Astrophoto! Messier 27 -- Dumbell Nebula

[h2olawyer]

Well, it's been a long & winding road to get to this point, but I finally have a decent widefield photo to share.  I took it Wednesday night / Thursday morning.  The image is composed of 11 separate exposures of 3 minutes each, stacked & aligned with a master dark frame subtracted to eliminate camera noise.  Then the resulting image is stretched and the background color is compensated.  A nifty piece of software called Nebulosity helps with both image capture and processing.

I was mainly out to get the autoguide system working better.  I was able to get some 5 minute exposures, but only 3 of the 5 were usable.  (none used in the image below)  The rejects had some jumpiness (double image) or elongated stars.  Some of the problem was the Polar Alignment was a hair off & the scope could have been a little better balanced.  Man, there is a ton to learn in this hobby!

For those who are interested, here are the full details -
Telescope:  Celestron C8N-GT (8 inch diameter Newtonian on the AS-GT mount & tripod)
Scope focal length: 1000mm
Scope Diameter: 203mm
Focal Ratio: f4.9

Camera: Unmodified Canon 450D XSi with "T" ring and 2 inch adapter to connect directly to focuser - no eyepiece in the optical train
Exposure Setting: 3 minutes @ ISO1600

Location: Middle of Ft. Collins, Colorado  July 15, 2009  Temp: 65F.

Guide Scope: KWIQ Guider - QHY guide camera adapted to a modified 9x50mm finderscope, run through PHD Guiding software (Push Here Dummy)

Don't hesitate to ask any questions!

H₂O

[funkamongus]

yeah!!!!! NICE! The H2ubble...

[h2olawyer]

Still have a long ways to go, but thanks!  This is really the first astrophoto I'm kind of proud of.  Below is an earlier attempt of Messier 13, taken on May 19th.  I have learned a bit about processing and focusing since I took this one.  With all the rain we had through June, I spent many hours just playing with older images.  This one is shown as I processed it back in May.  I darkened the background too much (losing some data) and the 90 second exposures were just a bit too short.  It is a bright object - visible as a smudge to the naked eye under dark skies.

H₂O

[Kojo]

Wow, those are both great pictures. It's very difficult to take long exposure pictures like that due to the Earth's rotation, and the "movement" of the night sky. So congrats! If you take any more, I'd love to see them. Space is so cool. Where's my spacebike? It's passed 2001...

[Night Vision]

are they real? photoshopped? hahahahah

just read Glyn's post, just kidding  ;)

[h2olawyer]

Thanks, all -

No, not Photoshopped - but they are digitally processed.  I have a hard time justifying buying Photoshop - the new version is over $600 and all I would use it for is astrophotos.  Photoshop Essentials does not deal with 16 bit pictures very well and lacks a couple tools that the good astrophotographers use to get the last bit of pop out of their pix.

As for following the sky (compensating for the rotation of the Earth), there are two separate things that make it easier.  First, the tripod & mount are aligned with the celestial pole, along the Earth's axis.  This process takes me about 45 minutes.  The mount for my scope is computerized and has a special routine built in to get a very good (but not perfect) polar alignment.  Basically, I get all set up, run through the basic alignment routine so the mount knows where things are in the sky.  It uses GPS to locate the mount on Earth, then with the scope roughly aligned (polar alignment tube pointing to Polaris), and marks on the mount aligned, the routine starts.  The mount automatically slews to bright stars and I center them in the eyepiece, pressing a button on the controller to tell the software the star is centered.  This process uses 6 total stars.  Then I can use any bright star and run a polar alignment routine that is also part of the scope's software.  I normally run that routine twice - once to the East and again to the West.  Then I run another basic alignment routine.

When I'm finished, I can use the software to find any of about 40,000 different objects in the sky.  Many of the objects are not visible with my telescope (I need more aperture) but can be photographed with what I have.  The software and mount are pretty accurate and the object I seek is nearly dead center in a medium magnification eyepiece about 95% of the time.

To get the mount perfectly polar aligned, I need to perform a 'drift alignment'.  This involves watching how a star moves relative to the cross hairs in an eyepiece.  I haven't done this yet and need the right eyepiece before I can do it right.  However, the software alignment procedure does get me very close.

The second aid is to use a guide camera and a second telescope attached to the imaging scope.  The image from the guide camera is fed through a piece of freeware called Push Here Dummy.  The guide camera is attached to both the laptop and the telescope mount.  It locks on to a star and automatically tracks it, compensating for any movement the star makes relative to the pixels in the camera.  There are lots of adjustments that can be made to how precise the pixel measurement is and how much it corrects where the mount points.  That setup has taken me about 6 nights of just sitting in front of my laptop, watching stars and taking increasingly longer exposures with the Canon DSLR.  Before the latest night out, the longest I could go was a 2 minute exposure before things would go wrong.  Part of the problem was my polar alignment wasn't good enough, part was getting the correct balance of the equipment, and the rest was tweaking all the adjustments in the guiding software.  I can still get things sorted a bit better, but I am limited by having a lower quality mount.  I'm pushing it pretty far with both weight and compensating for the lower quality geartrain.  I should be able to get exposures up to 10 minutes with 60% to 70% of those actually usable for processing.

Before digital cameras, some poor schmuck had to sit at the telescope. with a film camera attached, looking through a guidescope and manually tracking a star for several hours.  Many astrophotos were ruined when the astronomer fell asleep during the process.  It was really an exercise in patience & fortitude.

Learning the process was the main reason I was absent from the forum for several months over the winter.  Although I still have tons to learn, getting to this point is probably the biggest hurdle.  Achieving round stars in 5 minute exposures is what takes the most time, trial & error to learn.  Much of that is just getting out and learning how to compensate for the shortcomings in the mount, then figuring out the proper settings for the guiding software to use.  When using lower end, mass produced mounts, there are major problems with periodic error (inherent in all geartrains) and backlash.

Hope I haven't bored everyone to tears yet!

H₂O

[Glyn]

I still can't believe the perfect clarity of the original moon photo's with chest mounted camera's with manual focusing and no viewfinders. Apparently they got them right first time... Those guys were masters in the art. I think you pics are a more honest representation of space however. 

[h2olawyer]

Perfect clarity of lunar photos is due to no atmospheric distortion.  They practiced using those cameras on Earth for literally hundreds of hours.  NASA released only the best photos - of the many hundreds - even thousands taken.  Also, those photos were normally cropped to get the subject centered in the picture.  Like any decent photographer, they would take several exposures for each subject, with slight adjustments in focus, f/stop and framing.

I was out last night doing some experimentation with my DSLR.  I set it up on a tripod and without looking through the viewfinder or using the LCD screen, pointed it in the general direction of M31 - the Andromeda Galaxy.  Got it dead center with the third shot.  Took several images, changing the focus and exposure settings each time.  Took me about 3 minutes and I got a half dozen great, sharp pix out of the 20 or so I shot.  Nothing I'd want to show off, but just wanted to see if it could be done without checking the aim or fine focus.  It isn't difficult at all.  I would have been faster if I'd had some practice before I tried it.

H₂O

[Rick G]

And I thought I was doing good to spot the International space station, going over ! Well done Rob.

[h2olawyer]

Well, the rest of the story for locating and framing things in a camera without looking through a viewfinder or the LCD screen is to use a fairly wide angle lens.  I had a 50mm lens on my Canon 450D to shoot Andromeda.  (about equal to an 85mm lens on a typical 35mm film camera)  As long as what you want to take a picture of is somewhat close to the center and if you have a lens with a particularly large depth of focus, it isn't all that difficult to take sharp photos.  There are lenses that are focused @ infinity and still get sharp pictures just a few feet away.  I'm sure Hasselblad had such lenses in the 1960s.

Finding the Andromeda Galaxy isn't all that difficult.  Start at the upper left star in the Great Square of Pegasus, count the two brightest stars to the left,  Go about half way between that star & the constellation Cassiopaeia and you should bee in the ballpark of the Andromeda Galaxy.  That was the first deep space object I attempted to find with binoculars last summer and also the first object I sought out the first night I had my telescope.  Under really dark skies, it is visible to the naked eye as a yellow / grey smudge.  I haven't seen it without optical aid yet, as I haven't been out under dark skies when it is higher up in the sky.

As for the pix through the telescope, I take a long time getting the focus just right.  Can't use the autofocus with that setup.  At least with the "Live View" capability of the camera, I can point to a bright star and use the diffraction spikes (common to most Newtonian & Ritchey-Chretien type scopes) to get the focus sharp.  A very small movement of the focuser makes a relatively big change in focus - even with a motorized focuser.  I still need to get the computer focus controller - it makes full use of the stepper motor in the focuser & controls the focuser movement to 0.001 inch!

H₂O

EDIT:  You can find out when the ISS or other cool stuff is visible by going to this site & entering your location:

http://www.heavens-above.com/

[Glyn]

It would be good to see some of the NASA out of focus moon shots and mistakes. Is there a web site where these can be seen I wonder?

[YellowJacket!]

100k points for amature astronomers.  Interesting read!

http://www.foxnews.com/story/0,2933,534160,00.html

David

[Walt_M.]

Talk about 'right place, right time!'

[h2olawyer]

It's amazing all the contributions amateur astronomers are making to the science.  Many of the recent comet discoveries have been made by amateurs systematically scanning the sky.

H₂O