Subscribe to Flamsteed via Email

Enter your email address to subscribe to this website and receive notifications of new posts by email.

Join 1,779 other subscribers

Home Forums Observing and Imaging Group Cloudy nights = more processing…

Viewing 13 posts - 1 through 13 (of 13 total)
  • Author
    Posts
  • #7910
    Astrograph
    Participant
    Topics: 27
    Replies: 102

    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

    M31 Unprocessed

    M31 Unprocessed

    And then with lots of level adjustment and enhancement…

    M31 Processed

    M31 Processed

    So not maybe a silk purse but a big improvement over the original…..Photoshop is your friend

    #7911
    Astrograph
    Participant
    Topics: 27
    Replies: 102

    So why don’t the pictures want to display???

    Rgds

    Rupert

    #7912
    Mike Meynell
    Moderator
    Topics: 119
    Replies: 756

    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.

    #7917
    Astrograph
    Participant
    Topics: 27
    Replies: 102

    Lets try again

    M31 Unprocessed

    M31 9 web

    M31 Processed

    M31 web

     

    • This reply was modified 5 years, 8 months ago by Astrograph.
    • This reply was modified 5 years, 8 months ago by Astrograph.
    • This reply was modified 5 years, 8 months ago by Astrograph.
    • This reply was modified 5 years, 8 months ago by Astrograph.
    • This reply was modified 5 years, 8 months ago by Astrograph.
    • This reply was modified 5 years, 8 months ago by Astrograph.
    #7924
    Astrograph
    Participant
    Topics: 27
    Replies: 102

    We got pictures, but what happened to the quality?? Anyway, you get the idea

    #7930
    Tej
    Participant
    Topics: 39
    Replies: 597

    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?

    #7932
    Mike Meynell
    Moderator
    Topics: 119
    Replies: 756

    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.

    e.g.

    “(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

    #7956
    Astrograph
    Participant
    Topics: 27
    Replies: 102

    Thanks Mike

    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 Processed

    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

    #7958
    Tej
    Participant
    Topics: 39
    Replies: 597

    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!?

    #7963
    Astrograph
    Participant
    Topics: 27
    Replies: 102

    Hi Tej

    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.

    #7965
    Mike Meynell
    Moderator
    Topics: 119
    Replies: 756

    Nice photo, shame your sensor is scratched

    I could take serious offence at that kind of remark you know 😉

    #8026
    Tej
    Participant
    Topics: 39
    Replies: 597

    That makes perfect sense, Rupert, thanks for explaining.

     

    I only just got the joke about the scratch on the sensor, good one!

    #8055
    Sumitra
    Participant
    Topics: 21
    Replies: 233

    Rupert, these are amazing photos!

    I could take serious offence at that kind of remark you know

    Aww Mike… Chin up! It’s only just one scratch! You saw the state of my sensor? Now, I could take serious offence and a nervous breakdown! 😉

    Perseids Stacked Composite.jpg

Viewing 13 posts - 1 through 13 (of 13 total)
  • You must be logged in to reply to this topic.