Trifid

Geoff45 (Geoff) · #1 10-09-2007, 04:44 PM

Here is a quick process of the Trifid which I took last night. Could probably be improved with more attention to the processing, which I'll get around to.

5 x 10 min lights, 23 x 10 min darks (camera kept working after I packed up).
Canon 350D, unmodified.
110mm refractor on GM8, autoguided by Toucam and PHD
Location: Ilford (near Midgee).
Geoff

Astroman (Andrew Wall) · #2 10-09-2007, 04:52 PM

wow thats alot of Darks, probably more than whats needed on the image. But wont hurt it much. Top stuff.

Geoff45 (Geoff) · #3 10-09-2007, 04:59 PM

Quote:

Originally Posted by Astroman

wow thats alot of Darks, probably more than whats needed on the image. But wont hurt it much. Top stuff.

Berry and Burnell in Handbook of Astronomical Image Processing recommend 5 times as many darks as lights and go into detail why. I must admit that I am seldom this diligent, but it's quite easy to set the camera with a remote control and let it chug away while u sleep

EzyStyles (Eric) · #4 10-09-2007, 05:15 PM

great shot geoff. if you crank the contrast a little higher, it will bring out more of the colours. im not so sure about taking 5 times of darks as light frames. you mean the other way around? 5 - 10 dark frames is plenty.

EzyStyles (Eric) · #5 10-09-2007, 05:21 PM

also note, the change in tempreture 23 x 10mins = nearly 4 hours worth of darks will vary dramatically hence it will not match your light frames.

Geoff45 (Geoff) · #6 10-09-2007, 06:08 PM

Opinions on the number of dark frames varies. Have a look at these sites:
http://www.imagetech-ontario.com/edu...flatbiadrk.htm
http://www.aavso.org/observing/progr...manual/3.shtml
both of which talk about Berry and Burnell's Image-times-five rule. I agree that there are problems with temp control, which is a lot easier with a cooled ccd than a DSLR. A lot of people suggest taking dark frames between each light frame so that things average out.
Geoff

skeltz (Rob) · #7 10-09-2007, 08:14 PM

yes i agree go a bit easier on the darks ,maybe a bit more time on the image itself,other than that your on the right track
cheers rob

Ric · #8 10-09-2007, 09:14 PM

Nice image Geoff.

Cheers

Geoff45 (Geoff) · #9 11-09-2007, 11:47 AM

Quote:

Originally Posted by EzyStyles

great shot geoff. if you crank the contrast a little higher, it will bring out more of the colours.

Here is the same image with an s curve in PS to tweak the contrast.