Atmospheric dispersion or something else?

[turboscrew]

Last night I had yet another try with my OrionOptics VX12. Tried to see Jupiter, saturn and some DSOs in Cygnus.
The session took about one hour followed bu about 1.5 hours of heavy cursing.
I didn't see any DSOs, and I imagine that the sky was not dark enough yet, I saw Jupiter and, I think, 4 moons, and I saw Saturn, but the images were terrible.

With 10 mm eyepiece (120X)I saw something like this:
https://www.cloudynights.com/uploads/mo ... 805639.jpg
Is this normal given the conditions, or is there something wrong with my gear?

The seeing was supposed to be quite good, but Saturn was about 7 degrees above the horizon.
Meteoblue ( https://www.meteoblue.com/en/weather/ou ... and_644450 )
gave 5 for seeing index 1 and 4 for seeing index 2.

[sdbodin]

Yup, sounds about right, I don't look at anything 7 deg above the horizon. Haven't looked at either Jupiter or Saturn this year and they are 20 deg above my horizon, and don't plan to either. Just an exercise in frustration.

Steve

[turboscrew]

Yup, sounds about right, I don't look at anything 7 deg above the horizon. Haven't looked at either Jupiter or Saturn this year and they are 20 deg above my horizon, and don't plan to either. Just an exercise in frustration.

Steve

Phooh, that's a relief.
This was the 3rd time I took the tube out - the weather Gods haven't been good to me.
I'm still figuring out how the thing behaves.

I also learned that I really need a tracking EQ mount. With 10 mm eyepiece , I didn't even get it focused when Saturn was out of the FOV. And my Dobson is not that smooth to move. It's a bit sticky causing big overshoots in adjustments.

[turboscrew]

BTW, I wonder if the linked picture is turned around? I think in my "upside down" view, the red was above and the blue below. The general blurriness was the same.

[John Baars]

BTW, I wonder if the linked picture is turned around? I think in my "upside down" view, the red was above and the blue below. The general blurriness was the same.

You are right.
Blue rays on top, red at bottom. In a Newton reversed.
The colors as well as the blurriness can be corrected by a athmospheric Dispersion Corrector. It works quite well in refractors with their long focus range. In a Newton one must be careful and ask the dealer how much focus-travel is added.
https://agenaastro.com/zwo-1-25-inch-at ... r-adc.html

[turboscrew]

BTW, I wonder if the linked picture is turned around? I think in my "upside down" view, the red was above and the blue below. The general blurriness was the same.

You are right.
Blue rays on top, red at bottom. In a Newton reversed.
The colors as well as the blurriness can be corrected by a athmospheric Dispersion Corrector. It works quite well in refractors with their long focus range. In a Newton one must be careful and ask the dealer how much focus-travel is added.
https://agenaastro.com/zwo-1-25-inch-at ... r-adc.html

Good to know. I had a brief look, but decided to leave the atmospheric dispersion connectors for later.

[Baurice]

I've managed to get Jupiter's two main cloud belts and Saturn's rings (but not the Cassini Division) but it has been tough.