Camera or Pro License Problem??

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carlwagle
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Camera or Pro License Problem??

Post by carlwagle » Wed May 08, 2019 2:50 am

I use a Celestron SKYPRODIGY 130 Computerized Telescope. Focal length of 650mm and a focal ratio of 5. It has been an inexpensive and satisfactory way for me to get introduced to astrophotography.
My camera is a ZWO ASI 178MC. I have been getting good stacked pictures, except for the hot pixel, up until the time I got my Pro License about a week ago. I sent in 2 photos on April 24th, 2019, 7:05 PM that show the hot pixel forming a curving line reproduced in at least three places on the frame. Each being one dot corresponding to a picture in the stack. Over time I noticed these lines becoming ovalish, then latter dense enough to look like a bloated star. These "artifacts" also got very, very faintly, widely reproduced as noise. However, my stars were always stacked reasonably well.
I got the Pro License about a week ago because I wanted to see if Dark Frames could be used to suppress or cover up these images of hot pixels. They are still with me! Not only that, but now I can't get stacked pictures of the stars. My stacks now look like I thumped the leg of the tripod during the stacking. Actually my experience before the Pro License in winds gusting from 5 to 20+ mph tells me that the excellently designed SharpCap Live stacking feature would have rejected a picture after a tripod leg thump! In the gusts, it rejected about 30% of them but what was saved made for a flawless stack,,, except for the hot pixels.

Here is the results of my 2nd chance to use the Pro License from last night:
1 no Good star staking. At best one may appear as two, perhaps as many as four in a row, often just a streak.
2 it will operate as stacking on empty dark space,, no stars, or just one star. it will stack WELL Vega by it self.
3 in all the above you can see with high manification that one bright hot pixel. It often looks like a very small bright box, Its reproductions look like small crosses made from five pixels, there still is a bit of this same in the background as noise.
4The same problem results even if I select the NONE in the dark frame selection line,, using no dark frame.

The above leads me to believe my StarCaps tracking is being mislead from the stars to the brighter but much smaller hot pixel..

What next can I try?

Do I have a camera issue that I should bring up with its manufacturer?

I will next send a picture of one of the typical mistrackings along with the camera settings. please ask for more info if you need it. Carl

carlwagle
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Re: Camera or Pro License Problem??

Post by carlwagle » Wed May 08, 2019 3:12 am

Attached is my picture of poor staking.
Attachments
Stack_16bits_20frames_62sVERY POOR STACKING.jpg
Stack_16bits_20frames_62sVERY POOR STACKING.jpg (130.54 KiB) Viewed 103 times

carlwagle
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Re: Camera or Pro License Problem??

Post by carlwagle » Wed May 08, 2019 3:19 am

HERE is the Camera settings. I coluld not include the first two lines of this text. This weeken I will learn how to make and send you a "Screen Shot". Carl Wagle.
PS: thanks for any advice you can give me.


[ZWO ASI178MC]
Pan=0
Tilt=0
Output Format=PNG files (*.png)
Binning=1
Capture Area=3096x2080
Colour Space=RGB24
Temperature=23.8
Hardware Binning=Off
High Speed Mode=Off
Turbo USB=40
Flip=None
Frame Rate Limit=120 fps
Gain=200
Exposure=3.101013
Timestamp Frames=Off
White Bal (B)=48
White Bal (R)=50
Brightness=50
Auto Exp Max Gain=130
Auto Exp Max Exp M S=13631
Auto Exp Target Brightness=106
Mono Bin=Off
Banding Threshold=35
Banding Suppression=0
Apply Flat=None
Subtract Dark=C:\Users\CHWag\Desktop\SharpCap Captures\darks\ZWO ASI178MC\RGB24@3096x2080\3.1s\gain_200\dark_10_frames_24.0C_2019-05-07T03_06_51.png
#Black Point
Display Black Point=0
#MidTone Point
Display MidTone Point=0.452173913043478
#White Point
Display White Point=1
TimeStamp=2019-05-07T03:10:59.9990325Z
SharpCapVersion=3.2.5986.0
TotalExposure(s)=62.02026
StackedFrames=20

BlackWikkett
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Re: Camera or Pro License Problem??

Post by BlackWikkett » Wed May 08, 2019 3:24 am

In the Live Stack window below the display is Align Frames checked? Are you guiding?

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admin
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Re: Camera or Pro License Problem??

Post by admin » Wed May 08, 2019 6:21 am

Hi,

Yes, definitely check that the align option is ticked in the live stacking UI, since the images show looks like it has been stacked without alignment. Once you've checked that the align option is ticked you should also keep in I on the status and star detection information to make sure that enough stars are being detected to align each new frame.

Cheers, Robin

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Re: Camera or Pro License Problem??

Post by turfpit » Wed May 08, 2019 8:30 am

Carl

Several things stand out to me in your last post.
  • How to run/use the Snipping Tool?
  • Show Live Stack settings in a forum post?
  • Are dark frames working for you?
  • Are you correctly focused and how to achieve this?
I have broken down some guidance into separate posts which follow on from here.

Dave

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turfpit
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Re: Camera or Pro License Problem??

Post by turfpit » Wed May 08, 2019 8:42 am

Carl

Running the Snipping Tool.
  • In the Search Bar [1] (bottom left in Windows 10 which I think you are using) start typing snipping tool [2].
  • The option for Snipping Tool [3] appears, click on this.
  • Click on the New button, the screen goes faint.
  • Hold down the left mouse button and drag out a rectangle. This screen area will be saved to the clipboard and is displayed.
  • Save the screen snip in a file (floppy disk icon in toolbar).
  • The saved file can be attached to a forum post (see Attachments tab below the forum post being written), either as a file or displayed inline in the text of the post.
snipping-tool.png
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new-snip.png
new-snip.png (16.11 KiB) Viewed 91 times

Dave

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turfpit
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Re: Camera or Pro License Problem??

Post by turfpit » Wed May 08, 2019 9:01 am

Carl

Live Stack settings.
  • Start Live Stack.
  • Check Align Frames in the left hand pane.
  • On the Alignment tab, check Highlight Detected Stars (boxes will be drawn around stars). From the manual Yellow stars are used for alignment, red are not used for alignment. This can be very helpful to determine and understand the causes of problems with star detection and alignment.

live-stack-settings.PNG
live-stack-settings.PNG (44.98 KiB) Viewed 90 times

Dave

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turfpit
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Re: Camera or Pro License Problem??

Post by turfpit » Wed May 08, 2019 9:33 am

Carl

This post is a way for you to ensure that you are following the Dark Frame processes and they are working for you and being applied correctly. This test can be done on the bench using just a camera and laptop. I have used a ZWO ASI120MC. The gain (50%) and exposure (30s) are deliberately set higher to force the production of hot pixels. Your camera being less noisy might need higher gain and exposure to see the hot pixels. The camera used in the test has the cap fitted.

Follow the pictures below. Maybe post back your image 1 and 7 from the test.

1. Shows the hot pixels.
2. Create a Master Dark.
3. Master Dark location/name shown in Notification Bar.
4/5/6. Select and activate the master dark.
7. Master dark applied - notice that the image is perfectly black (no hot pixels). This proves the creation and application of a master dark is working correctly.

1.PNG
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2.PNG
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3.PNG
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6.PNG
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7.PNG
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Dave

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turfpit
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Re: Camera or Pro License Problem??

Post by turfpit » Wed May 08, 2019 10:00 am

Carl

For Live Stack (or any imaging), good focus is essential in order to attain good outcomes. Personally, I use a Bahtinov Mask - a cheap (~£20) and simple way to achieve a good focus. If you purchase one, it must be of the correct size to fit over the end of your telescope (dictated by the diameter of the scope). When focus cannot be achieved by placing the camera directly in the eyepiece holder, then usually additional spacers are required but this is not the first step.

You might want to post back your focused star with the mask in place - hint, this is where the Snipping Tool comes in handy.

In this example, I have used the bahtinov mask against Arcturus to achieve focus. Arcturus is probably too bright and ideally a medium brightness star (for example Denebola) would be a better choice (however at the time Arcturus wasn't covered by cloud). There are 2 lines which form an 'X'. A third line will move as the focus knob is turned. For good focus the single line must lie at the intersection of the 'X'. Additionally, at good focus, 3 parallel lines will be visible if the capture program has Zoom set high (over 100%), the exposure is increased lightly and the image is stretched to show fainter detail (Display Histogram Stretch).
  • Choose a star which is close to the deep sky object of interest. This minimises slewing which may flex the optics (think meridian flips), makes for focusing with similar sky glow/light pollution and altitude (think atmospheric diffraction).
  • Slew to a suitable star.
  • Hang the Bahtinov Mask over the end of the telescope.
  • Set Zoom to 100% or greater [1].
  • Start off with exposure about 1s [2]. This way you are not waiting around for an updated display.
  • Once the 3 lines intersect, then apply a Display Histogram Stretch [3] by clicking the button [4]].
  • Keep adjusting fine focus until the 3 parallel lines appear.
  • Increase exposure to a higher value and lock down the focuser (if applicable).

Arcturus-focus-with-bahtinov-mask.PNG
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Note in this picture, although Arcturus may look slightly saturated, there are other fainter stars which are well defined but would not be visible with a low exposure setting and the Display Histogram Stretch turned off.

Arcturus-focused.PNG
Arcturus-focused.PNG (220.58 KiB) Viewed 87 times


Dave

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