Observing Jupiter with a spotting scope (1 Viewer)

[BoldenEagle]

Yesterday evening I tried to observe Jupiter here in central part of Finland. Weather was clear but some air currents were deteriorating the seeing. Nevertheless I had maybe the best views of Jupiter so far using my Kowa Tsn-883 spotting scope with the 1.6x extender. Two dark bands were showing quite clearly (most times before they have been very difficult to see at all) and I managed to get some pictures with my smartphone, which are showing the bands.

Regards, Juhani

 

[dantheman]

Nice! I was going to ask if they were moons with it, but zoomed in and realised it was dirt on my laptop screen (oops)

Can I ask - which planet is currently quite near the full moon in the sky and rising roughly with it?

 

[BoldenEagle]

Nice! I was going to ask if they were moons with it, but zoomed in and realised it was dirt on my laptop screen (oops)

Can I ask - which planet is currently quite near the full moon in the sky and rising roughly with it?

There were 4 moons showing, even with 10x binocular. Because the planet was so bright I had to underexpose the picture so much that the dimmer moons are not visible in the picture.

Your description sounds like Jupiter; it's showing on the right side of the moon at east-southeast direction.

Regards, Juhani

 

[tenex]

Jupiter was quite close a couple of days ago but the moon is lagging ever more behind it. Any binocular should show several moons if in doubt.

I was able to see those two dark bands lately from my home with my Meopta S2 at 60x (or 88x which wasn't much better due to poor seeing). But where is the chromatic aberration (orange/blue) coming from, surely not your scope?

 

[BoldenEagle]

But where is the chromatic aberration (orange/blue) coming from, surely not your scope?

I'm afraid it is from the scope.

See here: ATX95 chromatic aberration etc.

I have been in the impression that longitudinal chromatic aberration is not a sample dependent aberration and that Kowa 883 doesn't suffer from it, but for me it seems that this is not completely true.

It's nothing new though because I think Jan Meijerink has pointed this out long ago in his test reports:

Spreiding in optische kwaliteit bij telescopen (KOWA TSN-883)

Spreiding in optische kwaliteit bij telescopen (KOWA TSN-883)

tvwg.nl

Regards, Juhani

 

[has530]

Any binocular should show several moons if in doubt.

Truly any, just for fun I had a bunch out looking at jupiter and even my vintage compacts showed the moons with ease.

And then I too was able to see some banding with my cheap (~$200) spotting scope with a few different eyepieces.

 

[jring]

I have been in the impression that longitudinal chromatic aberration is not a sample dependent aberration and that Kowa 883 doesn't suffer from it, but for me it seems that this is not completely true.

Hi,

the longitudinal (or axial) CA is the one which makes the image mushy above a certain magnification, not the one showing orange/purple fringes. Those are from lateral (or transversal) CA.

All telescopes suffer from varying amounts of CA, unless you look at a pure mirror telescope like a Newtonian and ignore the eyepiece. The Kowa fluorite scopes are known for having low CA which is usually not noticeable, unless you specifically look for it.
Also when digiscoping, lateral CA can also be introduced by the camera lens.

Cheers,

Joachim

 

[BoldenEagle]

Hi,

the longitudinal (or axial) CA is the one which makes the image mushy above a certain magnification, not the one showing orange/purple fringes. Those are from lateral (or transversal) CA.

All telescopes suffer from varying amounts of CA, unless you look at a pure mirror telescope like a Newtonian and ignore the eyepiece. The Kowa fluorite scopes are known for having low CA which is usually not noticeable, unless you specifically look for it.
Also when digiscoping, lateral CA can also be introduced by the camera lens.

Cheers,

Joachim

Hi Joachim,

So Kowa 833 (or at least some samples) have lateral CA at the image center? Is lateral CA dependent on the scope body or only the eyepiece? Why some samples of 883 seem to have it and others not (referring to Jan Meijerink's test images which clearly shows some samples have quite strong fringes)?

Darkish raptor far away against light grey clouds is hard test for CA but I was little dissappointed to 883 performance when I saw purple fringing (which prevents seeing birds upperwing colouring accurately) as it is so often mentioned that 883 has so good CA control. I don't remember Leica Televid 82 had same kind of issues at the image center, closer to the edges there was growing fringing of course.

Regards, Juhani

 

[Owene]

Sorry this is a bit late. I had great views of Jupiter and (I think) 4 moons with my swaro atm80. Took me a while to get the focus right to stop light diffusion but very nice pin sharp images with a lot of the detail visible

 

[Mark9473]

But where is the chromatic aberration (orange/blue) coming from, surely not your scope?

I'm afraid it is from the scope.

No that is not correct.
The image you posted is showing the classical view of atmospheric dispersion.
This is the atmosphere affecting your view because the planet is too low over the horizon.
In an astronomical telescope in can be corrected with an "atmospheric dispersion corrector" (ADC) but in a spotting scope you won't have enough back focus to use it.

 

[BoldenEagle]

No that is not correct.
The image you posted is showing the classical view of atmospheric dispersion.
This is the atmosphere affecting your view because the planet is too low over the horizon.
In an astronomical telescope in can be corrected with an "atmospheric dispersion corrector" (ADC) but in a spotting scope you won't have enough back focus to use it.

Thanks! Would that explain also why there is different colours than the CA I see in daylight with my scope (orange and blue vs magenta and yellow)?

I didn't notice same colours with Saturn that evening allthough it was equally low, does it depend how bright the object is?

Regards, Juhani

 

[Mark9473]

Yes, and yes.