Sub comparison with SW LP filter

[Spikey]

I had my first succesful attempt at autoguiding last night and managed 10 min subs. Quite a lot of LP from the railway over to my East where these subs of M31 were taken.

I started out without any LP filter 10 mins at ISO 800

and the with the addition of a Skywatcher 2" LP filter attached to the end of the DSLR extension tube, a quick re-focus and off again for another 10 min sub at ISO 800

Quite a difference !

Just thought I would share this as it's the first time I've used the filter.

I managed to get about 10 x 10 min subs @ ISO 800 but no darks or flats as the battery on my camera gave up and the mains adapter refused to work. At least I got the dew straps working !

The final result as below with my very poor attempts at processing which is significantly spoiling the end result but the learning curve is quite steep !

[todd8137]

i would not say that was a bad result the day i get a pic like the bottom one i will leap of my chair

[FraserClarke]

Very nice.

It would be interesting to see the difference in background level between the two images in numbers -- can you measure the average background for each image??

[Spikey]

Thanks for the comments, it was my first attempt at guiding and only my second attempt at a DSO. In fact the first was M31 as well.

The final picture came out like this here

http://stargazerslounge.com/imaging-deep-sky/158301-first-guided-dso-m31.html

I don't know how to measure the background level - any pointers ? and I'll gladly measure it.

The filter does look like it's doing the job though, the exposures were literally taken one after the other.

[PhoenixRising]

Well your guiding looks spot on

[FraserClarke]

I don't know how to measure the background level - any pointers ? and I'll gladly measure it.

Depends on what software you're using. Easiest is maybe to look at the histograms of the image and see where the peak is -- that should be the mean value of the image, which will be a pretty good approximation to the background level.

[Black Knight]

Spikey, which scope did you take these shots with?

[Spikey]

Cheers Phoenix, must be the guiding rings !

Andy it was the ED80 Pro.