3 targets with small data

[alpal]

This was the first time I had imaged these targets &
the seeing was poor so I just had a go at many instead of concentrating on one.
All taken with an 8" f/6 Newt. & QHY9 mono camera.

The Rosette Nebula.
I took 81 minutes of the Rosette Nebula.
4 x 3 minutes each of RGB binned 2x2.
5 x 3 minutes of L binned 1x1
3 x 10 minutes of Ha binned 1x1.

There were so many bright stars that 10 had bleed lines that had to be removed.
Maybe I would need to do hundreds of short 60 seconds frames to re-do this target?

The Running Man.
42 minutes of data.
3 x 3 minutes each of RGB binned 2x2.
5 x 3 minutes of L binned 1x1.

Once again - 14 bleed lines had to be removed with the spot healing brush.


NGC 3132 Planetary Nebula.
1 x 3 minute each of RGB binned 1x1.
For some reason they didn't align properly in Deep Sky Stacker.
It's so small that I'd need a Barlow & top seeing to image this target.


Any advice appreciated.

cheers
Allan

[John K]

Nice images Allan,

A bit on the noisy side but look great!

John K.

[alpal]

Thanks John.
yes - very noisy data.
As I said - maybe hundreds of 1 minute sub frames would pull the signal out
without exceeding the well depth of the bright stars?
I have never tried that before with my mono camera.
Actually some light clouds came over & I lost many sub frames -
and some clown let of huge fireworks at 1am right in the direction of where I was shooting.

cheers
Allan

[RickS]

What do the "bleed lines" look like, Allan? The KAF-8300 doesn't normally bloom (except for small horizontal blooms from bright stars when binned and at full gain.) I have used a SX H-18 and QSI683 with the same sensor and relatively long exposures are fine.

Cheers,
Rick.

[alpal]

Hi Rick - I always get this problem when the well depth is exceeded on bright stars.
I knew it was happening so I at least kept the sub frames to only 3 minutes.
This is the stack of luminance specially processed with HDR toning to
exaggerate the effect - on the Running Man.
The targets I chose just had very bright stars with such faint nebulosity.
I was using gain = 5 offset =100. ( 5 = 5% - I think )

cheers
Allan

[RickS]

Allan,

I've never seen anything like that from a KAF8300 before and I have plenty of subs from SX and QSI cameras with the same sensor where the star cores are saturated. It's an anti-blooming sensor so exceeding the well depth shouldn't be a problem. I don't think your camera is operating correctly...

Cheers,
Rick.

[PRejto]

Hi Allan,

I also have never seen such a result from my Moravian G2-8300 camera. I do get horizontal blooming at 2x2 on bright stars but that looks nothing like the dark streaks you are seeing. I agree with Rick that something seems wrong with your camera. Have you tried different capture software to rule out that possibility? Is the camera driver up to date? Are you using a native driver or connecting through ASCOM? Has your camera always done this?

Nice photos for such little data!

Peter

[alpal]

Hi Rick,
When a camera shows signs of blooming you get a bright white line.

see link:
http://www.themcdonalds.net/richard/index.php?title=File:Astrophotograp hy-Blooming-Example.jpg

and here:
https://www.astronomics.com/blooming_t.aspx

I am getting dark lines.
Surely that's telling me that the pixels are being bled off?
This bleeding process somehow causes a dark line.


cheers
Allan

[alpal]

Thanks Peter,
I am not sure if it's a fault.
As far as I know it's always done that.
I don't think it's software related.
Remember my example picture has been exaggerated with HDR toning.


cheers
Allan

[RickS]

Allan,

"Normal" blooming only occurs in a vertical direction. Your artifacts appear to be in a horizontal direction. This can occur when full well is exceeded in the horizontal shift register (and Janesick, the CCD authority, calls this horizontal blooming, even though it may result in a dark line). This is the same effect that Peter mentions although it is normally seen with binning on the KAF8300 and the lines are typically shorter. I wonder whether you have the gain cranked too high? It should be set so that a full well results in an ADU value no larger than the maximum 16-bit unsigned value of 65355.

Cheers,
Rick.

[alpal]

Hi Rick,
the gain of 5 gives me full well depth at 56,000.
Maybe I should ask Theo at gamma?

cheers
Allan