M3 with a Canon, a firstlight thingy (pt2)

[BlueAstra]

After my first shot at the moon with the Canon 1000d fresh from its wrapping (see Imaging - moon), I moved on to M3. Not having gone through all the 'how to' threads yet I just went straight in with a 60s exposure, after focussing on Arcturus. Controlling the camera remotely from a laptop is great.

Now I know why people use guide cameras. Not sure the tracking system on the scope is accurate enough for really long exposures.

Anyway, must now learn how to do it properly, and what this Deepskystacker thingy is all about. Anybody know what 'white balance' should be set to for astro photos? Also a pointer to a 'Canon 1000d/450d astro setup' thead would be welcome.

[Sam]

That's a great first DSO! One of the key things to reduce star trailing when you don't have an autoguiding set up is to ensure the polar alignment is bang on - drift alignment will do the trick. Depending on the mount this will enable you to go to 90 or even 120secs without out too much trailing. I hope you don't mind but I had a wee go at brightening it up and a dynamic background extraction in PixInsight. You're well on your way!

Sam

[BlueAstra]

All my photos are now on the way to you Do you have a reference for the software you used? It looks useful.

[Sam]

Here's the link:

PixInsight — Downloads — PixInsight LE

If you're using vista it might be worth running it in XP mode. It a great app once you get your head around how to use. There's some quite good tutorials on the website. The best thing is it's free!

Sam

[RichieJarvis]

As Sam says, your on your way

The next step is to take a number of 60 second exposures and stack them using the DeepSkyStacker you mention.

Basically, imagine it like this:

Signal = stars, the object you want

Noise = everything else - its (mostly) random

So, you want more Signal, and less Noise. Another way to say this is to say increasing the Signal to Noise ratio, or SnR.

Because the signal in your image is constant (when you line up the stars in each sub together) but the noise is random, you will end up improving the signal with each additional sub you stack - things get smoother in the image.

You can't cheat and just use the same sub multiple times btw unfortunately

Heres an example - stacking the 4 images on the right becomes the left - you can see that the 'stars' become alot easier to pick out - image what it will do with 10 or 20 subs!!

Cheers,

Richie

[BlueAstra]

Thanks for the explanation. Thats really useful. Can't wait for the next clear night to have a go!

My first shots had a very purple background. I put a LPF filter on which reduced it a bit. Wasn't sure whether it was the WB setting. Do you know what the best white balance setting is for the camera at night?

[Les Tilly]

I believe its Daylight setting in your camera and in DSS you should set DSS to (in Camera white Balance) if I recall, and shoot in RAW mode

Regards Les

[BlueAstra]

That's a great first DSO! One of the key things to reduce star trailing when you don't have an autoguiding set up is to ensure the polar alignment is bang on - drift alignment will do the trick. Depending on the mount this will enable you to go to 90 or even 120secs without out too much trailing. I hope you don't mind but I had a wee go at brightening it up and a dynamic background extraction in PixInsight. You're well on your way!

Sam

I wonder if you could just detail what commands you used in the software, and what you adjusted, to get me up and running.