Ngc 5247

[graham.hobart]

Hello, this is four hours and 15minutes of 300sec (five minute) subs with darks and bias frames. Canon 5d mark II and RC 10 with it's original focuser.
I have great difficulty controlling noise - the camera temp was ranging between 27- 31'c even though ambient was 6'c to 3'c.
It is cropped as I have still some collimation issues to address.
Thanks for looking.
Graham

[SimmoW]

A heap of dedication on this one, good work. Looks like you'll need to get a CCD soon.

[Regulus]

Nice photo Graham.
Do u use the cameras Long Exp Noise Reduction or rely on software afterwards to deal with noise?

Trev

[graham.hobart]

HI Trev, no I don't use the in camera noise reduction -would make the subs even longer!
I just tried to post process (Star tools) it out but because the sensor temp is so high if you stretch it more you get horrible read noise every where.
Looking around for a CCD again now. Have an old style QHY which has the older style cooler control on it- I took a series with that camera and an 110mm refractor which I will put up to compare.

[cometcatcher]

So that's what it looks like with more data. I was shooting this one the other night. Good work Graham. Yeah a CCD would really make this one pop.

[rcheshire]

Hi Graham. How many darks?

[graham.hobart]

HI Rowland- I think I recall 30 darks and 60 bias frames - have not got any flats sussed for this scope yet - light box on order.
Another reason it may be noisy is that it was ISO 1600- first time I have shot at this ISO- usually aim for 800 ISO but when I started I was imagining I would only be able to collect an hour or so- due to weather clouds and Moon. If I'd have known I would have stuck to ISO 800!

[rcheshire]

That's a good set. I have been doing a bit of testing with Canon DSLR calibration frames. You could try darks only and leave out the bias and see how that goes. Not sure what you are using for stacking but sigma clipping should help. Pick your best sub as the stacking reference and don't calibrate the darks - leave the bias in. Hope that works - it did for me with a similar set of HOT 5DMKII frames, between 13 and 28C.

[graham.hobart]

These are good tips Row, will try that later tonight see how it goes.
Cheers
Graham
NB stacking in Deepsky Stacker