Dark universe swamped by colured pixels

Discussions of Electronically Assisted Astronomy using the Live Stacking feature.
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admin
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Re: Dark universe swamped by colured pixels

Post by admin » Mon Apr 27, 2020 6:07 pm

Potentially you have used different settings (more gain?) this time than the last time around.

From talking to various dealers who sell cameras and lots of users who try to get them working, I'd say that ZWO actually do pretty well on hardware quality and on robust software. There have been some issues with the older models like the 120 MC not working so well with the latest PCs/software/drivers, particularly for longer exposures. However since the sensor is fairly noisy anyway that's not the end of the world. The new USB3 models seem to be very reliable.

Cheers, Robin

julietdiane
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Re: Dark universe swamped by colured pixels

Post by julietdiane » Thu May 07, 2020 1:42 pm

I tried again with dark frame subtraction and reduced gain, no guiding, see:

https://photos.google.com/photo/AF1QipM ... 3rh2bvBWJB

[ZWO ASI120MC]
Debayer Preview=On
Pan=0
Tilt=0
Output Format=PNG files (*.png)
Binning=1
Capture Area=1280x960
Colour Space=RAW8
Temperature=2.7
Discard Split Frames=Off
High Speed Mode=Off
Turbo USB=80(Auto)
Flip=None
Frame Rate Limit=Maximum
Gain=63
Exposure=12.503455
Timestamp Frames=Off
White Bal (B)=25
White Bal (R)=54
Brightness=5
Auto Exp Max Gain=50
Auto Exp Max Exp M S=30000
Auto Exp Target Brightness=100
Mono Bin=Off
Banding Threshold=35
Banding Suppression=0
Apply Flat=None
Subtract Dark=C:\Users\mail\OneDrive\Desktop\SharpCap Captures\darks\ZWO ASI120MC\RAW8@1280x960\11.8s\gain_52\dark_20_frames_7.2C_2020-05-02T19_51_54.fits
#Black Point
Display Black Point=0.28515625
#MidTone Point
Display MidTone Point=0.455934506766061
#White Point
Display White Point=0.8359375
Notes=
TimeStamp=2020-05-02T21:59:54.5976713Z
SharpCapVersion=3.2.6298.0

I realise the my histogram colours are amiss, I used the auto colour balance and auto stretch?

As you can see from my image the colour pixel corruption is still visible.

I was going to try again but my az-eq6 mount decided to play up, both axis stop now slewing after a few seconds and freeze up

making a horrible grinding whining noise. Since both motors are doing it I don't think it is motor problems and the only

common link to both motors is the control board, which is going to hurt financially.

I was looking at cooling the asi120 with a Geoptic cooling fan https://www.rothervalleyoptics.co.uk/ge ... g-fan.html

but this has to wait until my slewing problems are dealt with.

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Re: Dark universe swamped by colured pixels

Post by turfpit » Thu May 07, 2020 2:27 pm

From the capture settings the dark is:

Subtract Dark=C:\Users\mail\OneDrive\Desktop\SharpCap Captures\darks\ZWO ASI120MC\RAW8@1280x960\11.8s\gain_52\dark_20_frames_7.2C_2020-05-02T19_51_54.fits

exposure = 11.8s, gain = 52, temperature 7.2C

From the capture settings:

Temperature=2.7
Gain=63
Exposure=12.503455

The lights and the master dark do not match - this will not help. Try this:
  • decide on the gain/exposure to be used
  • create a master dark using these settings
  • apply the dark to frames stacked using the above settings
Once that difference is eliminated then post back the results.
Since both motors are doing it I don't think it is motor problems and the only
common link to both motors is the control board
The other common link is the power. How are you powering the mount and have you a way of using an alternate power source?

Dave

julietdiane
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Re: Dark universe swamped by colured pixels

Post by julietdiane » Thu May 07, 2020 4:46 pm

Thanks Dave, yes I spotted my darks/lights mismatch and I was hoping to fix this similar

to what you have suggested but then the slewing problem popped up.


I agree a dodgy power source could result in problems with both slewing motors, however I have a trusted mains

based power supply - Maplin XM21X Regulated power supply with 13.8V DC output.


It will take me some time before I get back, besides fitting a new motherboard I will strip down cleanup

and re-grease the mount.

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