Whilst I had my Celestron 102 SLT set up the other week I thought I would quickly have a go at M51. It wasn't the best conditions with the moon being up but I thought I would see what I could get.
I was quite pleased with the result (you can "click" on the image to see a full-size version). This a combination of 10x30s exposures at ISO 1600. This is a rotated and cropped version of the full image and I have displayed it this way as I wanted to compare it to another similar image that I took in 2016:-
This was also 5 minutes in duration using the same telescope but on Celestron's alt-az mount rather than the HEQ-5. I think my new image is better in that it is much sharper and shows considerably more detail in the spiral arms of the galaxy. I reckon this is due to the better mount and better focusing.
The only thing that I am not happy about is that in my new image the colour of the galaxy is a bit orangey brown when the spiral arms should be blue/white. However, considering that I took this in moonlight I really think there is a vast improvement (even the background noise seems less). I don't think there is a colour cast that has caused the orange colour as the background is pretty neutral (i.e. close to grey/black). In the older photo there is more of a strong green cast in the background.
All text and images © Duncan Hale-Sutton 2023
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