Struggling with the histogram

[bluesilver]

Hi, I am using SharpCap Pro, I have been using it more many years for plate solving, but want to start to use it more for imaging now as i am finding more and more things I like about it.

I am using a asi2600mc ( colour camera )
I have opened up the histogram, clicked on the brain icon and got my sky darkness figures back
Now from memory they were suggesting an exposure time of around 78 seconds for gain 100 and about 470 seconds for gain 0
Also had the figure for black offset, I think this was about 26

So i decided to give the gain 100 figures a go, I just clicked on the apply icon and SharpCap automatically changed all the camera setting to what the read out said, so all good there.

Now at this stage i just realized i have never actually used SharpCap to image with, So i just went up to the start capture tab and entered the 78 seconds and just a single frame to see how things go and clicked Start, I see the seconds counting down in the bottom window.
After it finished, the histogram showed nothing, everything looked as if it were up against the left-hand side, there was absolutely nothing in the histogram.
I think the reason there was, I had a small red box, I think this is one of my issues, I don't think that was supposed to be there, I just read something about click FX to turn it off or on.
I did get a image up of what i was imaging ( Thors Helmet )

Also tried the gain 0 settings, same result.

I have just loaded up the single images that i had taken and now have a histogram, but there is no separation on the left hand side of the histogram, I figured those figures from the brain function would give me a good histogram.

These are just a single image, no flats, darks, etc.
Is there something i am missing here, as i thought that there is suppose to be a small gap on the left hand side of the histogram?

Any help is appreciated.
Cheers.
Below is the two single images that i have taken,

78 second image gain 100

Thors Helmet 70 second.jpg (216.6 KiB) Viewed 1079 times

470 second image gain 0

Thors Helmet 400 second.jpg (207.58 KiB) Viewed 1079 times

[admin]

Hi,

so, first, I can see from your screenshots that you are using a very old version of SharpCap 4.0 - nearly 2 years old now. There have been lots of bug fixes and improvements in updates to SharpCap 4.0 since then. I would strongly advise downloading and installing the latest update from https://www.sharpcap.co.uk/sharpcap/downloads

On the subject of the histogram, I think the red box you are referring to is the selection area box. When this is active, SharpCap only measures the histogram for the pixels inside the box, so if it was active and the box was small then there will not be much data in the histogram. The box can be turned on and off using the appropriate toolbar button (see https://docs.sharpcap.co.uk/4.0/#The%20Tool%20Bar - the button is numbers 13 and has a picture of the red selection box on it). Turning the selection area off will give you the histogram for the whole image.

On the screenshots from the loaded images, these look fine to me - there is some separation between the left hand side of the histogram peak and the left axis (when you use the smart histogram, it doesn't aim to put a big separation in, rather to put in 'just enough').

Finally, from the point of capturing images, the two basic ways when deep sky imaging are

1) Use the 'Snapshot' button to capture a single image
2) Use the 'Start capture' button and either specify a number of frames to capture - say 30, or a time to capture for - say 60 minutes.

cheers,

Robin

[bluesilver]

Appreciate the reply, yes, i did have the latest version installed, I was doing a bit of trouble shooting with another issue i had and forgot to go back to the latest version.
It is good to know the histogram is ok, I will keep on using the recommended values each time i get out to image as it dose a great job.
I will take a look at turning off that red box, I think it must have a bit of a memory as last time i was doing a sensor analysis and seams to have started back up with this memory.
Cheers.