How to Improve My Jupiter

[JSeaman]

Hi there,

I am finally getting back into things after the usual Summer months off and started with Jupiter. Whilst the picture isn't terrible, it's not great either, so here is the set up

 

- ZWO ASI 224MC, should be a good camera for planetary

- 300PDS scope, 12", all the aperture I need (collimated and focused electronically)

- 2x barlow lens to give a 3,000mm focal length

- Bortle 5, not great but, hey, it's planetary, should be adequate

- 30 seconds of .SER footage (8 bit) and best 30 frames, not sure if I could do better with this?

- Stacked in autostakkert and registax for some wavelets

 

So, what's the best thing I can do to improve the quality of this image?

 

James

[vlaiv]

19 minutes ago, JSeaman said:

30 seconds of .SER footage (8 bit) and best 30 frames, not sure if I could do better with this?

30 seconds is way short capture.

If you stacked only 30 frames and got that much SNR - it points to your subs being too long.

You'll have much more difficulty sharpening the image if you let atmosphere "dance" during single exposure and create motion blur.

What you want to do is have short enough exposure to freeze any motion of atmosphere. This will help software select best frames as well as it will be much clearer where seeing is good and where it's not.

Use exposure of 5ms (regardless of what preview looks like - if it is too dim or if histogram does not look good) and shoot 3-4 minute video at smaller ROI - like 640x580 to achieve higher FPS.

You want to end up with at least 20000 frames in your ser. Then select best few percent and stack those (best 2% will give you 400 subs to stack for example).

[JSeaman]

Thanks Vlaiv, was hoping you would chip in

It's been so long since I've done planetary I can't remember how I did it! 

I think my frame length was 0.002 seconds (but will check later), I'll give 5mS a go and several minutes, thanks for that

Not sure how I do smaller ROI but I'll have a play with KStars later and see if I i can find it

[vlaiv]

23 minutes ago, JSeaman said:

Not sure how I do smaller ROI but I'll have a play with KStars later and see if I i can find it

What do you use for capture?

Best to use SharpCap or FireCapture for planetary.

[JSeaman]

I'm on astroberry and using the kstars software for everything at the moment

[vlaiv]

3 minutes ago, JSeaman said:

I'm on astroberry and using the kstars software for everything at the moment

That might be limiting factor.

Real benefit of modern planetary cameras is ability to do very high FPS, but in order to do that several things must be optimized. Software needs to be written with planetary imaging in mind, computer must be able to handle full usb 3.0 speeds and storage should be able to record data at those transfer rates.

You want to record at at least 150-200fps or higher if possible. If you record at 150fps for say 200s (a bit more than 3 minutes) - that will result in 30000 subs.

I'm not sure what planetary capture software is compatible with astroberry, so that is worth looking up.

Oh, here we go - this is from astroberry website:

• oaCapture for planetary imaging
• FireCapture for planetary imaging

Maybe look up one of those two for planetary imaging?

[JSeaman]

Ace thanks, I'll take a look!

 

[JSeaman]

OK so firecapture seems to be the worst of the 2 and crashes fairly regularly

oaCapture seems more stable but also crashes when recording

Neither seem to be able to maintain a high frame rate (SER or AVI) , with 640x480 ROI I can get up to about 70fps but it won't maintain that recording, it's very stop/start. I checked RAM and CPU, both are showing light usage, not sure what could cause this

I have to limit the USB traffic setting to ~50-60 for it to work at all as well

 

[vlaiv]

What computer are you using? Is that RPI with astroberry or something more powerful?

[JSeaman]

Yes a Pi4, switched over a year ago and cured all my issues ... until now!

[vlaiv]

It is quite ok solution for deep sky imaging where you don't have nearly as much requirements for data transfer speeds, but not sure if it is good solution for planetary.

Maybe you'll need some sort of laptop for planetary role.

[JSeaman]

Ah that's a shame, it's quite possibly the first time I have used it for planetary actually

I just did an update and the latest version of firecapture is much more stable. I have managed to get ~20 fps with Jupiter in the fov, just waiting for a tree to get out the way so I can see if it is any good!

[vlaiv]

1 minute ago, JSeaman said:

Ah that's a shame, it's quite possibly the first time I have used it for planetary actually

I just did an update and the latest version of firecapture is much more stable. I have managed to get ~20 fps with Jupiter in the fov, just waiting for a tree to get out the way so I can see if it is any good!

It might be worth experimenting with recording options - SSD attached to USB3.0 port, or maybe SSD backed NAS on a gigabit network?

SD card storage is painfully slow.

[JSeaman]

That might be an interesting experiment. The tree is pretty well out the way but this is the quality of the image:

 

 

I have run a 3 minute video with 350 gain and 5mS, will see how that turns out ...

[JSeaman]

Not a great start...

 

[JSeaman]

So the offset bottom appeared in one of the first frames, scrolling forward through the stack in autostakkert made it choose a new reference frame and that problem went away

It has certainly changed my output but we're not in the 'good' category yet ...

I'm finding now the tree has passed it's too bright so I have stayed with 5mS and dropped the gain to 150 and trying again now

[vlaiv]

When you stack - do several stack at once (you can do that by entering multiple percentages in AS!3) - like top 5%, 10%, 20%, 40% frames - just to see the difference that makes.

[JSeaman]

OK will give that a try, I have just gone through focusing again and Jupiter's also in a better place now so this next one looks like an improvement. I'll try top 5% then top 10% again

[JSeaman]

Obviously getting better (Thanks again for the help!) but I have artefacts from the bad first frame which appears in the SER file. PIPP can't open it so I'm trying an AVI to see if that works 

 

[JSeaman]

I still see the corrupt frames in an AVI but I can open this in PIPP

In PIPP, I tried using a quality reduction and also exporting after the first 20 frames but both still show frames as bad in Autostakkert. 

I tried 'limit frames' in Autostakkert and that didn't improve things. 

I then found you can press space bar on specific frames (first and last in my case) to exclude them from the stack and that fixed it

So finally, this is the best 75% of 2,345 frames in PIPP then the best 10% and then 5% in Autostakkert followed by some Wavelet processing in Registax, a big step forward!

 

 

That will do for now - many thanks for the help Vlaiv

[JSeaman]

The final image ...

[Altocumulus]

Impressive.  Three moons too?

I've learnt a thing or two reading this, thank you.

Apart from the odd moonshot I've only done solar, so that experience I carried over into my first Jupiter earlier this week. I'd hazard a guess my first error was in only taking 1-2k fast frames. Next time it'll be in the 10-20k ball park!

Plus my first time with an OSC! 

[Andypeck101]

Really usefull discussion as I'm trying to get a handle on planetary as well and I think I could get some siginificantly better results using the suggested settings.

I'm curious though, @vlaiv Would the same 5ms rule still be true for a dimmer target such as Mars?