Question over Deep space Imaging

[Darien]

Hello everyone,

On the past deep space objects Ive done.. Ive noticed some people using DSLR like me doing exposures such as 24x300 ,and 17x 200sec both at the same ISO. My question is whats the differemce between doing that and just doing 4hrs of 5min subs? is it better to do it that way? Dose it bring out more detail in the image? Thanks all, Darien

 

Here's an example of what I mean.

 

 

[wimvb]

With a Dslr it is very likely that 10 minute exposures will overexpose (bloat) stars. That's why you would do long exosures to bring out the faint details and short to preserve the stars. During postprocessing the images are combined using masking techniques. The result is the best from both exposures; faint detail and good coloured stars.

[Darien]

3 minutes ago, wimvb said:

With a Dslr it is very likely that 10 minute exposures will overexpose (bloat) stars. That's why you would do long exosures to bring out the faint details and short to preserve the stars. During postprocessing the images are combined using masking techniques. The result is the best from both exposures; faint detail and good coloured stars.

 Ok so I'm currently having my eyes focused on the Fireworks galaxy? I live  about 45 min from Houston but I live in a wooded area so it HELPS ALOT. but what are some suggestions?  for the galaxy and then  preserving the stars?

 

[wimvb]

I would suggest you take the longest exposures that your setup and sky conditions allow. If you want to go for exposures of more than approximately 2 minutes, you will need guiding.

Make sure you know how your camera is aligned with the RA and DEC axes of your mount.

Examine or process your images and if you find out that stars or bright areas of your target  are overexposed, redo with shorter exposure time.

If you revisit a target it helps if you can have the camera's orientation the same.

As with everything else in astrophotography: experiment.

Good luck.

(Sorry if this is cryptic, I write this on my mobile device)

[Darien]

I do use guiding and recently just got it fix because of bad DEC backslah. but if I can get 6hrs in of 4min to 5min subs it would be great. But what duration should I do  to prevent bloating of stars and more detail?

[wimvb]

There is no one right answer, so that's where the experimenting comes in. Start with a few test exposures at half the main exposure. If still overexposed then half that, etc. Just make sure that bright stars retain colour. As soon as a star gers overexposed it will start to loose colour and get fatter.

Stars may get overexposed, but in my opinion it is very unlikely you will overexpose the galaxy. If it looks overexposed in the final processed image, that is most likely because of too much stretching.

Remember we are talking about overexposing the raw frames, directly from the camera, not the processed image.

Btw, don't forget to show your result in this forum, we love sharing in your joy when you succeed. And we need something to look at during these bright and all too cloudy summer nights.

 

And as the saying goes: if it ain't broke, don't try to fix it. If you don't see overexposure, there's no need to vary exposure time.

[Darien]

YES SIR!

[cjdawson]

Just one more point about posting up your images.  yes it's great that we all get to look at them and enjoy them.  There's also another point that there will be people on here who can make suggestions about alternative things to try when processing or capturing.  Most of the time you'll get information that will help you to produce a better picture next time out.

[Darien]

6 hours ago, cjdawson said:

Just one more point about posting up your images.  yes it's great that we all get to look at them and enjoy them.  There's also another point that there will be people on here who can make suggestions about alternative things to try when processing or capturing.  Most of the time you'll get information that will help you to produce a better picture next time out.

That's what I want to here! I want my pictures to be the best it can be!

[D4N]

I found that by using a UHC-S filter with my DSLR I didn't have to worry too much about blowing out stars, in addition to reducing sky glow it also dims the stars quite a lot without effecting the nebulosity.