500D + Carl Zeiss Jena 2.8 135mm, first light, M31

[cuivenion]

Took this last night, my first night out in a while. It's my first time using a DSLR and I made a few schoolboy errors, like not covering the viewfinder and and not adjusting weights after going past the meridian. Taken with a Canon 500D with a Carl Zeiss Jena 2.8 135mm at F5.6 on a HEQ5.

50 x 180s Unguided

12x darks

20 x Flats

20 x Bias

Stacked in DeepSkyStacker and processed in GIMP 2.9.5. Any criticism welcome.

[MartinB]

Well done with this.  Nicely framed, was this cropped?  You have got quite a bit of the outer nebulosity and the dust lanes are showing well.  Great first light!

[cuivenion]

Thanks Martin, I have cropped this image. The corners were showing distortions even at F5.6, and also I didn't perform a meridian flip and the galaxy went off center, probably due to a sudden weight imbalance. I'm not sure sure if the severe chromatic aberation is due to the lens or maybe I over exposed? It's very noticable in the larger resolution picture and gives the whole image a reddish look. All that being said I'm still happy with it and its the best image I've got yet. Wouldn't mind a bit of constructive criticism though lol.

[Tommohawk]

Yes - I think that's very nice! The core isnt blown out which can be a problem.

Not sure quite why the colour seems a bit too orangey on my screen. I hope you dont mind - I had a bit of a twiddle with it... do you think its maybe better? Maybe not! Changed the colour balance and made stars a bit smaller.

 

[michael8554]

Nice start.

Regarding the noise, I have a 500D too, so would guess you had ISO at 1600 ?

Try 800 with longer exposures, but that might be too much for your unguided mount.

Stars have red halos, which might be a DSS artefact, or lens CA.

Here's my tweak, I've tried to remove the green speckles and minimise the red halos, but the galaxy isn't as good perhaps:

 

[cuivenion]

16 hours ago, Tommohawk said:

Yes - I think that's very nice! The core isnt blown out which can be a problem.

Not sure quite why the colour seems a bit too orangey on my screen. I hope you dont mind - I had a bit of a twiddle with it... do you think its maybe better? Maybe not! Changed the colour balance and made stars a bit smaller.

 

Thanks Tommo. Yes thats definitely better. It was was to orangy on my screen too. I'm not very confident with messing with colour balance and I set DSS to align the colours automatically. I had my 500D WB set to daylight, but I thought that was OK. Maybe its the lens.

[cuivenion]

11 hours ago, michael8554 said:

Nice start.

Regarding the noise, I have a 500D too, so would guess you had ISO at 1600 ?

Try 800 with longer exposures, but that might be too much for your unguided mount.

Stars have red halos, which might be a DSS artefact, or lens CA.

Here's my tweak, I've tried to remove the green speckles and minimise the red halos, but the galaxy isn't as good perhaps:

 

Thanks Mike. I can see what you're saying about the noise but this version is a bit to stark for me. I was using ISO 800, but it was a warm night and the sensor was between 23 and 26 degrees. Maybe thats why the noise is so high. I'm going to give this another go. I do tend to rush out an image, I'm going to have to learn to take my time and be patient.

[Tommohawk]

I don't think the lens would cause that colour cast. Have alook at the RAW files - if they look orangey then its nothing to do with DSS. I always have the white balance set to auto and that seem to work. Mines been modded so perhaps may behave differently. 

Main thing is if u use raw the data will be there somewhere!  

[cuivenion]

Just now, Tommohawk said:

I don't think the lens would cause that colour cast. Have alook at the RAW files - if they look orangey then its nothing to do with DSS. I always have the white balance set to auto and that seem to work. Mines been modded so perhaps may behave differently. 

Main thing is if u use raw the data will be there somewhere!  

Don't worry I make sure I use raw! I've just tried stacking in Astroart(demo) and the red CA in the stars seems to have disappeared. I'll keep at it. I'll try setting the white balance to auto on my next attempt. Thanks for the comments

[cuivenion]

Well I've spent the afternoon on it, and I think this is a nice improvement. Quite happy with this:

[cuivenion]

Last attempt for now. I've deviced to use the output file of DSS with adjustments embedded as it seems to colour correct quite well. I just saved as a 32 bit integer TIFF and then made some more adjustments in gimp.  It would be great if I could get DSS to do auto colour balance without it also stretching the data:

Looking at it I may have made the background a little to dark but I didn't clip the black point. I am wondering why there isn't more colour in the stars. I'm guessing I must have over exposed.