Photographing Comets

[phobos27]

Hey everyone!

I was just wondering how to photograph comets with an AZ-EQ6 mount. Comet Lovejoy is looking pretty good this month and I have tried photographing similar comets before but having the comet trail... Do I need any special equipment or anything of the like in order to get the stars to trail and the comet to not?

Thanks :)
Nick

[batema]

Hi Nick,

I have done it once where I had a real go at it. I took a series of exposures using a 770mm focal length William Optics and using a DSLR. I used Deep Sky Stacker to stack two images, firstly the stars as I was guiding on the stars. The image came out nicely except the comet had streaked. I then tried to stack the images using the comet and had success with this but the stars in the back ground were trailing. I then in photoshop put the two images on top of each other and I think it is Masking rubbed so the bottom image came through so I ended up with a nice star field and lovely green comet. I loved it. I also googled photographing comets and a heap of advice was found.

Good luck

Mark

[jakob]

I think registax has a comet option.
But I'm no expert.
I like your image, nice colour.

[algwat]

Try this,
since the comet is doing most of the moving.
Make your exposures duration as low as possible so that it does not streak.
The stars should also be points if your are guiding. Then take as many image as your can as the comet cross the centre of your fov.
If you can the register al your images on the stars, you will have only the comet moving. Then try to make the a registered image on the comet position. I use imagej to process my images, can do a region of interest selection that can be aligned to a first frame location. Works for me.

And visa versa , if you can set your guiding speed to match the comet movement, once you have it centred . The comet data should be good, and then who cares about the star data...8).

Kind regards, Alan.

[sil]

All my comet shots have been either handheld or on camera tripod. I always try for exposure of the comet, basically longest exposure time before stars streak. I recently reprocessed my old comet shots and got significantly better results. I used PixInsight's comet alignment feature to align the shots on the comet, the stars then either streak or disappear depending how I stack. Its significantly better than using the other alignment options and gave me faint tails I couldn't reveal when i originally processed the shots. The hard part is finding the comet in the shots to mark for the alignment.

[Flugel88]

Just a quick question! Can comet photo's be processed when using Mono camera's in LRGB?
I attempted this once with my asi using 2x30sec subs for each and i couldn't work out how to get it all to stacked and aligned for each colour using DDS and Photo shop.

[algwat]

yes color from lrgb can work.
The stars will be in three colors.
Align the frames directly on the comet only.

regards, alan.

[phobos27]

Hey everyone

Thanks for all the repsonses! Looks like there are several ways to do this. I already only take short 30 seconds exposures as these are the longest i can get with my camera. I also do not have a guide scope to fine tune the guiding. So with that in mine. When i am stacking the image, how can i only allign it on the comet and not on the stars. (I use DSS) Is there another program to do this for free?

Finally, does anyone know how to adjust the speed at which your mount tracks at to match the comet. If so, where can i find the speed of the comet?

Lots of questions but any help would be great!

[Solitarian]

DSS works fine,


http://deepskystacker.free.fr/english/technical.htm#cometstacking

[cometcatcher]

Hardly anyone tracks on the comet anymore. We usually take lots of short exposures before the comet trails and stack them. DSS will stack on the comet if a file is selected and the comet icon on the bottom right is clicked, but you have to do it frame by frame.

As mentioned there are many stacking options. Most people seem to like both comet and stars to be still, which usually means a dual stack and mask in photoshop. I totally suck at this technique though. I don't mind still comet and trailed stars myself, unless there's a conjunction. I think this method brings out the most comet detail.