Jupiter in Carl Zeiss Telementor II

[glennbech]

I put my three Kids and better half to bed at 9 last night and packed the car. I have access to a small cabin deep in the Norwegian forest that has a decent sky. Far from perfect, but a whole lot better than home, and only 30 minutes by car. 

I brought my grab-and-go Megrez 90mm on a Vixen Portal II for some deep sky observation and the Carl Zeiss Telementor II scope mostly for fun. 

I am a very novice observer, but I include Jupiter in most of my observation sessions and have come to a conclusion that is probably entirely wrong, and I will let you guys correct it. 

It seems to me that it doesn't really matter what kind of scope you use for Jupiter. The quality of the view will mostly / almost / all of the time be limited by seeing.    

I have watched the planet in a Skymax 150 mak, Megrez 90mm doublet apo, 8" reflector and now my Carl Zeiss scope. 

I have not seen the planet give away anything other than two equatorial bands. 

Last night was actually my best ever observation of Jupiter. It was through the Zeiss Telementor and I could clearly make out structure and textre in the bands. The Zeiss 5mm Ortho Eyepiece gives a magnification of x168, pushing the limits of the 2.5", but  provided by far the best view.    

My telementor has no diagonal, and I mount it with tripod legs at maximum length. This gives a comfortable viewing position. I can just stand casually and relax at the eyepiece when Jupiter has gained some height.  

But back to my point. Would the view have been better if I looked through an 8" reflector or 6" mak at that point in time? Or is the planet deciding for itself what details to receive? 

 

[John]

It will all depend heavily on the seeing conditions. If they are poor I stuggle to see more than the main 2 bands with any of my scopes (4", 4.7" and 12"). Under moderately good conditions I can see the sort of detail in this sketch I made with my ED120 refractor a few years back (the long dark feature in the NEB is a barge, not the GRS):

[glennbech]

12 minutes ago, John said:

It will all depend heavily on the seeing conditions. If they are poor I stuggle to see more than the main 2 bands with any of my scopes (4", 4.7" and 12"). Under moderately good conditions I can see the sort of detail in this sketch I made with my ED120 refractor a few years back (the long dark feature in the NEB is a barge, not the GRS):

 

1

That's an awesome observation!

The question is if you would have seen the same detail in the 4" on that night?

[John]

4 minutes ago, glennbech said:

....The question is if you would have seen the same detail in the 4" on that night?

Possibly, but I'd have to have worked harder and observed for longer to tease it out.

Many, many years ago I borrowed my 1st astro scope from a mate - a 60mm refractor which was decent but almost certainly not of the quality that your Telementor is. I observed Jupiter for a couple of weeks one summer with that scope sketching the details each evening. This was around 30 years ago but what is notable is that the amount of detail that I was seeing gradually improved in the sketches as time went by and my observing skills increased. I never saw the GRS with that scope but generally more cloud belts were showing in each sketch in the series. I think the best result with that scope showed 5 or maybe 6 belts.

I've had rare nights where you just don't need to try and the planets detail just jumps out at you in practically any scope. More often though you feel like you are almost digging the detail out of the disk, waiting for those little moments of steady seeing when your eye quickly tries to catch as much as possible before the clear atmospheric cell passes over and the image looses it's edge again for a while.

Goodness knows why we do it, especially in the UK climate, but it's strangely addictive  !

 

[Stu]

Very difficult questions to give definitive answers to. I've been getting similar views from my 4" Tak recently, possibly better in some ways but the seeing has been excellent so comparisons are tricky.

I know that I've seen shadow transits and the GRS in a 60mm Tak and a 66mm William Optics SD so it is possible, but it is challenging, and certainly there is more detail in a 4".

The other night I observed with the Tak alongside a good 10" f6.3 scope and there wasn't much in it, more colour in the dob but a sharper image in the Tak. Seeing was pretty good.

Some years ago, I was in a group with my 8" Mak, something like a 12" dob or bigger and a little Meade scope. The Meade was giving the best images of Saturn out of the three!

My 16" has probably given me the most detailed Jupiter image I've seen, but you do need good seeing for that to happen.

[laudropb]

I certainly find that seeing is the defining factor. I have had views similar to Johns sketch with my 4 inch frac, but not consistently. Similarly sometimes the view with the 8 inch Dob can be very rewarding, but at other times only the 2 equatorial bands are obvious. I think the take home message is that to get the best out of Jupiter you have to observe it regularly, if only the clouds would allow. Try sketching. As John has pointed out, the extra time spent at the eye piece and perhaps the better concentration, does help to bring out some of the subtle details.

[michael.h.f.wilkinson]

My best views of Jupiter have been through my Celestron C8, followed at a slight distance by my old 6" F/8 "Apo-killer" Newtonian. The C8 gives more detail, the 6" more contrast at the same exit pupil. I can push magnification much further with the C8 than I ever could with the 6" Newt. My 80mm APM triplet doesn't come close to the C8 in terms of detail, even though the (tiny) image is very crisp indeed. I have looked through quite a few good refractors, ranging from 60 to 100mm, and none came close to the C8 in terms of detail. I also had a short look at Jupiter with a TEC140, but the seeing was so dismal (Jupiter just a few degrees over a hot Provence hillside), that I could not make any sensible judgement on its quality. Here are some pictures taken with the C8. The observed contrast and colour are more subdued, but with practise I can see such detail under really good conditions.

I do note that that observing planets is something requiring experience and patience. You have to wait for the fleeting moments of good seeing (and even bad nights can have them), and try to tease out the detail.