M51 Rother Valley 9-5-11 DSC

[Carole]

OK the results of last night's imaging between 11.30 ish and 2.30am (in between clouds).  
6 day old Moon which had set by the time I got to the later subs.

14 x 4mins and 3 x 5mins plus darks flats and bias
Guided, cropped
SW ED120, EQ6 and Modified Canon 450D + CLS filter
(I tried with my single sub the previous night without a CLS filter and got a brownish sky).
Guiding doesn't look great, but the PHD graph was fine. 

Not brilliant, but I think this is the best I have done of this object to date:

[MarkS]

That's looking pretty good Carole.  The stars are a bit odd shaped and the colour balance is off (too brown) but you have a good signal to noise ratio and some of the very faint wispy stuff is beginning to appear.  There is a fair amount of detail appearing also.

Personally I would have not used a CLS filter for a galaxy in a darkish place like Rother - you would have got a cleaner result and a better colour balance in spite of the brown background (which can be subtracted).

Well done!

Mark

[Carole]

Hi Mark,

Thanks, I agree about the star shapes, not sure what has caused that as the guiding seemed to be OK including the graph.  

Personally I would have not used a CLS filter for a galaxy in a darkish place like Rother - you would have got a cleaner result and a better colour balance in spite of the brown background (which can be subtracted).

Yes I wondered about that, but being on my own, I didn't have any of my wise advisors to ask, so had to make a decision (trust me to make the wrong one!).  I'll take a look at the colour and see what I can come up with.  

Carole

[Carole]

Is this any better, or is it worse?

[mickw]

Background looks noisier but it's less brown.

[Fay]

Details there, Carole, not sure why colour is pink though. Have another process

[Carole]

not sure why colour is pink though.

I haven't done anything to it except reduce the colour.  I had assumed it was because of the Mod to the Canon.

Carole

[Carole]

Have reduced the colour a litle more and sharpened the image.  Not sure if this is better or worse.

[Fay]

Carole I think you needed at least another 20 subs, longer exposures, more like 300secs

[Carole]

I think you needed at least another 20 subs, longer exposures, more like 300secs

I agree I need at least another 1 - 2 hours worth of subs.

I normally do 300sec subs, however I had a conversation with Mike about the amount of noise I get with the DSLR especially in the warm weather, and he suggested I try shorter subs.  He did suggest 3min subs but I was a bit apprehensive about doing such short subs.  So my plan was to do a compromise with 4min subs for one hour and 5min subs for a further hour so I could compare the noise.  However the clouds beat me to it and I only got 3 x 5min (300sec) subs.

I am planning to try to get more at a later date, but I have to wait for a dark site as it's a waste of time in Bromley unless I just want to practice and in any case it is too high for the dome at the moment. 

Carole

[Mac]

Nice image.

take the darks at 4 & 5 mins, and then compare the noise,
the difference is that there is no light data on those just the noise, so you can see what you are getting.
and which ones are better.

Also turn off your image preview on the back of the camera, if you haven't already done so,
as this introduces a lot of noise.

Mac

[Carole]

Also turn off your image preview on the back of the camera, if you haven't already done so,
as this introduces a lot of noise.

I keep turning this off and if I turn the camera off at any point (i.e. for changing a battery) it switches itself on again and I don't always remember to keep switching it off, is there any way I can switch it off as a default or until I tell it otherwise?

Carole

[Mac]

I don't always remember to keep switching it off, is there any way I can switch it off as a default or until I tell it otherwise?

This might help with turning it off.

http://www.wikihow.com/Use-a-Hammer-Safely


Mac.

[Carole]