10" Dob Planetary Advice

[Koje]

Last night I was pinging between M42 and Jupiter, both fantastic.

M42 was looking good in the 32mm wide however Jupiter although sharp though my 8.8mm wide (x136) I could only just make out the red spot and the whole planet was without colour (banding was ok and moons sharp).

This is the first time I have seen Jupiter in what I would call a proper clear crisp night.

I spent my time with it and the atmosphere was at times very clear however no colour. I did give the scope a knock on the garden hose reel so collimation may not have been spot on but stars were fine and the moon was crisp when setting up. Maybe I need to check collimation and/or go down to more magnification i.e 5mm?

What do you think?

[ronin]

You could simply have so much light collection that the darker bands were washed out by the overall light from Jupiter.

You would have to drop in a shorter eyepiece to check, have you a 6mm as well as a 5mm?

You will find that 1mm can make a difference.

So now you have:-

1) Excuse to go observing again - need to check if a shorter eyepiece improves Jupiter.

2) A reason for another eyepiece if no 6mm available to you.

See there is always a positive aspect to this.

Also the GRS is not all that red, murky palish orangy brown may be closer.

Bit like galaxies, they are not really glowing pink/red in the arms when you actually see one in a scope.

[Koje]

I like your thinking....

However 8.8mm is my shortest eyepiece hence the question. Good point on the too much light angle. Perhaps a filter may be the best option.

Still a 5mm or 6mm may be on the cards....or a good quality barlow.

My 14mm was washed out also so like you say maybe too much light on suck a clear night.

[Reeny]

5mm might be too much

My best, sharpest viewing on Jupiter is at 165x with the 16mm Maxvision in a 2.2x Barlow.

However - last night the viewing was exceptional , and I was seeing good detail with the 6mm Delos at 200x

240x magnification sometimes works on Jupiter, but last night 200x was the max (even thouggh the moon took 300x)

The thinking around here is that 170-180x mag is best for Jupiter.

My vote would go with the 6.7mm Explore Scientific 82 degree = 180x mag

£98 plus postage http://www.365astronomy.com/Explore-Scientific-Eyepieces/

[Northern Soul man]

Hi Ya Koje, congrats on the scope - nice1.  Jupiter is probably the best Planet detail wise, but you really have to work at it - 1 word comes to mind - Patience.  I've spent hours watching and looking, colours to the human eye are very hard to spot in planetary detail, just usually different tones of grey are what we all see, more so in the DSO's - just a different shade of grey - I think the best scopes for Planetary are the very long focal length ones above say around F10, but there is a lot to take in and there are a lot of factors that need to be just right to get the best out of our scopes, the main one being the seeing - I was out last night with my CPC 1100 (bare in mind I've been Jupiter watching for many years now!!) and at F10 - it looked very nice with colour in the bands - even the GRS was a distinct orangey reddy colour, a large number of white ovals, 2 moon shadow transits - all in the space of a few hours.

You need to really just LOOK - nothing else - just LOOK - the more time you spend looking, the colour and detail - all be it very faint and NOT at all easy to pick out, starts to reveal itself, varying greatly as the conditions change from different shades of browns in the bands - to really bright whites in the Ovals, even the hollow where the GRS sits is very bright at times, more distinct that the Red Spot itself at times.

Its just down to practice, getting the conditions right and above all the seeing plays the major factor in it all, some nights (like last nigth) were very good, but most of the time it becomes VERY difficult to tease out very faint detail.

Paul.

[Reeny]

My 14mm was washed out also so like you say maybe too much light on suck a clear night.

I use filters for the moon and Jupiter - but if I am in a hurry, I can easily stop down the apperture by re-fitting the dust cover lid on the end of the tube, and removing the small 2" cap.

Bingo.

[Moonshane]

with most scopes when you first look at Jupiter you see nothing but a white ball. within a minute or so, the main bands, moon shadow transits and polar caps become obvious, after maybe 10 minutes the GRS and some further banding detail becomes visible and eventually the full possible detail given aperture, seeing and magnification will be visible. you do as above have to be patient and work at it.

[Koje]

Thanks for all the good info. Perhaps I was expecting too much, it was such a good night I was hoping to get some colour. Next time I will stick with Jupiter for longer to tease more detail out.

I will still look into at shorter eyepiece although it may be tricky keeping it in view, gota love a Dob 

[Qualia]

Koje,

Good seeing conditions override problems with LP, and assuming collimation is spot on, you'll find that on average Jupiter doesn't need much more than between 120x - 180x to get some cracking views. If seeing is below average, you'll still be able to tweak out a reasonable amount of detail at 90x to 125x.

A small 3" frac can easily make out the north and south equatorial belts, great red spot, the equatorial band and the north and south polar regions. If you stick with him, gradually, after 15 minutes or so, Jupiter reveals even more subtler markings especially in the north and south temperate belts and larger markings in the north and south tropical zones. Of course, a 10" will offer a whole new experience of resolution but generally speaking, the entire image of Jupiter in the eyepiece won't be much bigger than a large pea in the palm of your hand.

Try to view Jupiter close to the zenith or celestial meridian and you'll probably find that on an average night your sweet spot is between 120x to 170x. You've got a lovely scope reaching out across the universe some 675,000,000 kilometers and assuming the colimation is spot on, I'm sure with a little practice you will be able to see the Great Red Spot, those delicate reddish-brown belts, a darker, greyer hue to the Polar regions, and so on. You'll be able to trace the movement of the Jovian moons and observe their play of shadows over Jupiter in times of transit or of their eclipses by Jupiter's own shadow.

If you can, try to sit with Jupiter for a peaceful thirty minutes or so on your next observation session, ask yourself questions about what you are seeing, perhaps make a little sketch which will train the eye to see more.

Good luck and let us know how you get along.

[jetstream]

Sometimes when the sky appears very clear the seeing can be very poor and it happens to me a lot. This will wash colors out even if the sky is stable. It isn't like this all the time though- last night was very clear and Jupiter took a solid 240x with 300x being sharp for brief seconds. Having at least one "warm" tone eyepiece of reasonable mag (150x) can really help out with the colors, as does proper collimation. The views are always best in the center of the FOV  in my dob (like yours) as this small zone is the coma free area.

I use the moon to check seeing.... the terminator took well over 300x sharp, so I knew Jupiter would be VG once it rose.HTH, Gerry

[Northern Soul man]

Great advice from above, last night was very good here in the Midlands - well my back garden anyway!! - I stuck with the 12mm EP last night giving x233 in the 1100, this was just about the limit for the seeing conditions - a very nice disk with an absolute wealth of detail, i just tried Barlowing a 17.3 giving around x325 (from an effective 8.5mm EP) - yes the detail was there but you really had to look for it under moments of better seeing - it just didn't stand out so much, but I always find that the image at this power is very soft - nothing like the 12mm - even the 24mm (x116) was very nice and much preferred the lower powers, even though the seeing was good there were times when it just broke down, but as mentioned above by Qualia - you really have to question what your seeing, the eye can pick out very fine detail from such a small disk, I tend just to keep moving around the disk - not so as to stick in 1 place for a long time, remember fine detail, such as  and make a mental note of where they are in relation to say the GRS, or a storm splitting a belt - or in relation to a shadow transit, like last night in the North Equatorial belt, as time goes by, more belts in the temperate zones start to show - these are nothing like the intensity of the Equatorial region - just very fine slithers as the seeing steadies - even down to the white ovals in this region - the more you concentrate, the more detail shows - over an hour or 2, you can make a very detailed image in your head of whats up there - last night was special though so many phenomena, occultations, shadow transits, GRS transit - all in the space of a few hours. Fantastic!!

Paul.