Problem saving snapshot with ASI294PRO

robrj
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Re: Problem saving snapshot with ASI294PRO

Post by robrj » Thu Mar 01, 2018 2:35 pm

I just noticed you're saving with the snapshot. I've not tried that yet. I always use Save As Viewed in the pulldown. I'll try it myself the next time I'm out.

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admin
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Re: Problem saving snapshot with ASI294PRO

Post by admin » Thu Mar 01, 2018 6:41 pm

Hi,

just to report that I checked with Sam @ZWO and he says that the RAW format for the 294 matches the normal RAW format for other models. Apparently the odd bayer layout is hidden by the chip firmware (Sony) and there is no way to get the image in the original pixel pattern. ZWO also do not currently use the HDR option of this sensor.

My instinct says that in order to put out a standard RGGB bayer pattern from a sensor with that weird 2x2 block layout, the chip itself must be doing some fancy footwork moving pixel values around (probably swapping selected adjacent ones). This would tend to lead to a slight loss of effective resolution in the final image.

@robrj - good to hear that yours is working fine - what colour space do you use? presumably a RAW one?

cheers,

Robin

LaCasaCorp
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Re: Problem saving snapshot with ASI294PRO

Post by LaCasaCorp » Thu Mar 01, 2018 7:54 pm

Yah, I remember having read something about the reshuffling of the pixels done internally (and apparently doesn't lead to a resolution loss).

I used just snapshot because I was testing some geometrical misalignment in my scope and I needed simple, singe frames, maybe is that command that saves the file in a different way... When I use live stack everything is saved correctly.

robrj
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Re: Problem saving snapshot with ASI294PRO

Post by robrj » Thu Mar 01, 2018 8:04 pm

admin wrote:
Thu Mar 01, 2018 6:41 pm
@robrj - good to hear that yours is working fine - what colour space do you use? presumably a RAW one?
I use RAW16. I never tried the snapshot button though. I always do mine with "Save as Viewed" which seems to work (and which the OP said worked fine with his). I'll test it next time I'm out.

What's the primary difference between "Save as Viewed" and the Snapshot?

Another interesting thing to note, when I save a fits file and open it with Fitswork, it's already debayered. I seem to remember, with my other ZWO cameras (ASI185MC & ASI224MC), I've had to debayer any fits file with Fitswork.

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Re: Problem saving snapshot with ASI294PRO

Post by admin » Thu Mar 01, 2018 8:43 pm

'Save as Viewed' saves the current state of the live stack as you are seeing it on screen (but at 16 bit depth). It is already converted to RGB because that's required to align each frame to the stack (you can't shift a raw frame 1 pixel sideways or rotate it a bit and expect it to stack properly!)

'Snapshot' saves a single frame from the camera without processing of any sort. Usually it's the next frame to finish, except if you have reasonably long exposures selected and haven't altered the controls since the last frame finished. In that case it will snapshot the frame you are looking at on screen (the last one to finish).

So, snapshots will be RAW but live stack saves are RGB.

cheers,

Robin

bazza104
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Re: Problem saving snapshot with ASI294PRO

Post by bazza104 » Sat Jun 08, 2019 2:10 am

Not sure if this is the same but after sensor ZWO294MC Pro analysis and using suggested setting of 170 21.7 sec lights set at Raw16. and taking 40 darks and flats immediately after.
To my suprise the stacked image was already deyaered but as RGB24 and the Dark and flats also set to Raw16 would calibrate until I set the camera to RGB24 and took new lights and darks????

Barry

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