First prime focus attempt at DSO

[Zendrix]

Hello all!

I passed from theory to action in astroimaging. After my ring nebula unsucessfull attempt due to the fact that i was using a 25x eyepiece when what i really wanted was prime focus, i finally gave it a go to prime focus. I aimed at the laguna nebulae, m8. I have a lot of light pollution and no filter.

My setup is what i can afford for now, so i'm trying the best out of it: skywatcher 130mm, F=900mm, EQ2 (polar aligning is a challenge), 4x r.a. motor, Canon 1000d at prime focus.

I stacked in DSS, 2 different stackings:

1st, 53x20s subs, 25 darks, 20 bias... the final TIFF file was something like i normally see, very bright. I played around with it in photoshop and i could only come up with this

2nd stacking: I added 10 flats to it (if i understood correctly, i can take flats with a t-shirt stretched over the cap of the scope, point to a clean morning sky and ISO100 and A/V mode on camera). The final stacking result was a darker TIFF than the first, the black of the sky wasn't to far from a normal picture. ( i suppose because in the 1st stacking, the RAW settings had brightness up to 10, although it gave me something closer to what i normally see as a final TIFF result: very bright picture).

So, am i not getting that much detail from the nebulae because 18 minutes total isnt that much? is it light pollution the main problem? is it the processing? ( i used some gradient terminator in photoshop, i played with levels and curves, etc...)

So i just would like your input please, once it is my first baby steps into it and im really excited...

[Zendrix]

3rd attempt: http://stargazerslounge.com/gallery/image/13464-laguna3/

[kenmyers]

Looking good! congrats.

[Zendrix]

thanks ken!

Any tips, advises, critics?

Cheers,

Rui

[sologuitarist61]

Very nice image, well done

[rfdesigner]

Looking good, you're going in the right direction.

Just out of interest, why are you using bias frames? (I'm not convinced you need them yet, I could be wrong)

And yes more imaging time is always better.

Derek

[Zendrix]

Thank you guys! that's encouraging!

Just out of interest, why are you using bias frames? (I'm not convinced you need them yet, I could be wrong)

I use it because i read other people using them.. i don't know what good they do to me... I also have some doubts about flats, because after processing with flats i got a darker image, not so "processable" TIFF (although first processing had RAW brightness settings at 10 in the first stacking... it gave me a better image to work with, anyway... maybe my flats were not properly taken.. i took them after leaving the camera in same position from yesterday, same focus, ISO 100 and a t-shirt at the end of the scope, pointing blue sky... but there was a little stain in the center, don't know what was it from)

I will try to mode my canon myself as well... i suppose it changes drastically the amount of info in nebula.

I really appreciate your input!

Take care,

Rui

[kenmyers]

You are FAR ahead of me I am afraid. My advice would be useless

Great looking capture, I like space to be dark so I prefer the second image to the first but you did capture a lot more 'dust' or 'glow' in the first image... so I am uncertain which is better.

Both better than anything I have done. I would be chuffed if I was you.

[Zendrix]

Thanks Ken! I am!

I hope i can mod my camera in the future and use my scope under clean skies... too much light pollution in the city!

I think i prefer the 3rd attempt though, which i posted in the link after. Processing is very relative, i guess.

I wish the best to your imaging... i'm sure you are better than you are saying!

Cheers,

Rui

[rfdesigner]

Thank you guys! that's encouraging!

I use it because i read other people using them.. i don't know what good they do to me... I also have some doubts about flats, because after processing with flats i got a darker image, not so "processable" TIFF (although first processing had RAW brightness settings at 10 in the first stacking... it gave me a better image to work with, anyway... maybe my flats were not properly taken.. i took them after leaving the camera in same position from yesterday, same focus, ISO 100 and a t-shirt at the end of the scope, pointing blue sky... but there was a little stain in the center, don't know what was it from)

I will try to mode my canon myself as well... i suppose it changes drastically the amount of info in nebula.

I really appreciate your input!

Take care,

Rui

I thought that might be the case.

Many people get quite muddled over bias/flat/darks.

In my opinion flats are the most important.

What you are trying to do is to make every pixel respond in exactly the same way. You are calibrating the zero point and the 'gain'.

By removing a dark frame you get each pixel back to it's zero point. Which will make things look darker.. this is good, you can brighten things up later in post processing, but you'll see more information.

By dividing by the flat you correct each pixels gain. The flat field has an offset, a bias level, implicit in it, so we take a shot of the same length as the flat, and remove that to leave us with the correct 'gain' reference.

If you don't bother with darks, you get a few hot pixels and things look a little noisier than they might otherwise need to be.

If you don't bother with flats you just can't zero in on the sky background when you're processing, this is why I concider flats more important.

Getting good flats is hard.. I've seen people here like Ollypenrice.. one of the best imagers here, who say they can't get certain flat field techniques to work. Don't be put off from trying but remember even the best have trouble.

clear skys

Derek

[tingting44]

looking fab mate!!! you have all the same equipment as me!!! i have the SW130p and cannon 1000d, but i think my AZGOTO mount is going to let me down as i have been told i am not going to be able to image any nebula with this mount loving your 1st attempts tho mate!!! what program did u stack with?

[Zendrix]

Thanks Derek! I'll certainly have that in mind! Flats are troubling me because i suppose you have to have the same orientation relationship camera/telescope from the lights session and the flats themselves, no? so that means either u take them in late afternoon or you wait until late morning of the same day of shooting (because those are the limit times for a blue evened sky, no?) in order to keep the same focus and orientation. I have heard of some other ways with white backgrounds, but im not sure how they work...

Thank you tingting, we are equipment buddies! haha I stacked all this info in Deep Sky Stacker (DSS), its a free program you can easily download nad its amazingly good, at least for me who doesnt know any better so far

Moving further up for the Orion one!

[Zendrix]

the 3rd attempt with some noise reduciton http://stargazerslou...-laguna-nebula/

I've gotta start controling those stars now, they were going way too thick in this attempt...

[rfdesigner]

Thanks Derek! I'll certainly have that in mind! Flats are troubling me because i suppose you have to have the same orientation relationship camera/telescope from the lights session and the flats themselves, no?

Yes, this is essential.

so that means either u take them in late afternoon or you wait until late morning of the same day of shooting (because those are the limit times for a blue evened sky, no?) in order to keep the same focus and orientation. I have heard of some other ways with white backgrounds, but im not sure how they work...

They work in much the same way, perfectly even illumination of the optics so you can see how the sensitvity changes. So long and the scope is bathed in nice even light it doesn't matter how far it's travelled to get to the camera, it will do for a flat.

Derek

[tingting44]

i have only bothered with lights and darks, that might be why i dont get that great results when stacking