Approve the Cookies
This website uses cookies to improve your user experience. By using this site, you agree to our use of cookies and our Privacy Policy.
OK
Index  •   • New posts  •   • RTAT  •   • 'Best of'  •   • Gallery  •   • Gear  •   • Reviews
Guest
New posts  •   • RTAT  •   • 'Best of'  •   • Gallery  •   • Gear  •   • Reviews
Register to forums    Log in

 
FORUMS Photo Sharing & Visual Enjoyment Astronomy & Celestial 
Thread started 01 Sep 2013 (Sunday) 17:43
Search threadPrev/next
sponsored links
(this ad will go away when you log in as a registered member)

First go with Astrotrac - pleased so far

 
Madweasel
Cream of the Crop
Avatar
6,224 posts
Likes: 60
Joined Jun 2006
Location: Fareham, UK
     
Sep 01, 2013 17:43 |  #1

After several years of persevering with my flimsy home-made mount, I finally picked up a secondhand Astrotrac from eBay and last night was my first opportunity to give it a try. I already have some beefy Manfrotto gear to mount it on (058 Triaut legs and 405 Pro Geared Head), so adjusting polar alignment was not too bad. I think there's room for improvement on that, and I've found out how to get the polar scope focused properly.

I tried a few different targets, first with the 70-200/4L at 200mm, and then, to give it a sterner test, with the 100-400L at 400mm, both on the 7D. I found pointing at the target so much easier with such sturdy gear. All these images were stacked in Deep Sky Stacker and then processed in Photoshop. My processing skills are still quite rudimentary, added to which I think the "flats" I shot are not as flat as they should be, so I might need to revisit that.

First, here is the Andromeda Galaxy at 200mm, made from 14 30s exposures at ISO3200, plus two 60s exposures at ISO1600 (these were just tests of tracking at longer exposure - the 120s exposure I took had slight trailing, so I didn't use it). I lost colour in my DSS processing here. I'll probably come back to it after I've improved my flats. Limiting magnitude in this and most of these shots is about 15.0.

PHOTOBUCKET EMBEDDING IS DISABLED BY THIS MEMBER.
Photobucket sends ads instead of embedding photos from their free galleries.
Click the link (if available) below to see the image in a gallery page.

http://i72.photobucket​.com …lr1small-_zpsbf093508.jpg (external link)


I then turned to the near zenith and shot the North America Nebula region beside bright star Deneb. This was only two 30s exposures at ISO3200, but with the darker zenith sky I've got close to mag 16, and the nebulosity is showing up quite well. DSS counted 6,000 stars in this image.

PHOTOBUCKET EMBEDDING IS DISABLED BY THIS MEMBER.
Photobucket sends ads instead of embedding photos from their free galleries.
Click the link (if available) below to see the image in a gallery page.

http://i72.photobucket​.com …1small--2_zps29e432c9.jpg (external link)


I then put the 100-400 on and returned to Andromeda. This is just five exposures at f/5.6, ISO3200, four of them at 30s, one at 60s.

PHOTOBUCKET EMBEDDING IS DISABLED BY THIS MEMBER.
Photobucket sends ads instead of embedding photos from their free galleries.
Click the link (if available) below to see the image in a gallery page.

http://i72.photobucket​.com …1small--3_zps87761a4b.jpg (external link)


I then moved to the Triangulum Galaxy, which I've only ever captured as a faint blob before. This is just four exposures, f/5.6 ISO3200, three at 30s and one at 60s. I'm so pleased to be able to see traces of the spiral arms.

PHOTOBUCKET EMBEDDING IS DISABLED BY THIS MEMBER.
Photobucket sends ads instead of embedding photos from their free galleries.
Click the link (if available) below to see the image in a gallery page.

http://i72.photobucket​.com …1small--5_zps5e74412e.jpg (external link)


Next the Perseus Double Cluster, just three 30s exposures, other settings as before. Focus had drifted slightly here - the 100-400 seems quite sensitive to temperature changes.

PHOTOBUCKET EMBEDDING IS DISABLED BY THIS MEMBER.
Photobucket sends ads instead of embedding photos from their free galleries.
Click the link (if available) below to see the image in a gallery page.

http://i72.photobucket​.com …1small--4_zpsec05e64c.jpg (external link)


Finally I turned towards the Ring Nebula, M57. I know it's very small, but I thought I'd see how it came out at 400mm. This is seven 30s exposures at f/5.6, six at ISO3200 and one at ISO6400. The limiting magnitude here is about 16.3, the faintest I've yet managed.

PHOTOBUCKET EMBEDDING IS DISABLED BY THIS MEMBER.
Photobucket sends ads instead of embedding photos from their free galleries.
Click the link (if available) below to see the image in a gallery page.

http://i72.photobucket​.com …1small--6_zps6466ab29.jpg (external link)


Also, when scouring the image to remove hot pixels (DSS doesn't seem to do this even though I've got the box ticked) I discovered a faint fuzzy blob in the extreme bottom-right corner. I checked against Wikisky and identified it to be NGC6700, a 13th magnitude galaxy at a rough distance of 200 million light years, my most distant object imaged. To show it, and also the full-res image of M57, I clipped them out at 100% here.

PHOTOBUCKET EMBEDDING IS DISABLED BY THIS MEMBER.
Photobucket sends ads instead of embedding photos from their free galleries.
Click the link (if available) below to see the image in a gallery page.

http://i72.photobucket​.com …mall-6700_zpse476e147.jpg (external link)


I've been really pleased with this first go with the Astrotrac - I was only outside for about an hour, though processing today took considerably longer. I'm sure I can do better, by improving the alignment and improving my flats to allow more severe processing, not to mention improving my processing tricks.

I thought people interested in the Astrotrac would like to see some examples (which is why I haven't cropped these images, except to remove edge artefacts, so you can see the field of view), and I'd also be very happy to hear comments and criticisms on these images. I'm keen to learn from some of the more experienced astro-imagers on here.

Mark.

  
  LOG IN TO REPLY
sponsored links
(this ad will go away when you log in as a registered member)
the ­ jimmy
Goldmember
Avatar
1,423 posts
Likes: 20
Joined Dec 2009
Location: west coast of Florida
     
Sep 01, 2013 18:57 |  #2

Great shots and execution using the Astrotrac, like the M31 shots especially, even though the others are just as well done.




  
  LOG IN TO REPLY
samsen
Cream of the Crop
Avatar
7,468 posts
Likes: 239
Joined Apr 2006
Location: LA
     
Sep 02, 2013 01:42 |  #3

Impressive.


Weak retaliates,
Strong Forgives,
Intelligent Ignores!
Samsen
Picture editing OK

  
  LOG IN TO REPLY
stargazer24
Member
93 posts
Joined Aug 2013
     
Sep 02, 2013 01:59 |  #4

Awesome pics! Just flat out awesome!




  
  LOG IN TO REPLY
coninos
Member
Avatar
83 posts
Likes: 2
Joined Oct 2011
     
Sep 02, 2013 04:08 |  #5

Lovely shots. Been getting intro astrophotography lately myself and came accross deep sky stacker as well but I do not know how to enhance my usage of DSS.

Do you mind sharing a few tips or provide some references so that I could study a bit more?


Website (external link)
flickr (external link)Facebook (external link)
500px (external link)

  
  LOG IN TO REPLY
rfdesigner
Member
147 posts
Joined Aug 2013
Location: UK
     
Sep 02, 2013 06:36 as a reply to  @ coninos's post |  #6

Great start, M31 is certainly showing.

Have you removed the IR filter from the camera or not?.. the North American Nebula being mostly Ha really needs it.

M33 is one of the hardest Messier galaxies to image because the surface brightness is so low. Nice to see you had a go and that it's clearly visible especially with so little data.

Will the astrotrack allow you to track for an hour?. (i.e. 60 x 1minute frames). doing so on M33 would make the photo start to pop.

There's no photo there that's plain wrong, except for needing more data.. something in common with almost all astro images :)

Have a look at techniques that allow you to stretch the image without losing star colour..

Derek


30D, 18~55mm, 100mmf2.0, various Praktica, Atik 383L+ mono & filter wheel, 12" imaging telescope

  
  LOG IN TO REPLY
Madweasel
THREAD ­ STARTER
Cream of the Crop
Avatar
6,224 posts
Likes: 60
Joined Jun 2006
Location: Fareham, UK
     
Sep 06, 2013 17:22 as a reply to  @ rfdesigner's post |  #7

Thanks all for positive feedback.

Derek, no the body is unmodded, so I guess I'm at a disadvantage for all the Ha stuff out there. I'll have to see if I want to go that far. I'm now trying to build up more data. At the same time I'm improving the polar scope, which is quite flimsy and seems to have suffered a bit in its former life.

The Astrotrac will track for a total of just under two hours, before you have to rewind the thread.


Mark.

  
  LOG IN TO REPLY
rfdesigner
Member
147 posts
Joined Aug 2013
Location: UK
     
Sep 07, 2013 04:57 |  #8

If the polar scope is damaged then research 'drift alignment'. MUCH more accurate and doesn't need you to be able to see polaris. You can still use the polar scope to rough align first then do a quick and dirty drift align, you'll then be sufficiently aligned.

Only let the lack of Ha put you off dim Ha targets, you'll be about 25% as sensitive as a modified camera. M42 will still be in range.

Derek


30D, 18~55mm, 100mmf2.0, various Praktica, Atik 383L+ mono & filter wheel, 12" imaging telescope

  
  LOG IN TO REPLY
Madweasel
THREAD ­ STARTER
Cream of the Crop
Avatar
6,224 posts
Likes: 60
Joined Jun 2006
Location: Fareham, UK
     
Sep 07, 2013 17:06 as a reply to  @ rfdesigner's post |  #9

Here's another go at the first stack in my original post, with better processing.

PHOTOBUCKET EMBEDDING IS DISABLED BY THIS MEMBER.
Photobucket sends ads instead of embedding photos from their free galleries.
Click the link (if available) below to see the image in a gallery page.

http://i72.photobucket​.com …/M31small_zps75​d61292.jpg (external link)

Mark.

  
  LOG IN TO REPLY
Naturalist
Adrift on a lonely vast sea
Avatar
5,484 posts
Gallery: 93 photos
Likes: 899
Joined May 2007
Location: Tallgrass prairies of northwest Minnesota
     
Sep 07, 2013 17:07 |  #10

What do you guys do to get rid of the digital noise I get in my images? I shoot wide open, 30 sec at ISO 800.


Doug
My Gear List
http://www.douglasbrow​nsr.com (external link)
Entered: 2-16-84 Passed: 5-22-84 Raised: 6-19-84

  
  LOG IN TO REPLY
Madweasel
THREAD ­ STARTER
Cream of the Crop
Avatar
6,224 posts
Likes: 60
Joined Jun 2006
Location: Fareham, UK
     
Sep 07, 2013 17:15 |  #11

Naturalist wrote in post #16276930 (external link)
What do you guys do to get rid of the digital noise I get in my images? I shoot wide open, 30 sec at ISO 800.

It's the stacking process that gets rid of a lot of it. Noise goes down with the square root of the number of lights used. Taking darks at the same time can also remove a lot. The rest is in processing, taking the sky down in brightness and colour.


Mark.

  
  LOG IN TO REPLY
rfdesigner
Member
147 posts
Joined Aug 2013
Location: UK
     
Sep 08, 2013 06:27 |  #12

You can apply selective blurring to reduce the grain.. you can also apply selective blur to the colour only, you can reduce the noise by about 75% doing that.. some people get way with more.

Fundamentally though you need time. I tend to shoot 300s mono frames + 100s colour frames, I'll stack about 5 hours of data. The longest shot I know of used 2 solid weeks of data.. and yes that was the Hubble.

Derek


30D, 18~55mm, 100mmf2.0, various Praktica, Atik 383L+ mono & filter wheel, 12" imaging telescope

  
  LOG IN TO REPLY
alliben
Senior Member
Avatar
304 posts
Gallery: 36 photos
Likes: 158
Joined Apr 2011
     
Sep 10, 2013 08:56 |  #13

I'm also new to DSS and have lost color in my Andromeda attempts. Any advice for retaining color?




  
  LOG IN TO REPLY
alliben
Senior Member
Avatar
304 posts
Gallery: 36 photos
Likes: 158
Joined Apr 2011
     
Sep 10, 2013 08:58 |  #14

I have another question. I'm using a T2i with my 100-400L on a barn door tracker. How did you focus with that lens? I couldn't pick up any stars in live view.




  
  LOG IN TO REPLY
Madweasel
THREAD ­ STARTER
Cream of the Crop
Avatar
6,224 posts
Likes: 60
Joined Jun 2006
Location: Fareham, UK
     
Sep 10, 2013 17:29 |  #15

alliben wrote in post #16284505 (external link)
I'm also new to DSS and have lost color in my Andromeda attempts. Any advice for retaining color?

It seems best to give the saturation a push within DSS. I've found between 15% and 20% works best. I sometimes use Photoshop to reduce saturation of the dark parts and boost it in the highlights (the stars) - it works better with some shots than others.


Mark.

  
  LOG IN TO REPLY
sponsored links
(this ad will go away when you log in as a registered member)

3,652 views & 0 likes for this thread
First go with Astrotrac - pleased so far
FORUMS Photo Sharing & Visual Enjoyment Astronomy & Celestial 
AAA
x 1600
y 1600

Jump to forum...   •  Rules   •  Index   •  New posts   •  RTAT   •  'Best of'   •  Gallery   •  Gear   •  Reviews   •  Member list   •  Polls   •  Image rules   •  Search   •  Password reset

Not a member yet?
Register to forums
Registered members may log in to forums and access all the features: full search, image upload, follow forums, own gear list and ratings, likes, more forums, private messaging, thread follow, notifications, own gallery, all settings, view hosted photos, own reviews, see more and do more... and all is free. Don't be a stranger - register now and start posting!


COOKIES DISCLAIMER: This website uses cookies to improve your user experience. By using this site, you agree to our use of cookies and to our privacy policy.
Privacy policy and cookie usage info.


POWERED BY AMASS forum software 2.1forum software
version 2.1 /
code and design
by Pekka Saarinen ©
for photography-on-the.net

Latest registered member is Phree_ed
789 guests, 248 members online
Simultaneous users record so far is 15144, that happened on Nov 22, 2018

Photography-on-the.net Digital Photography Forums is the website for photographers and all who love great photos, camera and post processing techniques, gear talk, discussion and sharing. Professionals, hobbyists, newbies and those who don't even own a camera -- all are welcome regardless of skill, favourite brand, gear, gender or age. Registering and usage is free.