How to shoot Comet Lovejoy

multiweb (Marc) · #1 24-12-2011, 09:44 AM

Need a bit of advice on how to go about taking a pic of it. I've never done anything like that so a few questions that come to mind. I intend to shoot on a tripod with a SONY NEX-5 tomorrow morning. Is a tripod ok or do I need to take the mount and track? I have no idea how faint it is and how long I'll have to expose for. Thanks heaps for any pointers.

mithrandir (Andrew) · #2 24-12-2011, 11:21 AM

Marc, 30 sec unguided should be OK as long as you have a short focal length set. 50mm seems to be the longest that will keep it all in frame, and that's getting to be about to limit for 30 sec unguided. Beyond that a barn door would be sensible.

I have an 11-16mm f/2.8 and 16mm at 30 sec plus judicious cropping should work. The next lens up is only f/3.5

The view over the pool and the house, through the trees is in the right direction. At 23:00 the sky was almost clear. Set the alarm for 03:00 this morning, and it was pouring. Typical.

multiweb (Marc) · #3 24-12-2011, 11:40 AM

Thanks Andrew. I had a look back at the multitude of shots after I posted here this morning and checked the ISO and exp times. I see some did guide and even stack. I guess the comet is going to be away from the sun soon but still visible for a while so there will be other oportunities to do guided shots from dark locations. It's still in the morning sunrise right now so it might be time to find a nice skyline SE and shoot wide while it lasts? I'm doing the drive tonight at 2:00am with my daughter to Crago at bowen mountain and I'm hopeful the eastern horizon will be reasonably clear.

Mariposa (Amalia) · #4 24-12-2011, 05:10 PM

I suppose it all depends of what you want to achieve and how much yu are willing to work: up to 20 sec it worked fine with just a tripod and 50 mm lens at the lowest f stop you can go. I see that many have been taking single shoots, which worked fine. Obviously the super detailed ones are the result of tracking for longer exposures.
You can experiment with different ISOs and shutter speed, the main point is that you do it early, as soon as the predawn lights come, the comet fades very quickly.

RobF (Rob) · #5 24-12-2011, 05:16 PM

Yes, you need to be setup and shooting from 3am Marc.
I shot 30sec f/4 with my nifty 50 for 30 secs, ISO 800 on the 450D. Grainey until the sky lightened a bit and showing fair degree of streaking.

Ideally some tracking would be nice of course, but most of us happy just to see a glimse of it through the wet season weather across Eastern Australia currently.

midnight (Darrin) · #6 24-12-2011, 05:23 PM

My only regret of this morning Marc was not getting to my spot early enough. As Rob says you really need to be fully on the go by 3AM. I setup at 3:15AM and over the next 15-20 minutes, I rapidly started losing contrast.

Good luck!!!

BTW, DSS stacked 7 frames for me at ISO1600 and 15 sec exp with minimal artefacts. 35mm lense used.

Darrin...

Karls48 (Karl) · #7 26-12-2011, 11:59 AM

You need really big Canon

gbeal · #8 26-12-2011, 12:19 PM

I reckon if you have the ability to track without going overboard, do that. My 10 second shots tracked (not guided) were fine, and would think that 30 seconds etc would be as well. Like has been said, depends.
I used a zoom at about 35mm, ISO1600, and ten second exposures, wide open.
Gary

multiweb (Marc) · #9 26-12-2011, 01:20 PM

Thanks for all the suggestions. I got up 1:00am drove to Grago and started a timelapse 10s ISO 12800 until dusk. Not happy. Very bad choice of location in hindsight. Off to a dark site within the next two days and track at 50mm FL. I want some of what scott's got (tornado).

Timelapse here.

renormalised (Carl) · #10 26-12-2011, 01:31 PM

Need a clear horizon, Marc...get away from lots of trees. Nice timelapse though

erick (Eric) · #11 26-12-2011, 01:53 PM

Well - find a place:- 1) without cloud, 2) with a clear horizon and 3) without light pollution

hotspur (Chris) · #12 26-12-2011, 03:07 PM

Quote:

Originally Posted by midnight

My only regret of this morning Marc was not getting to my spot early enough. As Rob says you really need to be fully on the go by 3AM. I setup at 3:15AM and over the next 15-20 minutes, I rapidly started losing contrast.

Good luck!!!

BTW, DSS stacked 7 frames for me at ISO1600 and 15 sec exp with minimal artefacts. 35mm lense used.

Darrin...

How did it turn out Darrin? be interesting to see a stacked image the way you have mentioned,Ido not think I have seen too many stacked images of this object.

midnight (Darrin) · #13 26-12-2011, 03:18 PM

Quote:

Originally Posted by hotspur

How did it turn out Darrin? be interesting to see a stacked image the way you have mentioned,Ido not think I have seen too many stacked images of this object.

Not too bad Chris. The key seems to be short exposures to avoid excessive trailing.

This was my 1st attempt

http://www.iceinspace.com.au/forum/s...ad.php?t=84605

I overlaid the terrestrial section at the bottom as DSS will naturally blur the bottom as it adjusts each frame.

Cheers,
Darrin...

multiweb (Marc) · #14 29-12-2011, 10:41 PM

Got some time lapses at last. I was surprised how faint it got just in a matter of days. This was taken from a very dark site. As dark as it gets really approx. 50km north of Orange. See annoted picture. Still you can see it got very faint very quick.

Time lapse A [10MB]

Time lapse B [2MB]

I have two time lapses because the wind knocked my tripod before the end. So the last time lapse is from another location until dawn.

You can see me on and off the main scope doing polar alignment then guiding 5min subs with a 50mm lens which I'll post later. I got four panels out of 5. The wind got the best of me in the end and I couldn't get the head of the comet in the high-res mosaic but I've got a nice tail.

Still got some decent timelapses. Will try to stack and also make some star trails.