Sadr region in HaII 3nm

[ian_bird]

Hi

Working my way up to longer and longer (for me) exposures with the new (to me) 3nm HaII filter.

This is a single 1200 second sub from last night - all I had time for before the clouds ended play. Saves on stacking I suppose. ;-)

Cheers

Ian

[ian_bird]

 I spent a good 30 minutes messing around with focusing. FocusMax had the night off - so no joy. I went with my focus position from last time. 

Then I worked up with 300s, 600s, 900s and 1200s. I was going for 1800 seconds and was up around the 1200s mark when the clouds called time. 

Next time I will do 300s, 1200s and then try 1800s again.

[ollypenrice]

Good to see the RC in action, Ian. The little bright patch next to Sadr is going to want watching during the stretches. It's saturated to flat here but one way or another you should be able to get some nice modelling in it. Whatever is not saturated in the linear (or the shorter linear) data can be coaxed into the final image with care.

Collimation looks good.

Olly

[ian_bird]

Thanks Olly

I was really hoping you would comment on this. The plunge into HaII 3nm is a bit daunting. A lonely road to tread. Well - for me it is. I'm pushing my mount to the limits with these kind of sub lengths.

I will try to improve upon the processing - I know Sadr and it's environs got away from me. But on a single sub I was just looking to see what kind of detail I had.

Really appreciate your comments. I have been having a bit of a mare recently with my Astro - so a friendly (and learned) voice is a big boost!

Love to Monique.

Cheers

Ian

PS - Thanks for the PS action that does the Ha stretch. Very kind of you to give me that one!

[ollypenrice]

21 hours ago, ian_bird said:

Thanks Olly

I was really hoping you would comment on this. The plunge into HaII 3nm is a bit daunting. A lonely road to tread. Well - for me it is. I'm pushing my mount to the limits with these kind of sub lengths.

I will try to improve upon the processing - I know Sadr and it's environs got away from me. But on a single sub I was just looking to see what kind of detail I had.

Really appreciate your comments. I have been having a bit of a mare recently with my Astro - so a friendly (and learned) voice is a big boost!

Love to Monique.

Cheers

Ian

PS - Thanks for the PS action that does the Ha stretch. Very kind of you to give me that one!

What you could do to get the very bright stuff to show structure would be a simple grey point stretch from linear. Use levels and move the mid point left. Look only at that little bright bit near Sadr. Stop stretching when you have it bright but not saturated and layer it in in Ps. Maybe use only the shorter subs.

Olly

[ian_bird]

Olly

Thanks. Will give it a try. I forgot I had some shorter subs! A bit fixated on getting longer ones I suppose.

On the plus side - I got a 1800 second sub tonight. Sadly - despite the guide graph (2 second guide exposures) looking like a flat line - the stars are all elongated in one direction. I didn't get that in the 1200 second sub.

I'm thinking it's OAG time. I'm at 1333mm focal length using a guide scope (welded to the top rail).

At the moment - I am working on image acquisition. Image processing will have to wait. Olly Penrice or Sara Wagner I am not when it comes to long exposures!

But having fun.

Thanks for your comments Olly. Always nice to know you are covering my back!

Love to Monique as always.

Cheers

Ian

 

[swag72]

This is looking really nice so far...... Having done 30m subs at f3.9 the nebulosity above Sadr wasn't blown out at all, so I reckon that you'll be fine. Just watch the curves and stretching and blend layers together if needed - One for that bright area and one for the rest. The 3nm Ha is a great filter for sure

[ian_bird]

Thanks Sara.

I'm having trouble with my tracking at 30m, but not at 20m. Which is a bit odd.

Is it worth pushing on out to 30m - or is 20m almost as good.

Cheers

Ian

[swag72]

I can't see why 20m is OK and 30m isn't...... Regarding guiding they are much a muchness.... But you could be seeing other factors creeping in the longer you go..... Such as flexure or polar alignment.

[ian_bird]

Yes - it's most odd. I have a PoleMaster so the PA is pretty good. And following Olly's advice my guide scope (a WO 72mm Megrez) is welded to the top rail - with proper tube rings - not guide scope rings. And it's an RCT - so no mirror flop. 1333mm focal length.

The guide graph was as flat as a pancake last night when I tried a 30m sub. But the sub is unusable.

Maybe an OAG is in my near future! I have one - I just don't like to use it. ;-)

This is a centre crop of the failed 30m sub. "Scratches head". Oh well - if it was easy...

I will try again tonight.

Thanks again Sara for the feedback. Much appreciated.

[ian_bird]

It seems that last nights abortive attempt to get a 30m sub was a glitch. I've just pulled down my first 30m sub tonight - and whilst not brilliant - it's usable.

Happy days indeed. ;-)

Cheers

Ian

PS - Or maybe tonight is a glitch - and last night was the norm?

PPS - Nah! Think positive Ian! ;-)