Jupiter on a Startravel120

[JayPea]

Hi,

I managed to have a first go at Jupiter on Saturday using the video frame staking method. I have a simple Skywatcher Startravel 120 and I've recently bought a ZWO ASI290 MM uncooled. I can attach it to a Nikon mount through a DIY adapter and using that I attached it to a Nikon x2 teleconverter and then that to the scope giving a total of 1200mm. That gets me ~70 pixels across Jupiter.

 

To start with I was just experimenting to get the thing in focus and recording. The scopes focus has loads of tube play/slop so as you rotate the wheel the image goes out of view top and bottom. Drives you mad and makes fine focus all but impossible on such a magnified image (I've since improved the play a lot).

 

The video image looked poor to me and I wasn't sure it was at optimal focus but it was a test of the connections and set up really. So I ran a 1 min clip anyway. All looked to be working but the videos look a lot worse than I expected. So I dismantled the adapter and put a contrast booster in to start with. I was going run through my filters. Now the image was a blurry smudge, Jupiter had dipped just behind the branches of a tall bush. So getting frustrated I gave up and came in.

 

But to test the process I ran them through AutoStakkert anyway. WOW! out popped a clean Jupiter. Finding it hard to believe the apparent details revealed were real features I checked with the Java Jupiter webpage and got the expected view for that time. The GRS should be bottom right. I then Googled an image in similar orientation (thanks NASA) and compared. I think I can convince myself I've picked up some of the smaller features. I'd be interested to see other peoples before (video frame) and after comparisons. Is my video still typical or should I expect better?

 

I had 6617 frames and found that using anything between 25%-75% produced the best images, lower than that had too much noise. Next steps are to nail the focus and try and get a clearer less noisy video image.

 

Below is a 100 percent crop screen shot of a still frame used and a 100 percent crop of a final stack (a 75% one - only tweaked to increase the contrast a bit. 3 moons are faint). For comparison I scaled down the NASA image and put it side by side. Amazing what detail you can reveal from the stacking.

 

Not what I expected for a quick and dirty test. Makes a change from the usual routine of stacking my DSO images and still not being impressed!

John

For those interested the camera settings below:

[ZWO ASI290MM]
Pan=568
Tilt=248
Output Format=SER file
Binning=1
Capture Area=800x600
Colour Space=MONO16
Temperature=35.3
High Speed Mode=Off
Turbo USB=100(Auto)
Flip=None
Frame Rate Limit=Maximum
Gain=300(Auto)
Exposure=0.0016
Timestamp Frames=Off
Brightness=1
Gamma=50
Auto Exp Max Gain=300
Auto Exp Max Exp=30
Auto Exp Max Brightness=100
Subtract Dark=None
Display Brightness=1
Display Contrast=1
Display Gamma=1

[Bobby1970]

You have got to be happy with that result. I have a ST120 myself and have used it on the moon but never a planet. I had a go with my ST80 on Jupiter just for the fun of it really. I might try the 120 next. It's good to see what you can capture with the "wrong" equipment in my opinion. 

Well done. 

[michael.h.f.wilkinson]

Very nice result!

[philj]

Thats a good ST120 planetary image, well dne. I remember about 15 years ago doing the same with my ST120 on EQ3 mount, didnt quite get the same quality s this image though due to my poor techniques and cheapo web camera at the time.

[Alan White]

That's wonderful.

10/10 for your patience and perseverance.

Says a lot for a good old basic ST scope.

[Stu]

Very impressive image given the kit limitations! I've seen worse with more 'ideal' kit used so you should be well pleased!

[Dave Lloyd]

Yes, you need to be proud of that.

[JayPea]

Thanks for the encouraging comments.

 

I went out briefly the following night and tried again with a little colour USB sensor board (3.75um Aptina AR0130 1.3MP). Unfortunately I stripped the thread on the 1.25" mount and it wobbled too much and drooped so that stopped play early. I also had loads of dark spots from sensor dust. Being USB 2 and colour the frame rate was way slower. But I managed a recognisable disc as Jupiter. But no detail as the resolution was lower as the sensor pixels were larger than my mono sensor. Nothing to write home about.

 

Then it struck me I have a L and a RGB image I could blend and give the mono image a boost. So I rotated and enlarged the colour image to match the mono one and used a simple luminance blend layer in Photoshop Elements to combine them (L and RGB blending).

 

Result below with the colour Jupiter I used for RGB. I think the technique has some potential especially if I can get a better colour images at the same time.  As I don't have RGB filters or filter wheels it will have to do!

 

So I've been pleasantly surprised by the results, so much so I proudly showed the mother in law. "Very nice, is that the moon?". That reminded me I shouldn't get too carried away with them!

 

I've since fixed the focus droop/slop, stripped threads, cleaned sensor marks and I now know where best to place the scope for a better view. So I'll keep trying.

 

John

[Mr niall]

I'm pretty sure I understood at least 4% of that  but those are some pretty brill shots lovely stuff. I think the main thing holding me back from buying a camera is the fact that I will almost certainly not be intelligent enough to figure out how it works!

[happy-kat]

Your mono image is brilliant really nice and I much prefer it to the colour blended image.