Save RAW Image

[MAT_Blue]

All of the images (FITS format) that I capture have the White Balance settings from the "Image Control" section applied to them. I have a ZWO ASI294MC-Pro camera. How do I get Sharpcap to NOT apply any white balance (or any other adjustments) to the RAW image data and just save the RAW data in the capture file? I spent the last hour or so trying to figure out how to do this but was not successful.

[Menno555]

Hi and welcome

White balance is something that can't be disabled, it's part of the camera. You can however set is to the default of the camera. For your camera that is Red 52 and Blue 95.
Having said that: the white balance is something that is almost always altered during processing. When I had my 294 camera (and now also with my ASI071MC Pro), I set the white balance to Red 50 and Blue 50. This is giving a green-ish result but with processing that is altered.

Menno

[admin]

Hi,

As Menno says, adjusting the white balance alters the data that comes from the caemra to SharpCap, so you cannot save without the effect of any adjustments made with those settings. I don't quite agree on the defaults for ZWO cameras

The 52/95 setting seems to be the one ZWO likes to set as default, and it gives a reasonably natural look to an image, but 50/50 is the setting that does not adjust the pixel values at all, so my advice is to always use 50/50 for capture and, as Menno says, fix any colour cast in post processing.

cheers,

Robin

[Chuckwagon]

Can the White Balance be calibrated with a Grey card in a similar way to how it is done for a custom balance on a modded DSLR?

[Menno555]

You could use a grey card I suppose but for astrophotography it's kind of useless. Due to light pollution, gradients, and so on, the "correct" white balance will always differ. For moon captures, a grey card will work though since the moon reflects sunlight.
Also, when you capture and save in RAW format (which FITS is), the white balance is not that important since you can adjust that easily in processing.

But the easiest way to get a "correct" white balance if you want that, is to use the Histogram with the Logarithmic box checked.
Go to the object(s) you want to capture, set your desired exposure time, gain and brightness/offset and then adjust the Red and Blue slider until the RGB lines are divided equally or use the RGB Mean values of the Histogram until those are roughly the same.
This has to be done for every session you do and can also change during a session when your target gets lower or higher in the sky.
That is the reason why with astrophotography it's easier to use a fixed white balance and alter it during processing.

Menno

[MAT_Blue]

That doesn't seem right. You're saying that what I set in SharpCap gets sent to the camera and it changes the pixel date before it sends it to SharpCap? None of the other programs I use for capturing does that, as far as I can tell. Or, if they do, they somehow undo it before saving the image. I don't have to play around with white balance settings in other programs. I did find that setting brightness to 1 and Red and Blue to 50 generates the same thing as other capture programs. The 52/95 "default" values are laughably bad.

[calan]

The 52/95 "default" values are laughably bad.

So is the hardware color balance of the ZWO cameras. They should be called green cameras, not color cameras.

Not to mention that they call that setting "Brightness". It's actually the offset.

[MAT_Blue]

The 52/95 "default" values are laughably bad.

So is the hardware color balance of the ZWO cameras. They should be called green cameras, not color cameras.

Not to mention that they call that setting "Brightness". It's actually the offset.

That's fine. It's a symptom of the Bayer Matrix. It's easy to fix in post-processing. Wonking it up in some ill-defined way is not. Then all of your darks and flats have to have the same exact wonking or they're worthless.