First proper Astrophotos: Orion nebula and Andromeda galaxy

Hey Everyone,

First of all I'd like to wish you all a very happy Christmas and a great new year. Its been a while since I posted last as I have been kept very busy studying my masters in astronomy in Groningen, The Netherlands. I thought I would post these images i took Christmas eve night. I am still quite new to astrophotgraphy and my equipment is still at beginner level. I would love to hear your advice and suggestions on how to improve my imaging. BTW I have a slight problem with wind rocking the OTA very lightly, so I have to make some improvements with that, or wait for a wind free night.

Enjoy.

Equipment:
Meade LXD 75 6"
Nikon D80
Orion 80mm guidescope and Orion starshoot autoguider used in conjunction with PHD.

Image detail:

Orion nebula:
7x5 min exposures at ISO 1600
No filters. Darks, flats and bias frames included

Andromeda Galaxy:
2x5 min exposures at ISO 1600 (Originally 17x5 min taken but they were too "shakey")
No filters. Darks, flats and bias frames included

www.flickr.com/photos/123973306@N06/15934260800/

https://www.flickr.com/photos/123973306@N06/15934260800/

www.flickr.com/photos/123973306@N06/15934275410/

https://www.flickr.com/photos/123973306@N06/15934275410/

Both images are stacked in DSS and processed in PS6

Hi John

You have made quite a good start, much better than my first set of images with a DSLR, the LXD75 will rock in the wind, as it acts like a sail in the slightest of breezes

As far as advice goes, I have plenty of advice, firstly, reduce your ISO speed, ISO 1600 is far too noisy in my opinion, I did some testing when I used to use a DSLR for astro photography and found that increasing the ISO to 1600 resulted in me having to do almost double the amount of frames to counteract the random noise.

Feel free to drop me a PM I'd be glad to help you on your journey

Simon

Hi Simon,

Thanks for the advice. I will knock the ISO down to 800 next time. Also the LXD75/ sail is very true, I found myself trying to use my body as a shield against the wind, didn't work.

I had a lot of trouble with the tracking of the scope (as some of the guys here probably know) and this was a good test to see how it worked now that I have a decent guidescope setup.

Thanks again, I may take you up on that offer.

clear skies,
John

I hope Simon can help you out - I personally would have no idea about using a DSLR. On the guiding, start with shorter shots and only increase to 5 mins and beyond when you are sure the whole setup is working as it should and that the guide scope is rigid with the imaging scope. Again I am ignorant of your set-up.....is polar alignment easy to do with that mount? - that is a must to get pretty close if the guiding is to work on longer shots. One of the very early pointers I got was to improve my focusing....something all imagers need to be careful of. For pinpoint stars that is another must.....I got it all wrong at first
Just some thoughts.....lots to bear in mind when starting out....but well worth all the effort.

Tracking is only as good as your polar alignment, When I used to do a field setup before I went to a Permanent Pier, I used to spend at least 30 minutes getting my polar alignment done, I used the drift alignment technique, I know how challenging that can be in Ireland, especially where I used to live in Cork that 30 min is a long timne for the clouds to roll in and it's 30 min of wasted exposure time.

My advice here would be

1. Get the mount aligned roughly with Polaris
2. Do a drift align
3. Once the mount is aligned, mark on the floor where the tripod legs go and mark on the legs how high each leg is to be level in those three spots, so each time you get the tripod out, you are putting it in more or less the same spot every time

With step 3, this saves time with trying to adjust altitude during your drift align each time.

I can't stress enough about dark frames and flat frames, they make a significant improvement of the overall stacked image. Since you are not cooling your DSLR camera, do what I used to do and take various dark frames at various exposure times within a 5 degree range for example

300S Darks @ 0-4 Degrees C @ ISO 800
300S Darks @ 5-9 Degrees C @ ISO 800
300S Darks @ 10-14 Degrees C @ ISO 800
300S Darks @ 15-19 Degrees C @ ISO 800

For each category, take at least 19 darks and combine that category to make a masterdark 19x300S Dark @ 0-4.........

Then when you take your images, try and categorise your light frames and match them up with the appropriate master dark

Flats are important too, they counteract the effect of vignetting and also imperfections and dust in the optical train, whenever you make any adjustment to the optical train, you are going to re-do flats

Just remember about the ISO, the higher the ISO, the more noisier it becomes, I have seen fantastic images taken with ISO 1600 and above, but past experience with me doing ISO 1600 ended up taking double the amount of exposures to counteract the noise, ISO 800 is far more than enough, and for things like Orion (M42) ISO 400 is ample too, it helps boost the contrast ratio on brighter objects

Get yourself a Bhatinov Mask for each scope, I learned at the beginning how important it is to get crisp focus, and if you get the change to stay out for a long period of time, regularly check the focus, as the temperature drops, some focusers may move slightly

Simon

Hi guys,

Kinch, polar alignment is really easy on the LXD75. I have an app called "polarfinderpro" (android, not sure about apple) and it gives out the exact peak the scope should be at. Also, i completely agree on the Focussing, i am struggling to find a camera capture software for my D80 (the ones ive use do not allow bulb to capture longer than 30 seconds. I know, weird, right).
Thanks for the advice though, I'll keep trying to improve.

Simon, could you explain to me what drift alignment is. I'm not familiar.
My procedure at the moment is as follows:
1. Take out the scope and level it using a spirit level. (maybe this is the problem)
2. Polar align using the app mentioned above.
3. Use a Bahtinov mask to focus.
4. Then use 3 star alignment in Autostar on the scope, etc. etc.

As for the Bias, darks and flats, darks were good, flats were way to over exposed (I used a T-shirt and a lamp, cheap but supposed to be effective).

Wow that is an ingenious idea Simon. I will try to put that into practice. But am I correct in saying that that only works ive your light imaged are 300 seconds?

I really appreciate your advice guys! Google does not come with this kind of knowledge and experience

Clear Skies,
John