[iceman (Mike)]

Originally Posted by StephenM

I like the second image with the foreground lights, Mike! Was the comet visible above those lights?

Cheers,
Stephen

Thanks Stephen. The comet was barely, barely visible naked eye. I glimpsed it only occassionally. It certainly didn't jump out at me.

Originally Posted by kinetic

Lovely image Mike,

Did you get a set of identical exposures that could stack?
Looks like the 40D does well enough anyway at 1600!
Nice job.

Steve

Thanks Steve. I did take a bunch of images to try and stack them, but I'm having problems with Deep Sky Stacker at the moment so haven't been able to stack them. I'll give ImagesPlus a go later.

The 40D is ok at ISO1600. It does have a "H" ISO mode which is ISO3200 I think, but it's extremely noisy and virtually unusable.

Originally Posted by gregbradley

Great shots Mike.

I think to capture these comets well with a DSLR you have to either:

use a tracking device
use a widefield really fast lens like you did and 30-60 secs
use super high ISO like 12600 or more and ICNR and hope it works out.
stack lots of shorter exposures to get the signal

I found this whole process kind of educational about what works with these sort of shots.

Looking at the viewfinder is also not a good guide to the final result. It doesn't show up star rotation which with this comet are all on the left side of the image and the right side stars stay pretty round.

For the next comet I plan to use a portable tracking device like the Losmandy unit and use a 5DMk11 or 111 if its out and high ISO and a few minutes and a nice fast wide lens.

Greg.

Thanks Greg - you're quite right. I really would loved the 5D Mark II with a faster lens. I had to use my 17-70 rather than the usual 24-105, simply for the wider field of the 17mm, but also because the 17-70 is f/2.8 and the 24-105 is f/4.0 - too slow for astro shots like this (or timelapses).

There's been some great shots where it's a single shot of 30-60 seconds, but most of those were when the comet was brighter and had some nice foreground.
Most of the great comet-only shots were tracked and didn't bother with silly things like a foreground