Taking on the Horsehead and Flame - Tips Please

[richyrich_one]

Hi All

It's looking like a possible allnighter tonight and I want to tackle the Horsehead and Flame.

Any suggestions? Alnitak is my major concern.

Suggestions much appreciated.

 

[newbie alert]

Id say keep your iso low,i shoot at 800 with a long ish exposure..are your skies dark? whats your equipment,scope and canera..just a camera and lense?

[ollypenrice]

Alnitak will do what it does. Not much you can do about it at the capture stage. Your main concern needs to be going deep enough on the HH. 

It's in the processing that you can blend very gentle stretches of Alnitak with hard stretches bringing out the HH.

Olly

[richyrich_one]

2 hours ago, newbie alert said:

Id say keep your iso low,i shoot at 800 with a long ish exposure..are your skies dark? whats your equipment,scope and canera..just a camera and lense?

Thanks newbie.

Equipment as in my sig. I usually shoot at ISO 800  300-600 secs. Skies are reasonably free from LP.

 

[richyrich_one]

2 hours ago, ollypenrice said:

Alnitak will do what it does. Not much you can do about it at the capture stage. Your main concern needs to be going deep enough on the HH. 

It's in the processing that you can blend very gentle stretches of Alnitak with hard stretches bringing out the HH.

Olly

Thanks Olly.

I always wonder whether to go for some shorter subs or not.

Good to know it's really all in the processing.

Look out for a "Processing Horsehead and Flame - Tips Please" thread in the next couple of days.

[cjdawson]

Nothing stopping you taking some subs of the horse head with alnitac out of the FoV.   That will help you go longer

[ollypenrice]

I can look at linear data as soon as it comes in by opening it in a separate programme on the PC. If you can do this with your rig it's very useful because you can see to what extent the linear data is saturated (burned out) in full length subs.

If, unstretched, Alnitak is already a large white blob then you would benefit from a few short subs. If it looks like a split double star then your raw data has it covered and crafty processing can blend different stretches. The image on the left, below, shows a ten minute sub unstretched using a deep-welled CCD and F7 apo refractor. It is clearly perfectly healthy and can, therefore be stretched to give the full dynamic range needed for both the star and the nebula. (Be aware that this particular scope-camera combination is particularly good on Alnitak. You may not be quite so lucky. Our other rigs don't handle it anything like as well as this.

If you find that you do need some short subs you won't need many because, by definition, you're only after the bright star so your signal to noise will be very high anyway. You won't, therefore, need to do a deep stack of subs to control the noise.

Have fun. It's a wonderful target.

Olly

 

 

[ollypenrice]

Just now, cjdawson said:

Nothing stopping you taking some subs of the horse head with alnitac out of the FoV.   That will help you go longer

Maybe, maybe not. Alnitak and other bright stars sometimes produce enormous 'lighthouse beam' flares when out of shot while not doing so when the star is in the frame. I've seen this quite often. We did a wide NAN mosaic in the summer. The frame with Deneb in it was fine but Deneb produced flares in several outlying frames. Worth a try though.

Olly

[richyrich_one]

21 minutes ago, ollypenrice said:

I can look at linear data as soon as it comes in by opening it in a separate programme on the PC. If you can do this with your rig it's very useful because you can see to what extent the linear data is saturated (burned out) in full length subs.

If, unstretched, Alnitak is already a large white blob then you would benefit from a few short subs. If it looks like a split double star then your raw data has it covered and crafty processing can blend different stretches. The image on the left, below, shows a ten minute sub unstretched using a deep-welled CCD and F7 apo refractor. It is clearly perfectly healthy and can, therefore be stretched to give the full dynamic range needed for both the star and the nebula. (Be aware that this particular scope-camera combination is particularly good on Alnitak. You may not be quite so lucky. Our other rigs don't handle it anything like as well as this.

If you find that you do need some short subs you won't need many because, by definition, you're only after the bright star so your signal to noise will be very high anyway. You won't, therefore, need to do a deep stack of subs to control the noise.

Have fun. It's a wonderful target.

Olly

 

 

Thanks again, that's really good advice.

Hopefully it will all come together and I can do it justice.

[richyrich_one]

33 minutes ago, cjdawson said:

Nothing stopping you taking some subs of the horse head with alnitac out of the FoV.   That will help you go longer

I'm shooting with 130 tonight so with that FOV I'm not happy with the framing.

It would work with the 250 though. That's for another night.