Cloudy nights = more processing...

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

Rgds

Rupert

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

M31 Unprocessed

M31 Processed

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.

e.g.

"(url= https://farm4.staticflickr.com/3906/14891905626_e950173671_z.jp g" target="_blank">https://farm4.staticflickr.com/3906/14891905626_e950173671_z.jp g"/> (/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, on Flickr

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, on Flickr

M31 Processed

M31 web by astrograph ltd, 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!?

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.

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!

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