Darks and Other Imaging Questions

[kljucd1]

Hi,

I use a Pentax *ist DS and an 8" newtonian on a HEQ5. I would also like to be able to capture some images that are much brighter than they currently are, see the following thread for my best so far:

http://www.iceinspace.com.au/forum/showthread.php?t=28221 (go to post 16) &
http://www.iceinspace.com.au/forum/showthread.php?t=28475

On the issue of noise, I know how to make darks but at what point are they inserted during processing?

In terms of brightening up my images, in the first link I am close to blowing the stars that make up the trapezium already. If I take longer exposures, which I am supposing is the way to brighten the image) then I will definitely blow these stars.

What am I missing here?

Any advice is very much appreciated.

Regards

Daniel...

[Zuts]

Hi,

M42 is a difficult object because of the range. Most people take different length shots to bring out the different details.

Say 15 to 30 sec for the core. Then 2 minutes for the inner nebulosity then 3 to 5 minutes for the outer nebulosity. They then combine these images using HDR techniques and get a full dynamic range without the blown out core.

As a starter just wack the images into DSS and use the HDR option and see what you get :)

As far as darks are concerned DSS allows you to select the darks you want processed at the beginning. It then creates a master dark and applies this.

There are probably far better ways of doing this but for a beginner like me I usually let DSS handle all the details.

The attached image of M42 is stacked in DSS. I forget know but i think it was 2 by 30 sec, 2 by 1 minute and 2 by 5 minutes. One 30 sec dark, 2 1 minute darks and 2 5 minute darks all thrown into DSS. Stacked using HDR option, saved without adjustments, then processed in CS2. I dont pretend it is a great image but more of example of what can be done in DSS.

[kljucd1]

Hi,

Thanks for that Zuts, much appreciated :)

But tell me, what is DSS? I have read the articles relating to astrophotograhy and didn't see it listed there.

Daniel...

[skwinty]

Hi Daniel
DSS is deep sky stacker and can be downloaded from http://deepskystacker.free.fr. It is used for registering and stacking sub exposures
Regards
Steve

[kljucd1]

Hi,

Cool, thanks I will give it a go.

Daniel...

[rogerg]

Just in case you don't end up using DSS I'd like to clarify for you...

You need to subtract reduction frames from the raw images that come down from the camera, before any processing is done on them. That's before cropping, rotating, aligning, brightness/contrast, anything!

By "reduction frames" I mean: Dark, Bias and Flat. Dark being the most critical but Bias and Flat also help when you get to the stage of being able to incorporate them in your process.

:thumbsup:

[kljucd1]

Hi,

As soon as this cloud goes away...it's all nice sunny during then the day the clouds roll in, in no time.

I bought a reticle to polar align properly and haven't even been able to do that yet!!

Thanks for the extra info, when ever I am able to, I will give it a go.

Daniel...

[Kirkus]

Hi Daniel,

Looking at your early shots of M42 just thrilled me to pieces. I've taken several shots at it myself and my attempts are no where near as nice as yours. Anyway, I'm really looking forward to watch your progress.

Good luck!