Rosette Nebula NGC2237

[Carole]

First image of 2012, done over 3 nights all 800 ISO, Modified Canon 450D CLS filter
13-1-12 300 x 21
15-1-12  300 x 23
16-1-12  300 x 40
Total of 7 hours, my longest image to date.

Captured in APT with dithering in PHD/QHY5
Processed in DSS and PS CS3

Link to larger file:
http://gallery.orpington-astronomy.org.uk/albums/userpics/10047/Rosette_7_hours_13th%2C15th___16th_Jan_2012_ED80_.jpg

[The Thing]

That is jolly good Carole, your getting really good results. I like the range of tones you've produced.

[MarkS]

Carole,

That's an excellent result - especially given your light pollution.  The CLS filter was definitely doing its job.

It's a nicely processed result.

I'm also glad to see you adding together the results from successive evenings - it really is the only way to get enough data for outstanding images.

Mark

[Fay]

That has come out very nice Carole a lot of hours!

Fay

[JohnP]

Very good Carole - especially from Bromley - Small gradient Left to right but other than that looks brill - you must be chuffed after such a long exposure time..

[Rocket Pooch]

Very nice.

[Jim]

Really nice Carole

[Carole]

Wow, lots of nice replies, thanks every-one. 

I have determined to do long hours of exposures this year to try to reduce the noise, and am also learning that some objects are not suitable from Bromley. 

I haven't actually started using my DSLR coolbox yet as the weather is cold, and it's a bit of a fag to set up, plus I am not sure how safe it is to lower the temperature of a DSLR, opinions gratefully received on this.

Carole

[mickw]

Very nice Carole

You need to crop out the misalignment though (I presume from separate nights) top and right edges, those edges show up much darker.  Or tweak the black point.

[MarkS]

... I am not sure how safe it is to lower the temperature of a DSLR, opinions gratefully received on this.

What makes you think it's possibly not safe?

[Carole]

What makes you think it's possibly not safe?

I think it was something that Olly said on anotehr forum, about some-one he knew froze their DSLR into a coma.

So looks like you think it will be OK then Mark.

You need to crop out the misalignment though (I presume from separate nights) top and right edges,

Blimey Mick - you've got eyes like a hawk, I didn't even notice that.  Yes it was from doing it over three nights, but I thought I had cropped it out already - obviously only cropped out the worst bit - duh.

Carole

[MarkS]

With regard to cooling,  the CCDs in Canon cameras are far less noisy than the CCDs used in some cooled astro-cameras (e.g the commonly used Kodak KAF-8300 chip) so you really don't need to emulate the same ridiculous lengths they need to go to for cooling the chip.

I reckon an ambient temperature of -10C to -15C (which would cool the CCD to around freezing point or slightly lower) is quite adequate.  If you wish, you can test it yourself by taking dark frames at various cooled temperatures.  The camera (and Lithium Ion battery) should operate perfectly well at such temperatures.

The only thing that might potentially cause a problem is condensation inside the camera body, on the circuit boards.  This could cause a malfunction - either temporary or permanent.  If the condensation were to freeze, e.g. on the shutter mechanism then this might also cause a problem.  I would recommend that you store the camera in a dry sealed box containing dessicant - this will minimise this possibility.

Mark

[Carole]

Thanks Mark, I have already tested the DSLR coolbox using darks, and it does bring the temperature down about 8 degrees, but I was doing it in a room that was a lot warmer to start with.

I think I will just give it a "go" and see what happens.

Thanks

Carole

[Mike]

Really nice Carole.

[Carole]

Many thanks Mike.

Carole