Disappointing images of Jupiter...

[tooth_dr]

I'm really struggling to get anything remotely decent from Jupiter, and I'm wondering whether it's me or the equipment or the atmosphere?  I've tried a couple of 8" scopes and nothing really much difference.  (VC200L FL=1800mm F9 is brand new and should be well collimated and I've collimated my SW 200P FL=1000mm F5 pretty accurately using OCAL collimator).  I have an EFW with LRGB and 685nm IR, and am using a 120MM mini.  I've tried without barlow and with 2x and 3x barlow.  I am using the Celestron XL range of barlows.  I focused on a nearby star using a Bhatinov mask, and rechecked the focus on one of the moons using the mask also.  I appreciate the camera is very basic, it's a guidecam I replaced for a 290MM.

I've been out three nights over the past ten days, including a few hours last night, and not getting anywhere.  I've attached a video (red filter) for anyone to have a look at and advise what I might be able to do to improve.  I have tried MONO16 and it didnt seem to yield any improvement.

 

Cheers!

 

Stats:

[ZWO ASI120MM Mini]
FrameType=Light
Pan=0
Tilt=266
Output Format=SER file (*.ser)
Binning=1
Capture Area=496x512
Colour Space=MONO8
Temperature=8.7
Discard Split Frames=Off
High Speed Mode=Off
Overclock=0
Turbo USB=86(Auto)
Flip=None
Frame Rate Limit=Maximum
Gain=48
Exposure=20.6560ms
Timestamp Frames=Off
Brightness=0
Auto Exp Max Gain=50
Auto Exp Max Exp M S=30000
Auto Exp Target Brightness=100
Trail Width=3
Minimum Trail Length=100
Trail Detection Sensitivity=9
Remove Satellite Trails=Off
Background Subtraction=Off
Planet/Disk Stabilization=Off
Banding Threshold=35
Banding Suppression=0
Apply Flat=None
Hot Pixel Sensitivity=5
Subtract Dark=None
NegativeDisplay=0
Display Black Point=0
Display MidTone Point=0.5
Display White Point=1
Notes=
ZWO FilterWheel (1)=Red
TimeStamp=2023-11-08T21:32:15.3699137Z
SharpCapVersion=4.0.9538.0
StartCapture=2023-11-08T21:32:15.3584930Z
MidCapture=2023-11-08T21:32:25.6994930Z
EndCapture=2023-11-08T21:32:36.0397134Z
Duration=20.681s
FrameCount=1000
ActualFrameRate=48.3530fps
TimeZone=+0.00
 

 

21_32_15_Red.ser

[Kon]

Nice capture despite what you say. IThe weather has just been awful the last few weeks. I have near nothing like this for a long time. My only advice, drop the mask and focus on the planet until you tease some fine details.

Regarding the exposure come down to 7-10ms. 20ms will not freeze the atmosphere and it will increase your fps a bit too. The 20s capture is rather short; for Jupiter 1-2 min should be ok without smearing so you can have more images to stack and reduce the noise.

I took your ser in as!3, 50% frames and then in astrosurface. For this weather that's a nice capture.

[tooth_dr]

7 minutes ago, Kon said:

Nice capture despite what you say. IThe weather has just been awful the last few weeks. I have near nothing like this for a long time. My only advice, drop the mask and focus on the planet until you tease some fine details.

Regarding the exposure come down to 7-10ms. 20ms will not freeze the atmosphere and it will increase your fps a bit too. The 20s capture is rather short; for Jupiter 1-2 min should be ok without smearing so you can have more images to stack and reduce the noise.

I took your ser in as!3, 50% frames and then in astrosurface. For this weather that's a nice capture.

Thats really impressive, thanks for doing that, and thanks for the recommendations.

I read that gain 48 was best for the 120MM, so I set that and then adjusted exposure.   Would it be ok to set the exposure and adjust the gain instead?  Should the histogram be quite low too?  I'm using SC, and the histogram is sitting at about 1/4-1/3 the way across.

 

 

[Laurin Dave]

Hi Adam.. I had a look too and got a similar sharpened result to Kon..  as he says seeing has been poor recently ..   I'd suggest upping gain to get 10ms and aim for 70% on the histogram ..  and see what you get 

Dave

[Kon]

4 minutes ago, tooth_dr said:

Thats really impressive, thanks for doing that, and thanks for the recommendations.

I read that gain 48 was best for the 120MM, so I set that and then adjusted exposure.   Would it be ok to set the exposure and adjust the gain instead?  Should the histogram be quite low too?  I'm using SC, and the histogram is sitting at about 1/4-1/3 the way across.

 

 

Don't worry too much about the gain. You are stacking thousands of images and you can suppress any noise. I usually aim histogram of 70 but I have recently moved to 90-95% with my mono and it brings a lot more signal with less noise. You take a look on my recent post on Uranus.

[symmetal]

Set the exposure to 5ms to help 'freeze' the seeing and will also allow a higher framerate. 20ms is too long really.

Set the gain very high. It will look awfully noisy on the preview but don't worry about that as stacking hundreds of frames will fix that. Using the gain try to get the histogram max value between 50% and 75% but it doesn't matter if it's lower.

Set camera 'high speed mode' to on. This will almost double your framerate. High speed captures use 9 or 10 bits resolution rather than the camera default of 12 bits. As you're recording in 8 bit that won't affect the quality. Stacking will increase your actual 8 bit resolution to around 12 bits anyway. For this reason don't select 16 bit recording as it'll have no effect on image quality but will reduce your frame rate. The ASI120 mini is USB2 only so not sure what you're max framerate will be, but 200fps is normal using USB3 with a planet sized ROI.

The brightness setting is the camera offset. Setting it to 0 will likely clip your sky background so increase it until the histogram peak, (the sky background) is just clear of the left edge of the histogram. Using a high gain it may not be easy to see through all the noise, so reduce the gain while checking it.

Duration can really be up to 2 minutes for Jupiter, due to planet rotation, and longer if you don't have perfect seeing or a large scope, so 3 or 4 mins should also be fine and give a better chance of getting enough good frames to stack.

It's not in your list, but ensure gamma is off in camera settings. Having it on will significantly reduce your frame rate.

Alan