Histogram display

[ColinR]

Hi,
As a newbie I'm not sure if the attached picture of last night's histogram is OK. The details are as follows:

Altair Astro 183C Pro TEC
-20C
RAW12
180s minutes exposure
Gain 389
Black Level 47
Astronomik CLS CCD
Clouds coming in - Hence no image

As can be seen there is clear separation of Red from Green/Blue and an unusual pattern along the bottom of the graph.
I have seen similar in my search for an explanation but not found any supporting text to explain.

Thanks in advance for any help on this.
Colin

[BlackWikkett]

Hi ColinR,

Are you using the native Altair driver, when you started the camera in SharpCap (SC) did you select it by name or did you use the ASCOM driver? Not sure about Altair but the ZWO version of this camera has Red and Blue calibration sliders I don't see in your image. these allow you to adjust white balance. Your histogram looks normal for using a CLS filter.

If you're capturing raw images for later processing I wouldn't worry too much about white balance this can bee done in post processing. On the other hand if you are live stacking and looking for instant gratification white balance is something you'll defiantly want.

Hope this Helps, Wikkett

[ColinR]

Hi BlackWikkett,

Thanks for your reply. If I have understood it correctly then I am reassured that the histogram is perfectly normal for this image.

In answer to your questions:
I am using the native Altair Astro driver having selected this specific camera from the SC camera menu.
I am taking RAW images to be later process in PixInsight.
I will therefore not be live stacking.

So thanks again for your help and reassurance that the histogram is normal for this set up. (I'm assuming that the CLS CCD filter is the source of the erratic bottom lines?)

As I am finding out the hard way, there is much more to using SharpCap and an astro camera over my modded DSLR comfort zone. But I'm certain that the transition will be well worth it.
Thanks again.

ColinR

[turfpit]

Colin

I would say the filter affects the colour balance - easiest way is to take a frame with and without filter and satisfy yourself. As you stated, colour balance for RAW can be sorted in post-processing.

This is a typical (for me) log histogram of a RAW capture of a DSO using an Altair 183C. I always undock the histogram as a personal preference.

Don't forget the lessons learned with the DSLR, they will stand you in good stead.

Dave

SC-183C-histogram.JPG (58.57 KiB) Viewed 2601 times

[ColinR]

Hi Dave,

Sorry to trouble you again, but what does "undock the histogram" mean?

Colin

[turfpit]

Colin
Grab the histogram title bar with the mouse and drag it to one side. It will undock and become smaller. The histogram can be moved around to a convenient location and the capture screen is maximised. The histogram can be moved back over the docking point to resume the initial size.

There will be ‘proper’ terminology for all of this and no doubt the Windows propeller heads will
emerge soon to correct me. I wish them luck with that ... LOL

Closing the histogram and restarting will revert back to what you see now.

At this point in your experience, a skim read of the manual would be useful.

Dave

[note: All the camera controls can be re-ordered or minimised to suit personal preferences.]

[ColinR]

Dave,

Thanks again for your input. Yes I am currently working my way through the manual. A lot to take in but I'll get there!

Thanks

Colin