Great brief Jupiter
Posted 19 November 2012 - 12:50 AM
The short of it was this: with my fan sucking in.cold air from the secondary end it soon fogged over with dew. If that weren't enough the seeing deteriorated into flairing moosh. I hung in there and tried to refocus past the dew and seeing (I was desperate) but ofcourse its a losing battle. Anyway here's the Jovian eye candy I gleaned...
1. Brightest value is the light streak seperating the neb from the ntb. In those good moments at 173x and 200x it really popped clean and bright.
2. The moon shadow was exquisite. Its never ink black assome describe it but man it was sharp!
3. When the moon casting the shadow began contact for transit it looked like Jupiter grew a bump. The vanishing small night sky between moon and limb of Jupiter provided for a truly crisp presentation
4. The Neb was terrifically split with a prominent though subtle festoon angled out of its preceding side of the cm. Lots of irregularities in both belts.
5. South polar region looked distinctly two toned as opposed to a general gradient.
6. At 450x Ganymede is wonderfully fat but seeing degraded miserably as mentioned.
7. The ez was swathed in undulating intensities of festoon wash tho only but one festoon showed strong.
Equipment note: The red enhancing Mars Filter by Orion which is abysmal with my 6" act due to horrible violet color fringing fared far better with my reflector. The red in the belts truly fired up. Was it beneficial? It was fun. Unnatural but wild to see the belts saturate in red.
Daniel Mounsey did a great write up on planetary eyepieces in which he mentions UO Abbes having clarity but bothersome color fringing. This had always been evident with my refractor. In my reflector these UO orthos are terrifically colorless like my plossls. A cooler tone but no fringing. I woñder if its peculiar just to refractors. It was a relief to see it localized to a scope design.
Anyway sketch coming soon from my 70mm ob last night. I was to frustrated to draw besides defeated this evening. Briefly it was a beautiful thing.
Posted 19 November 2012 - 04:52 AM
The EZ does seem to be a hive of activity this fly by. Last year seemed rather rather tame. The poles are less active, it seems, the SPR looks different depending on the CM.
You know, I guess your fan works too good. Man, if it's causing your mirror to cool very quickly to below the dew point...is that possible? Hmmm...
Posted 19 November 2012 - 07:26 AM
. It was even sucking my hand thermals in I could see it in the defocused image. I wasn't at all happy with the fans. I'm turning the rear fan so it blows on the primary and I've got to do something to increase boundary layer flow.
At anyrate it was good...stunning even but as mentioned when the trap shows neither e or f its turned awful.
I'm posting my problems in the reflector forum
Posted 19 November 2012 - 07:49 AM
Christ, Pete, you have one of those swamp air boat blades drawing air down your tube?
Seriously, I guess it can be a concern. Never would have imagined it, though. I always thought the idea of helping hot air rise out of the tube would be best, help it do what it wants to do. And, yea, you can get cooler air from below the mirror, I guess.
Dobs are works in progress, aren't they? Mine was, this or that mod. But, it's a nice platform for that killer mirror you have.
Anyway, at least you got to see what some of have been ranting about. Jupiter is just taking my breath away, nightly. (Speaking of that, I hold my breath when my face is near the meniscus.)
Posted 19 November 2012 - 07:54 AM
Posted 19 November 2012 - 08:06 AM
Seeing here is weird, still trying to understand it. Walk outside and the stars twinkle pretty good. Put a 6" aperture on it and it's dead calm, besides some atmospheric dispersion. In fact, I use it to kind of time the moments of best seeing. Really buckle down when the red fringe begins to fade.
Posted 20 November 2012 - 11:08 PM
I'm not sure if this will help with your fan arrangement but I use a dew shield on my scope that prevents my secondary from dewing. Before the dew shield I had a few nights where dewing on the secondary shut down my observing even with my fan blowing on the back of the primary.
I made a dew shield out of a foam mat that I spray painted black. It extends over a foot past the end of the tube. Haven't had a problem with due since.
Sounds like you were getting a great view of Jupiter though and hope you have plenty more as it comes to opposition.
Posted 21 November 2012 - 06:22 PM
Ill tell you with the air blowing the other way this hasn't happened yet but my fan thing is still a new thing I'm working it out. I'm guessing though since your tube is 12" wide and mine is ten you may have a little more issue there? I'm reaching here LOL. The view was a beauty for a good 15 minutes then got ...well you know. I wad psyched tho ... you know that etched look of the details fluttering g in and out. Anyway its cleeeaarrr tonight so round 11 the scope goes outside and fan a humming! My tube by the way has another set of mounting screw holes farther up the so the primary can reach focus for cameras. Imaging etc. I might use these to get better boundary wash.
Anyway look purty out there now with no atmospheric spherical aberration haze at 18'000 feet