How to image deep sky objects?

[asteele3]

How would I go about imaging dso's?

Say I wanted to image the lagoon nebula. I have a Canon Eos 1100d attached to a Celestron C8 XLT on a Heq5.

My limit is about 20 second maximum worth of exposure time because the image becomes too bright after that.

I know my scope isn't the perfect scope for imaging DSOs because of the F10 ratio but as it is an 8", surely I should be able to get some images where you can see the fuzzy nebula?

[OzDave]

When you say the image gets too bright after 20 secs, do you mean the background (from light pollution)?

To get much in the way of detail from something like the lagoon nebula, you are going to need longer exposures. At least 2-3 minutes, and then you'll need as many of those as possible. At least an hour in total, but it wouldn't be uncommon to collect 10 hours or more of data.

Basically the longer you can make your exposures and the more of them you have, the better the result will be.

For combatting sky brightness, yoy might want to consider a light pollution filter of some sort.

David

Sent from my iPhone using Tapatalk

[dmahon]

You should be able to take pictures at least five minutes long with a DSLR (if your polar alignment is good enough or if you have guiding) even in the middle of a town. It might appear bright, but you can process that out. A filter can help if you really are in the middle of a light polluted area.

[Viv]

moved over to imaging, you should get some more help here.

[asteele3]

Thanks! And yes I mean the Background appears bright when I zoom in on the computer I can see a couple of stars but that's it. Although I'm basing this post on last night where it was 70% cloudy and I was trying to get an image of the big dipper but I must admit it wasn't really clear at all. I suppose when there's clouds, it will make my image a little bit brighter because the clouds might emit light? I suppose I'll just wait and see how I get on tonight. Both my neighbours have gone on holiday so I won't get light from them and I have a south facing garden with a massive open park at the back so no lights will come from there. tbh, I think I'm fairly lucky with light pollution, I mean, I did have all the lights on in my house last night, so I guess that's a factor as well lol.

I'm not expecting good images tonight, just so I can see a few stars in the images and maybe get a fuzzy outline of the lagoon nebula?

If not, are there any other nebulas or galaxies that will be brighter and might be easier to photograph?

Thanks.

[Gina]

The Lagoon Nebula is quite large so you might not get it all in. However, the main part should nearly fill your frame as I calculate it. I think you should be able to get it, even at f10 - it's brighter than a lot of nebulae. Only problem might be that it's quite low in the sky so you migh have light pollution problems if there's lights in that direction. I use an Astronomik CLS clip filter to stop LP - not cheap but very effective. You don't say if your 1100D is modded for the full visual spectrum. If it isn't you'll need something like 4 times the exposure as the Lagoon Nebula is a strong Hydrogen alpha emitter which is a deep red. If you want something easier try M13 a star cluster. This would be much better suited to an nmodified DSLR.

[asteele3]

Thanks Gina!!! Yes, I've seen the M13 and it looks like a reasonable target for tonight. I've done nothing to my camera it's unmodified. I thought the Lagoon nebula was quite high up in the sky according to stellarium? It's not too far from Vega I thought which is really high up? Anyway thanks for the information, very much appreciated!

[Gina]

Glad to help