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Astrophotography and Sketching >> Beginning and Intermediate Imaging

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magic612
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Reged: 09/30/08

Loc: S. of Chicago's light dome
Here we go: New to me, Canon T3 (1100D)
      #5627961 - 01/17/13 12:03 PM

Okay, I guess it's new period, not just new to me. I had some money saved from Christmas, and had been considering what to get in terms of astro-equipment. Along comes an Amazon.com offer for a decent price on a new Canon EOS T3 set up. Talk to the wife, who's been interested in hopping back into general photography herself, and we took the plunge.

I know about the need for solid mounts. I know about barn door trackers and wide-field astrphotography (I've done some of that in the past). I know thru-the-scope astrophotography has a steep learning curve, and I'm reasonably sure that accurate polar alignment is still essential. I have a SkyViewPro mount, that tracks well, on a very solid pier/tripod mount I built, and a 6" f/5 reflector with a 2" focuser that throws up a good image. I also have a laptop.

Other than a Bahtinov mask for focusing and a 2" adapter with T-ring, what other equipment do I need to get started with the very, very basics of the thru-the-scope stuff nowadays?


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shawnhar
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Reged: 06/25/10

Loc: Knoxville, TN
Re: Here we go: New to me, Canon T3 (1100D) new [Re: magic612]
      #5627980 - 01/17/13 12:18 PM

Coma corrector would be nice, you will probably see lots of it in your pics at F5.
Drift alignment will be important.
You can use the EOS Utility to live-view adn get focused and framed on target, then use the little clock icon to auto-take "x" exposures at "x" length, that's pretty handy.
Deep sky stacker is free and will calibrate all your files.
You need the lights, darks and flats, throw those in DSS and your'e cookin!
I would start with a bright target like Orion and try 30 second subs, if you see trailing, go back to drift alignment and see if you can get better polar alignment.
Good luck! Look forward to some pics!


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magic612
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Reged: 09/30/08

Loc: S. of Chicago's light dome
Re: Here we go: New to me, Canon T3 (1100D) new [Re: shawnhar]
      #5629649 - 01/18/13 10:36 AM

Shawn, thank you for the helpful response.

I'm not worried about coma (yet). I know it will be there, but I figure I should get better at taking / stacking / manipulating images before spending money on that particular accessory immediately.

Drift alignment... yeah. Guess I'll have to learn that. (AHHH!)

Good to know about the EOS Utility - I assume that's just using the USB port to send the image to my laptop for live-view?

Deep sky stacker: Cool, will do.

Uhhh... "lights, darks and flats" - I guess I can learn about that at astropix.com or somewhere like that? I'm completely clueless as to what that means at the moment (please pardon my ignorance!).

I took some unguided, 4 to 15 second exposure last night at 3200 ISO just using the included 18-55mm lens, and was amazed at what it picked up (when I finally managed to focus it well). It picked up the Double Cluster, M35, M36, M37, M38 an obviously M42 with no problem.

I'm really looking forward to doing this - I just know I'll have to go slow!


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guyroch
Vendor (BackyardEOS)
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Reged: 01/22/08

Loc: Under the clouds!
Re: Here we go: New to me, Canon T3 (1100D) new [Re: magic612]
      #5629662 - 01/18/13 10:44 AM

Quote:

Good to know about the EOS Utility - I assume that's just using the USB port to send the image to my laptop for live-view?




Yes, the T3/1100D requires only the camera supplied usb cable for software control. Speaking of software I may know a guy that knows a guy that knows about software

Guylain


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shawnhar
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Reged: 06/25/10

Loc: Knoxville, TN
Re: Here we go: New to me, Canon T3 (1100D) new [Re: guyroch]
      #5629886 - 01/18/13 12:41 PM

Yup, USB cable to laptop is all you need to run EOS Util or BackyardEOS. Use live view to find a star, zoom in 200x and get the star as small as possible to focus. Bahtinov mask is really handy, or Backyard EOS has a focus assist funtion.
Drift alignment simulator
http://www.petesastrophotography.com/
Pete did a really good job of explaining the why and how.

There is also an article here on CN on how to use your DSLR to drift align:
http://www.cloudynights.com/item.php?item_id=2838

Lights are your regular exposures of the target.
Darks are easy, just cap the scope and take 20 or so exposures without changing anything else, they need to be the same ISO, duration and temp as the lights. You can even remove the camera cap, it and take them while you are breaking down gear. (Do the flats 1st!)
Flats are very short exposures at the same ISO, aimed at an evenly illuminated bright surface. Turn camera to AV and click click, 20 or so works great. They deal with dust and vignetting, darkening in the corners of the image due to the camera chip not being evenly illuminated. These can be kinda tricky, adjust the exposure setting so the histo is half or a little more should be a good start. Make sure not to change anything from when you take the lights to taking flats, don't move the camera, leave it on the scope just like it was when taking the lights.
You don't need flats or darks to start, but darks get rid of hot pixels in the camera and flats help with the darkening of the corners.
After you stack in DSS make sure the "Do not apply changes" is clicked in the "Save picture" dialog.
Then take that tiff and open it with Photoshop, Fitswork, StarTools(you can try for free and do everything but save the final image), or whatever software you have. Fitswork is free and works well to learn how to "stretch" the histogram. You have to use curves, can't just brighten the entire image.


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magic612
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Reged: 09/30/08

Loc: S. of Chicago's light dome
Re: Here we go: New to me, Canon T3 (1100D) new [Re: shawnhar]
      #5630031 - 01/18/13 02:32 PM

Awesome, thanks guys. Like I said, steep learning curve!

I have Photoshop Elements, so I'll probably stick with that given my familiarity with it. The rest doesn't sound difficult - it'll just take me reading it and doing it a few times to get used to doing those things, I think.

Thanks again!


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bouffetout
scholastic sledgehammer


Reged: 11/21/12

Loc: Canada
Re: Here we go: New to me, Canon T3 (1100D) new [Re: magic612]
      #5657831 - 02/02/13 10:06 AM

The best advice given to me when I started astroimaging was
Make a" to do" list and follow it everytime you setup...
Trust me it will save you lots of time wasted because you forgot one little detail...
And for processing ,GIMP2 is free and very complete but only takes 8bits for the moment...but they are working on the next edition that will take 16bits ,and there are more and more plug-ins for astrophotography !
Clear sky and have fun !
Maxx


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magic612
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Reged: 09/30/08

Loc: S. of Chicago's light dome
Re: Here we go: New to me, Canon T3 (1100D) new [Re: bouffetout]
      #5700391 - 02/25/13 06:44 PM

Maxx, thanks for the tip. I've been crazy-busy the last few weeks, and today I finally got some time to relax a bit.

I do have a general question for everyone though. I have some older Pentax K-mount lenses back from when I tried my hand at astrophotography some 20 years ago or so. The lenses are still in good shape, have nice fast apertures (generally), etc. In any case, I know that adapters exist for Pentax K lenses to Canon EF bodies. But I have read in a place or two that the aperture 'bar' that sticks out the back of the K-mount lenses can foul the mirror as it flips up on Canon bodies.

Given the Canon body I have, can I used an adapter on my K-mount lenses and be okay? Is there a way for me to test this without possibly ruining my miror?

Thanks!


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Phil Sherman
Pooh-Bah


Reged: 12/07/10

Loc: Cleveland, Ohio
Re: Here we go: New to me, Canon T3 (1100D) new [Re: magic612]
      #5701307 - 02/26/13 10:05 AM

You'll need to get out some measuring tools and see what the clearances are with the K to Canon adapter. I believe the Canon has a special function to lift the mirror for manual cleaning which will let you measure the clearance between the front flange and the mirror.

If you no longer use the old (film?) camera, there's always the possibility of grinding off the aperture bar.

You might want to get an electronic copy of Ron Wodowski's "The New CCD Astronomy". It's not specifically targeted at DSLR imaging but there's lots of excellent background information about imaging that applies to DSLRs as well as CCD astro cameras.

Guylan's Backyard EOS is a great camera control program. Mike Unsold's ImagesPlus is a wonderful image processing program that's targeted for DSLR users and will process FITS images from any astro camera. IP is lots less expensive than Photoshop and doesn't require purchasing additional plugins for AP image processing.

When you use your Canon for astrophotography (AP), you must use RAW or RAW+JPEG recording mode. In-camera JPEG processing can easily discard over 50% of the photons gathered in an AP image. The camera's "long exposure noise reduction" feature is not as effective as using "darks" because it uses a single dark frame for each exposure, which is less effective than a "master dark" that's an average of 10-20 dark frames.

The battery in the camera isn't designed to take an hour or so of 1-5 minute exposures. An AC adapter is the solution for this problem. Try getting one on eBay, it's much less expensive than the Canon branded one. I built my own 8V external supply that runs off of the 12V system I use for my astro gear. I cut the AC adapter off of the one I bought on eBay and use only the cord and battery adapter.

The article mentioned for drift alignment is very good but I'd add a few things to it:

1. You don't have to find a "brighter" star. Just point the scope in the appropriate place and image. There'll be plenty of stars visible in the image.

2. My exposure times are 2*n + 10 seconds where n is the slew time. The first 5 seconds are tracked and the second slew is 5 seconds longer than the first. This makes the end of the trail pass through the tracked star which makes it a lot easier to judge the alignment. I also slew E first. Slewing E at sidereal rate stops tracking then the W slew has no gear slack to recover from. I use a 70 second image time with two 30 second slews. My mount adjustment resolution matches nicely with this length exposure. If I was pier mounted, I'd definitely try for a more accurate polar alignment using longer slews.

Phil


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guyroch
Vendor (BackyardEOS)
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Reged: 01/22/08

Loc: Under the clouds!
Re: Here we go: New to me, Canon T3 (1100D) new [Re: Phil Sherman]
      #5701417 - 02/26/13 11:07 AM

Quote:

Guylan's Backyard EOS is a great camera control program.






Guylain


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rflinn68Moderator
Carpal Tunnel


Reged: 03/09/12

Loc: Arkansas
Re: Here we go: New to me, Canon T3 (1100D) new [Re: guyroch]
      #5701456 - 02/26/13 11:30 AM

Quote:

Quote:

Guylan's Backyard EOS is a great camera control program.








Guylain




Definitely a must have! I love my BackYardEOS and would be lost without it. Some of the best money we've spent!


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