Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

sgl_2019_sp_banner.thumb.jpg.a0ff260c05b90dead5c594e9b4ee9fd0.jpg

Mark_C

Had a go at imaging the M101

Recommended Posts

Hi all,

This is my first serious attempt at astrophotography and thought I'd share what I have been able to achieve. I was having some initial issues with star trailing/field rotation which I think boiled down to less than optimal polar alignment and flexure of the finderscope.

I've managed to get familiar with the DARV polar alignment method and eimlinated most, if not all of the finderscope flexure. Doing this has helped a great deal in getting longer subs.

I'm fairly pleased with this image, however I think it's a little bit on the noisy side. I think some of that may be due to subtracting only a few dark frames and not taking any flat/bias frames (still not sure on either of these).

This is a combination of around 14 x 5 min subs stacked in DSS, with a bit of tweaking in Photoshop.

post-36814-0-03797100-1403722045_thumb.j

  • Like 19

Share this post


Link to post
Share on other sites

I'm not an imager but would be really chuffed if I had taken that image.

Share this post


Link to post
Share on other sites

If this is your first serious attempt at AP then you've done exceptionally well.  This is a very faint object and deceivingly tricky.  Flats would improve it, but Rome wasn't built in a day.

Carole 

  • Like 2

Share this post


Link to post
Share on other sites

Thanks for the positive comments. :)

I had done a considerable amount of research prior to attempting to image to avoid making too many mistakes and giving up, doing so has really helped things along.

The crucial step to all of this was managing to set up plate solving with Astrotortilla to centre the M101 in the FOV... without this I think I would have struggled..as you've mentioned Carole it's a very faint object and almost undetectable unless exposed for some time. I didn't think it was there at first until I exposed a 2 minute sub and I could see it right bang in the centre of the image, my immediate reaction was WOW, that looks amazing! I decided to carry on taking subs of it while the going was good and I am pleased with the results. Unfortunately it gets light so early this time of year so there is only a few hours of usable imaging time, bit of a pain really. :(

I have to say though that Astrotortilla is an amazing piece of software, it has taken a bit of messing to get working but once all of the obstacles overcome its an absolute godsend and is an essential tool for imagers. It essentially removes the need to carry out star alignments and removes any element of second guessing whether the DSO is in the centre of the frame or not.

I have probably dived in the deep end with regards to choice of DSO but it seems to have paid off, I just need to learn how to take flats/bias and I am sure that will help greatly.

Hopefully if the skies clear again I will get more subs to reduce noise further... I may look in to imaging M81/2 or the M106 as my next target. Just need to get my 60D astro modified or buy a cheap modded 1100 as I am sure there is a lot more Ha detail to be picked up and is currently lacking in the above image.

I guess eventually I will end up buying a CCD but for the moment the DSLR seems to be working fine for me. :)

Mark.

Share this post


Link to post
Share on other sites

That's a superb first image! You've got some star colour there too. Give yourself a pat on the back.

Alexxx

Share this post


Link to post
Share on other sites

That is an excellent first attempt with a tricky target. Nicely done.

A.G

Share this post


Link to post
Share on other sites

I have to agree with everyone... I'd be stoked to take get an image like that at the 1st try!

Share this post


Link to post
Share on other sites

Brilliant, well done! A superb start down (or is it up!) the slippery and expensive slope of AP. That thrill of seeing the first sub pop up on the computer screen and the target object showing where you wanted it and the first hints of detail coming through really is fantastic and stupidly addictive. As for Astrotortilla and plate solving generally, as you say, a total essential to making the very difficult just difficult.

There are several ways to reduce noise; more subs, longer subs, more darks and dithering - that doesn't include cooling, darker skies etc etc etc! Worth trying all four of those.

Bias frames are really easy to do - just take darks, but at the fastest shutter speed your camera can shoot at. Then stack them up and make a master bias file for use in all projects.

Flats are not so easy, but essentially you need a uniform light source (a light panel, a blank computer screen or a t-shirt over the scope pointing at the sky) and expose with the camera in AV mode so that the histogram is about half way along from the left. The optical chain must be identical to when the lights were taken, so just don't move the camera or anything, best to take these at the end of the imaging session. Take lots of frames, stack them up and create the master flat for that set of subs.

Good luck and enjoy!

Share this post


Link to post
Share on other sites

Wow, thanks for all of the positive comments everyone, I really appreciate it! :) And thanks for those tips Gav, I shall try and obtain some more darks/flats/bias frames over the weekend and improve on what I already have. Unfortunately it's not looking like it will be clear here until Sunday night at the earliest. :(

Share this post


Link to post
Share on other sites

That's a great first image. Loads of detail coming through to say it's only 14x5mins. Well done.

Share this post


Link to post
Share on other sites

awesome image and well done. thanks for posting i always love looking at people attempts.

Share this post


Link to post
Share on other sites

Thanks. :) I've just realised there were some other subs I took of the M101 that I didn't realise about so I have stacked these with the ones used to create the image above, doing so appears to have brought out slightly more detail towards near the centre of the galaxy, although I don't really know if it improves on the above image at all really.

I really am gobsmacked at how well these images have turned out considering I have had next to no experience with imaging beforehand, beginners luck perhaps?  :grin:

post-36814-0-20194000-1403995980_thumb.j

  • Like 2

Share this post


Link to post
Share on other sites

Yes, it has brought out a bit more detail. Do take care with processing not to bring out too much noise, though! You're getting there. Well done!

Share this post


Link to post
Share on other sites

Looks good to me and the kit as had a decent work out ,be proud of the image and keep going

Pat

Share this post


Link to post
Share on other sites

Everybody above have already said it.

Beginners luck or not, who cares that's a great image.

I struggled for ages to get this target.

Now that you have this one down, what's next?

Share this post


Link to post
Share on other sites

Long may your "beginners luck" continue!

That 2nd image is even more impressive than the 1st... and I LOVE the 1st!

Please keep posting images like that. It gives total noobs like me something to strive towards when I finally get round to having a crack at it myself.

Share this post


Link to post
Share on other sites

Thanks everybody! I really appreciate the compliments. I hope this encourages anyone, especially those with minimal experience to get out and give imaging a try. I was a bit doubtful at first as to whether everything would work as expected but fortunately it did. I think what is most crucial is getting precise polar alignment. Even with autoguiding, if PA is slightly out it will restrict how long your subs can be. I tried a 10 min sub the other night and there was star trailing so there is definitely room for improvement, although I think play in my mount is causing issues there.

Unfortunately I won't be imaging for a while as my AZ-EQ6 isn't well and is in loads of bits at the moment after me being silly stripping one of the RA worm set screw threads, meaning there's now loads of play in my RA axis as the gears are no longer meshed properly. Whilst stripping the mount I also knocked off a white 3 pin connector from the RA indexer PCB which now has to be soldered back. Things aren't going so well for my mount at the moment, I really hope it all works ok after I (hopefully) reassemble it and hopefully eliminate the play that was present.

If my mount returns back to its duties, I think my next target will be the M63! I love it's patterned structure and is quite dim so will be quite a challenge, I'll perhaps give the M51 a try too.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.