How can you observe Jupiter with a Dob?

[great_bear]

In my 7" Mak, Jupiter is at the limit of magnification (240x) and in terms of brightness is "just right". The surface is mottled, I can see wisps of cloud, and can see quite a lot of detail in the jagged edges if the main belts.

If I was using a bigger scope like a Dob, I wouldn't get more magnification due to atmospheric limitations. The view however would be brighter.

Since it's already as bright as need be, howcome Dob owners don't find the view too washed out?

[Beulah]

Sometimes I do, sometimes I dont.

I do find I enjoy studying Jupiter with a larger aperture. If I want to see the finer details, a filter might be applied, or view the planet when there is fine, high cloud. Apart from that, I have never had any trouble with brightness issues - just need a steadier sky!!

[todd8137]

with my 12 inch reflector Jupiter is sharp with a 8mm ep and good seing ,on the 27th nov i had to use a neoydium filter which does tease out a lot more detail and makes the grs pop the barges also seem to have more shapes ,the bands of which there is many is there as well not just the 2 main ones

[Moonshane]

I tend to use an aperture mask on my 16" dob and this reduces to 6.7" f11. This generally gives a more pleasing view than full aperture but I expect that when seeing is very good, the full aperture will rule.

I do tend to use a Neodymium filter on Jupiter which shifts the colour slightly to blue (to my eyes anyway) but you don't notice this after a short while. this filter helps bring out detail as mentioned above.

I think if you stare at brighter objects for a bit your pupil naturally regulates the brightness after a bit and this helps bring out more detail. this seems to work for me anyhow.

[mrfritz44]

Very good collimation and a moon filter works for me.

[twotter]

I sometimes use a moon filter too

[Admiral Crispy]

I sometimes use a moon filter for looking at Jupiter in my 10 inch Dob, but prefer using a yellow or blue filter to tease out more detail, particularly along the equatorial region which can be hard to see detail in (well, at least for me anyways! ) .

But most the time the brightness doesn't cause a problem because either seeing is poor, so detail is hard to see despite increased brightness of a lower magnifucation (120x), and when seeing is good I can increase magnification which reduces the brightness (240x)!

So, in short having a larger Dob doesn't cause problems, and compared to my 5" Newt it allows me to see more detail on those good nights!

[umadog]

I have to admit, I don't find Jupiter ever to be too bright. I wonder if what people describe as "too bright" is actually veiling glare (scattered out of focus light)? This may give the impression of brightness and masks detail. The "detail masking" is the problem, of course.

I was out last night with a friend--he brought his 8" Orion and I had my 18". The transparancy was awful but seeing was above average (300x night, at its best). We definitely found there to be more detail in the 18", but the Orion was definitely no slouch. The optics on those things are very good. We noticed that the brighter image in the 18" brings out the colours a lot better. We were using the same power (seeing-limited, of course) so the extra colour must simply be due to aperture since the larger exit pupil in the 18" was bringing in about four times more light.

Also, the view in the larger scope had more contrast and was sharper. There are multiple things that may underly the difference: mirror quality, aperture, and tracking. Eyepiece choice probably wasn't important since we tried several designs in the big scope an all worked well: 8mm Plossl, 10mm Radian, 7mm Nagler.

Planetary detail is a weird thing: different people say different things. What was nice about last night is that lots of people looked through the scopes and found the same thing. Incidentally, there was also a 25" next to us set up in a dome. The view through that we inferior to the 8". My suspicion is that heat rising from the dome's building destroys the views.

[Mr Spock]

I've never found Jupiter to be bright. Maybe it's a lack of contrast rather than too much brightness?

[Nitrogen]

I got in close on Jupiter last night (400x) with my 10" dob, and I was seeing it quite well. Although, I'm comparing my results to my 3.5" mak-cass. It was washed out a bit, but it was slightly cloudy (on Earth). I could see many more cloud bands than usual. A blue filter probably would have helped the contrast, but it wasn't too bright. I need to do more experimentation to find a good eyepiece combination.