Username:

Password:

Altair AstroDIO DehumidifiersAtik CamerasModern AstronomyDavid HindsNe3 Filters

Author Topic: Cygnus and Cassiopeia widefield  (Read 2779 times)

0 Members and 1 Guest are viewing this topic.

Offline Dave Smith

  • Poster God
  • *****
  • Posts: 1158
    • http://astrosnaps.co.uk
Cygnus and Cassiopeia widefield
« on: 19:33:14, 18 September, 2012 »
These were both taken with a 24-105 mm zoom lens set at 24mm and f4. Both were an hour of 5 minute subs at iso 800.

Cygnus



Cassiopeia



I am quite disappointed with these images. Firstly I didn't get good focus and secondly the focus seems to vary quite a lot across the image. I'm really not sure what I can do about that. The lens is an L lens and is supposedly of top quality.

Dave
Website: http://astrosnaps.co.uk

Megrez 90, NEQ6, Atik 460EX M with Astrodon filters, DMK21 in finder guider, SkyShed POD. Celestron 9.25 for visual.
Software: SGPro with PHD2, Nebulosity4, MaximDL  and PS CS2.
Solar imaging:SkyWatcher ST120 with Daystar Quark Chromosphere, Rowan tilt adapter and ZWO ASI 174MM camera. Software: FireCapture, AS!2, Imppg and PS CS2.

Offline tomhow

  • Tom How
  • Galactic Poster
  • ******
  • Posts: 3112
  • Making equipment is far more fun than buying it.
    • The Curdridge Observatory
Re: Cygnus and Cassiopeia widefield
« Reply #1 on: 19:41:25, 18 September, 2012 »
How (and which) was the camera attached to the lens?
Tak Sky 90, Atik 490, Homemade Mount, OAG, Lodestar

The Curdridge Observatory

Offline Dave Smith

  • Poster God
  • *****
  • Posts: 1158
    • http://astrosnaps.co.uk
Re: Cygnus and Cassiopeia widefield
« Reply #2 on: 19:51:41, 18 September, 2012 »
The camera used was a Canon 40D (modded) with the lens attached by the normal bayonet. I am guessing that you are thinking that the lens may not be properly aligned. I have used this lens for normal photography for a number of years and it has produced excellent photos. The camera was driven on an astrotrac.

Dave
Website: http://astrosnaps.co.uk

Megrez 90, NEQ6, Atik 460EX M with Astrodon filters, DMK21 in finder guider, SkyShed POD. Celestron 9.25 for visual.
Software: SGPro with PHD2, Nebulosity4, MaximDL  and PS CS2.
Solar imaging:SkyWatcher ST120 with Daystar Quark Chromosphere, Rowan tilt adapter and ZWO ASI 174MM camera. Software: FireCapture, AS!2, Imppg and PS CS2.

Offline swashy

  • UKAI GFX Guru
  • Administrator
  • Galactic Poster
  • *****
  • Posts: 14593
    • Swash Astro
Re: Cygnus and Cassiopeia widefield
« Reply #3 on: 19:57:16, 18 September, 2012 »
Lots of data Dave, but I can understand your dissapointment. It's possibly caused by barrel distortion, which has then been amplified by the tracking during the exposure. Canon has software for correction of their lenses so may be worth doing a google for Canon DPP (or you may already have it) and see if you can correct it somewhat on the raws first

Ade

Imagine...  above us only sky!


Offline tomhow

  • Tom How
  • Galactic Poster
  • ******
  • Posts: 3112
  • Making equipment is far more fun than buying it.
    • The Curdridge Observatory
Re: Cygnus and Cassiopeia widefield
« Reply #4 on: 19:59:13, 18 September, 2012 »
Your right, it doesn't feel like an unflat camera. Ade sounds like he knows what he's talking about :)
Tak Sky 90, Atik 490, Homemade Mount, OAG, Lodestar

The Curdridge Observatory

Offline Dave Smith

  • Poster God
  • *****
  • Posts: 1158
    • http://astrosnaps.co.uk
Re: Cygnus and Cassiopeia widefield
« Reply #5 on: 20:04:22, 18 September, 2012 »
Thanks Ade and Tom, I'm off to search Google now.

Dave
Website: http://astrosnaps.co.uk

Megrez 90, NEQ6, Atik 460EX M with Astrodon filters, DMK21 in finder guider, SkyShed POD. Celestron 9.25 for visual.
Software: SGPro with PHD2, Nebulosity4, MaximDL  and PS CS2.
Solar imaging:SkyWatcher ST120 with Daystar Quark Chromosphere, Rowan tilt adapter and ZWO ASI 174MM camera. Software: FireCapture, AS!2, Imppg and PS CS2.

Offline Dave Smith

  • Poster God
  • *****
  • Posts: 1158
    • http://astrosnaps.co.uk
Re: Cygnus and Cassiopeia widefield
« Reply #6 on: 20:39:56, 18 September, 2012 »
I've had a play with DPP and have found how to correct image distortion. Unfortunately it doesn't do anything for the poor focus. It does seem a very useful tool so thanks for introducing me to it. I will have another try with this lens from home prior to going on another astro camp next month. Unfortunately I was relying on using the APT focusing routine but couldn't with this lens as no star was visible in live view and I forgot to take my Batinov mask with me.

Dave
Website: http://astrosnaps.co.uk

Megrez 90, NEQ6, Atik 460EX M with Astrodon filters, DMK21 in finder guider, SkyShed POD. Celestron 9.25 for visual.
Software: SGPro with PHD2, Nebulosity4, MaximDL  and PS CS2.
Solar imaging:SkyWatcher ST120 with Daystar Quark Chromosphere, Rowan tilt adapter and ZWO ASI 174MM camera. Software: FireCapture, AS!2, Imppg and PS CS2.

Offline psjshep

  • Phil, who still has a job
  • Administrator
  • Galactic Poster
  • *****
  • Posts: 10039
  • Dark nights are back again....
    • Some astro Pics
Re: Cygnus and Cassiopeia widefield
« Reply #7 on: 22:54:11, 18 September, 2012 »
Ade sounds like he knows what he's talking about :)

How much is he paying you!  :butt:
--------------------------------------------------------------------------
Web Images

Offline psjshep

  • Phil, who still has a job
  • Administrator
  • Galactic Poster
  • *****
  • Posts: 10039
  • Dark nights are back again....
    • Some astro Pics
Re: Cygnus and Cassiopeia widefield
« Reply #8 on: 22:55:43, 18 September, 2012 »
I still love these wide field shots, Dave...

What is the galaxy in the Cassiopeia shot?

Phil
--------------------------------------------------------------------------
Web Images

Offline Dave Smith

  • Poster God
  • *****
  • Posts: 1158
    • http://astrosnaps.co.uk
Re: Cygnus and Cassiopeia widefield
« Reply #9 on: 07:58:53, 19 September, 2012 »
Andromeda.

Dave
Website: http://astrosnaps.co.uk

Megrez 90, NEQ6, Atik 460EX M with Astrodon filters, DMK21 in finder guider, SkyShed POD. Celestron 9.25 for visual.
Software: SGPro with PHD2, Nebulosity4, MaximDL  and PS CS2.
Solar imaging:SkyWatcher ST120 with Daystar Quark Chromosphere, Rowan tilt adapter and ZWO ASI 174MM camera. Software: FireCapture, AS!2, Imppg and PS CS2.

Offline John Moore

  • Senior Member
  • ****
  • Posts: 667
    • John Moore - Astronomy Pages
Re: Cygnus and Cassiopeia widefield
« Reply #10 on: 10:49:40, 19 September, 2012 »
I don't know about the Canon lens, but in general most camera lenses aren't that good at wide aperture (most users wouldn't notice the difference anyway). I found with some (admittedly old) Pentax lenses that I needed to stop them down to f5.6 for all three that I tried, to minimise distortions. Unfortunately of course that also increases your exposure times. It might be worth doing some tests at different apertures and examining the corners of each image.

Regards
John Moore

Offline Dave Smith

  • Poster God
  • *****
  • Posts: 1158
    • http://astrosnaps.co.uk
Re: Cygnus and Cassiopeia widefield
« Reply #11 on: 11:17:09, 19 September, 2012 »
Thanks John, I will try that. I have avoided reducing the aperture because of the diffraction spikes the diaphragm introduces. I will have to make a circular aperture of the correct size - just too lazy to have done it before.

Dave
Website: http://astrosnaps.co.uk

Megrez 90, NEQ6, Atik 460EX M with Astrodon filters, DMK21 in finder guider, SkyShed POD. Celestron 9.25 for visual.
Software: SGPro with PHD2, Nebulosity4, MaximDL  and PS CS2.
Solar imaging:SkyWatcher ST120 with Daystar Quark Chromosphere, Rowan tilt adapter and ZWO ASI 174MM camera. Software: FireCapture, AS!2, Imppg and PS CS2.

Offline John Moore

  • Senior Member
  • ****
  • Posts: 667
    • John Moore - Astronomy Pages
Re: Cygnus and Cassiopeia widefield
« Reply #12 on: 17:02:22, 20 September, 2012 »
yes, that's a good point. Another disadvantage of stopping down!

John

 

ukbuysellRemote Imaging from AustraliaSharpSkyblank APTUKAI on Facebook
Powered by SMF 2.0.13 | SMF © 2006, Simple Machines LLC
DarkBreak by DzinerStudio. Theme modified by The UKAI Team

Page created in 0.267 seconds with 37 queries.
TinyPortal © 2005-2012