Comets with a DSLR

[frugal]

I want to have a crack at photographing some of the comets that are currently in the sky. However I do not have a tracking mount, I just have a photograhy tripod and a DSLR.

Do I stand a snowballs chance, or should I just stay in bed tomorrow morning?

At 300mm I am looking at about 1.5 second exposures before everything moves in the frame. At 100mm I would be looking at 4 seconds. Is this remotely enough time to capture the comets?

Although at the moment everytime I check MetCheck the cloud cover for 6am tomorrow goes up another percentage point ;( It has been saying 0% fpr the last 5 days, now it is up tp 3% and climbing, ao it might all be a moot point.

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[Astrosurf]

I've only used a tracking mount but this looks like a jolly site! I'm sure someone will be along soon to give specifics.

http://waitingforison.wordpress.com/comet-photography/

The shorter the lens the longer the exposure you can use, and more forgiving, but also the smaller the subject!

Alexxx

[Andy_E]

Depends on how bright they are... at the moment Lovejoy and ISON may be a little dim... but definitely worth a try. This was my effort at Panstarrs earlier in the year. Single shot, ISO1600, 1.3 sec exp, 400mm @ f5.6. It can be done!

[Astrosurf]

Lovely shot. And yes, of course, it depends on their brightness!

[frugal]

Right, the MetCheck astronomical forecast still claims that it is going to be clear pre-dawn tomorrow. I am going to have a crack at it. I am just having a wee dram, then I will pack the car with the camera, tripod, and maybe the telescope so that I can get up at 04:30 and drive over to a local iron age fort that should be high enough to get a good view of the horizon and little light pollution. Regardless of what I catch in the sky, I have to finish at 07:00 so that I can walk back to the car, change into my suit and get on a train for a meeting in London

[Astrosurf]

Good grief! And good luck. I'll be at the site at about 4am so will get up at 3:30. Then to work at 7am too, but an easy 45min drive!

[Andy_E]

Good luck! Remember if your subs are fairly good (with little star trailing) you could always try stacking a few to tease out a bit more detail in the tail.

[frugal]

Well, it looks a bit cloudy out there and the dog is giving me a look that clearly says she things it is far too early to be up, but I am going to give it a go. Wish me luck.

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[Astrosurf]

How did it go? I gave up on guiding because of the clouds, and I couldn't have long exposures as it was so light. Flaffed around a bit but might have enough for a movie if nothing else.

Let us know how you got on.

[frugal]

It was very cloudy. There were breaks in the cloud cover, but never in the direction of ISOn and Enke. Even at 06:30 as the sky was brightening and the rest of the sky was clear, there was still a thick bank of clouds over just that one part of the sky.

On the othet hand I got some great shots of the moon surrounded by clouds that I am going to try and HDR, and some cracking sunrises. I will have to see exactly what I got this evening.

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[Astrosurf]

I'm glad you got something for your efforts! I'm looking forward to seeing the images.

[frugal]

To add insult to injury, right near the end as the sky was brightening I could see Spica just above the clouds taunting me. You could almost hear it saying: "if there was a little less clouds the comets would be just below me..."

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[Astrosurf]

There's still hope. It'll be around for a while yet. Let's just hope it survives its close pass of the sun!

[Physicist13]

the data will be there even on v short exposures. take as many pics as poss and stack/add. its a myth that you need to have signal to noise >1 on any sub.

[Guy Wells]

I'm stacking

..

[glowingturnip]

any thoughts on max exposure time for the comet on a guided mount ?  It'll still be moving relatively fast compared the stars I guess.  Also, just whack up the ISO ?

[smudgeball]

Hi

A friend of mine got a 20 minute sub of comet lovejoy a few weeks back (Galloway Star Camp), he doesn't visit SGL that much so I'll mind him on to pop his image on here.

He can let you know his settings.

I have a copy but I'll let him post.

Regards

Neil

[Physicist13]

max exp will depend on lots. Mainly FOV ie focal length. can calc how much it will move given its predicted path and how well u are polar aligned etc but a bit comp! Trial an err is best! but "window of opportunity" may be short Upping the ISO is really only to get to a better SNR performance of the camera (the noise doent exactly scale with the gain). Opt for DSLR is usually 800-1600iso but it varies. again as capture time may be limited you may have no choice but to increase iso and just live with the noise.

[frugal]

I have been having a look through the photos I took this morning. I ended up with a bunch of stylish landscapes and sunrises rather than the comets I went out for:

The moon through the tree:

Sunrise over the valley:

Although I did not get much stargazing done, at least I was not being rained on like the people over the horizon:

The cloud over resolutely stayed in the one area that I was hoping to look at. The closest I got to ISON was to see Spica poking up through the clouds:

Having got up at 04:30 it was nice to see a beautiful sunrise:

However when I was going through the photos I used to focus the camera I kept seeing the same plane on the frame... in the same place... oh hang on!... Yup, I was trying to focus the camera on Mercury not a star and I happened to get 2P/ECKNE in the frame... Doh!... The galling thing was that these were my focus frames as I thought it was higher up in the sky, so I did not notice it or I would have taken more frames:

It isn't a great frame, it isn't even a particularly good frame, however I am chuffed to bit to have taken it.

[ScopeDog]

As Neil said, I took a couple of images of Lovejoy at Galloway recently. I was using a 1200mm FL SW Skyliner 200 on top of an NEQ6 with PHD guiding and imaging with a modded EOS 450D.

It was my first time imaging a comet and I didn't really know what to expect. I did a range of exposures starting at about 5 minutes as I wanted to bring out as much of the tail as I could, but I noticed that the nucleus appeared as a short bright line. The surrounding stars were nice and round, so the guiding was okay. It suddenly struck me that I was seeing the comet moving against the background stars over that short time period. I really didn't expect it to be moving that quickly! Stupid of me really . Bit of experimenting showed that around 3 minutes exposure at this focal length and ISO800 gave a pleasing result in terms of colour without too much nucleus trailing.

I decided to throw caution to the wind and try a 20 minute sub on the comet. Never guided a single sub that long before so thought it would be a wash out, but I fancied a chat and a dram with the guys along the way so set it going and walked away. The result is below, along with the 3 min for comparison. I was quite pleased (and the guiding seems pretty solid too   ).

Tom

[glowingturnip]

thanks, will have a go.  Am hoping it survives perihelion, have a small trip on 9th Dec and will get to play my scope then (also hoping it's not cloudy of course)

[glowingturnip]

thumbs up for the moon thru trees and rain on the horizon photos btw !