Although it seems like an age now, I was on holiday not to long ago in darkest Norfolk, looking forward to some imaging. Typically, over my two week break I had two nights that we usable for imaging and one of those was lost to feeling obliged to give an interested party a guided tour of the sky!
My only real attempt was an image of M31. My original target of the Veil Nebula just proved too faint in what were still quite bright skies during August so M31 it was.
The image below was taken with a Nikon D7000 and consisted of 6 x 9 minute exposures. I had planned for many more but guess what? Cloud arrived!
I therefore decided to see, having taken darks and flats, how much I could stretch the original image for detail. Overall I was quite pleased. Its has some noise in it, but that’s really down to only stacking 6 frames. Photoshop really saved the day!
The original image, which even in Norfolk shows a hint of light pollution
And then with lots of level adjustment and enhancement…
So not maybe a silk purse but a big improvement over the original…..Photoshop is your friend
So why don’t the pictures want to display???
Looks like the image source is from your laptop – you’ll have to post the images elsewhere (e.g. Flickr or Photobucket) and link back to the image here. Alternatively, you can upload a file to this website, but it must be <500K in size.
Lets try again
We got pictures, but what happened to the quality?? Anyway, you get the idea
I get the idea, Rupert. And even that lower quality posted image is really awesome. I think the compression routine of your upload has skewered your details so I can imagine how much better your proper image is. Can you link to your flikr maybe?
Easiest way to share an image from Flickr in this forum (now that we have BBCode activated) is to go to Flickr and click on the “Share” icon. Then select “BBCode” and select the size of preview image that you want. Then copy and paste the code into a message on this forum.
“(url=https://flic.kr/p/oFWUHy)(img)https://farm4.staticflickr.com/3906/14891905626_e950173671_z.jpg(/img)(/ur)(url=https://flic.kr/p/oFWUHy)Perseid Cudham August 13 2014(/url) by (url=https://www.flickr.com/people/60867344@N08/]MikeMey67(/url), on Flickr” gives:
[NB: use  brackets and not () shown above… just copy and paste direct from Flickr]
Perseid Cudham August 13 2014 by MikeMey67[/url], on Flickr
Nice photo, shame your sensor is scratched. I managed to capture no scratches at all that night.
So third time lucky
M31 Unprocessed (stacked)
M31 9 web by astrograph ltd[/url], on Flickr
M31 web by astrograph ltd[/url], on Flickr
Images were taken with a Nikon D7000, APM 100/800 with Flattener, Guided. 6 x 9 minute frames, plus flats and darks. Stacked in DSS, processed in Photoshop
Oh thats so much more crisper. Lovely, and with so few frames to stack.
Some Questions, Rupert.
1. Going by the unprocessed image, there is some obvious light pollution. I know you have used CLS filter when in London, would it have helped to use it in Norfolk too or would it be counter-productive if there is dark enough skies?
2. It seems to me you might not have used the Nikon’s full resolution as the Flikr image is the same size (actually slighty smaller!). Is there an advantage to that to using lower res? I cant imagine that you had any reason to crop it with the telescope you have and with a flattener…or am I losing perspective by the huge scale of Andromeda!?
I took this mid August and it was still fairly light. By the time M31 was high enough to image and it was dark enough, I then only had about an hour to get anything before it was past the Meridian and more light pollution arrived. Norfolk is normally really dark but during August you get kids camps with floodlights and that is a problem.
In London I would have used the CLS, because after about 30 seconds you just have an orange cast. Unfortunately a CLS needs about 50% more exposure time. This would have meant a 15 minute sub. I did not have the luxury of that so went with what I could get. 9 minutes is about the minimum to get the outer detail. Its all a balancing act.
Had the nights been better I would have gone back and added more frames, ideally to get 30 (which needs 3 hours) and tame the noise, however that didn’t happen. In addition to do a proper job I needed some really long and shorter frames so we could make an HDR image.
If nothing else this highlights the benefit of a colour camera to a mono one. With a mono, I would only have got two frames (LRGB x 2 = 8 exposures)!
The image was full frame on the Nikons APS sensor. I did crop very slightly to produce a 10x15cm format and its re-sampled for 96dpi for the . M31 is a big object. It actually does not fit on an APS sensor at 800mm focal length. On a Canon APS it would have been heavily cropped. A 700 or even 600mm would have been better, but even so you need to put M31 diagonally to fit. I had actually setup to image the Veil Nebula but pollution just made that unrealistic so re-tasked to M31.
Nice photo, shame your sensor is scratched
I could take serious offence at that kind of remark you know 😉
That makes perfect sense, Rupert, thanks for explaining.
I only just got the joke about the scratch on the sensor, good one!