:21 |  #6

Rick, have a look at this guys website. He has a section on there where he explains in very simple terms about drift alignment. Well I understood it, so it must be simple ;)

There is also a simulator on there that allows you to practice.

Drift aligning tutorial and simulator (external link)


At the beginning of time there was absolutely nothing. And then it exploded! Terry Pratchett

http://www.scarecrowim​ages.com (external link)
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renderwerks
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Dec 07, 2008 18:24 |  #7

Thanks for the link. That's one of the things I love about this forum; the willingness of members to help one another improve!


Rick-
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1st Attempt with Tracking (CG-5)
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