Albireo, an object lesson

[DaveS]

In why you shouldn't use 300 sec subs when imaging bright doubles  

In my defense, I have been used to trying to capture faint tidal structures around already faint galaxies, or even fainter NB structures, so tend to thin in hours, and regard a 300 sec sub as being short. I was just looking for something to image in in this horrid twilight, and thought Albireo might mage a good target.

So captured 12 x subs in short G2v, 300 sec each R, G, and 525 sec in B. The subs showed huge halos as they came in, even with Chroma filters. Ah well should be clear tonight so will give more sensible exposures, 10 sec has been suggested to me.

[Sunshine]

It's a wonderful image of one of the skies crown jewel doubles!  you've really captured it as I see it.

Edited July 4, 2022 by Sunshine

[Saganite]

54 minutes ago, Sunshine said:

It's a wonderful image of one of the skies crown jewel doubles!  you've really captured it as I see it.

I have to agree, it is a lovely image...

Edited July 4, 2022 by Saganite

[DaveS]

Thank you both.

So perhaps not quite as bad as I thought?

I think I will have another look tonight and experiment with different exposurs to give bright stars without saturation.

[carastro]

Looks fine to me Dave.  Why don’t you do half the subs 150secs and half 300secs and compare the results for a definitive answer  
 

Carole 

Edited July 4, 2022 by carastro

[DaveS]

Thanks Carole.

There may be a clear night tonight, if so I will try a few single subs to see how the histogram looks. probably start at 15 sec and double it until I get saturation, then dial it back a bit.

[Swoop1]

There is nothing wrong with that image @DaveS- at east to my uneducated eye.

I like the way the intended targets stand out against a well populated background of stars.

[Ian McCallum]

Just wow!😲

[Mr Spock]

Looks good to me. I can see a little elongation in the stars though - tracking?

[Ags]

Albireo looks well controlled with good color despite the long subs. Excellent image!

[DaveS]

1 hour ago, Mr Spock said:

Looks good to me. I can see a little elongation in the stars though - tracking?

Possibly. I noticed a little elongation too. I may try another stack with more stringent limits for elongation, see how many subs are rejected.

There shouldn't be any cable drag as all the power and data cables are routed through the axes, this is the most likely cause of trailing with ASA mounts.

The PA is a bit further out than I'm really happy with, but I want to wait until I can start earlier in the night, as trying to deal with technical issues when I want to turn in isn't conducive to good outcomes.

[ollypenrice]

Shorter subs would give the cores more colour saturation because the brighter they get, the whiter they get. I'd experiment with some very short ones - 10 to 15 seconds, to see what they give, but the present image is nice. When the stars are bigger their outer parts get nearer to each other and that makes the colour difference show well. It's like observing Albireo slightly out of focus, which many people do to enhance the colour contrast.

The background's a bit dark for my taste, though. Purely personal.

Olly

[DaveS]

My plan is to start with 15 sec subs, then keep doubling until the histogram shows saturation, then dial the exposure back until I have bright stars (So the background stars show up) .