Jupiter - with new 250px Dob

[DrNeb]

Hi All,

first off, Merry christmas!

Basically, i just have a quick question that i would like to ask.

I set up my new dob last night, sat it outside to cool for an hour and set my sights on Jupiter. (i should mention, i have quite a bit of light pollution in my back garden with all the street lights but the sky was very clear)

I found the skywatcher standard finder scope very easy to manage, if not a little hard on the neck, but i soon got jupiter in my sights.

I tried using both of the standard lenses that shipped with it, the 24 and the 10. the views were fantastic! well, at least a lot better then i've seen in my old 3 inch!

However! the glare was overpowering the views, i could make out the thick band but not much else, the detail would fade in and out like someone was using a dimmer switch.

I put a variable moon filter which managed to help slightly, but it seemed to detract from the experience, the moons would disappear completely and the detail would only be slightly better. the glare still shining through!

Any tips or tricks to aid me?

perhaps I need some better eye pieces?

I would appreciate any thoughts on the matter.

[dweller25]

I have the same scope and use a 50% ND filter to reduce the glare with a 6mm Radian at x200. It seems to give a good balance in terms of resolution and detail.

[Rob]

As Davids already said here.. you have to tame the brightness as Jupiter is real bright target. I find that I can get away with it as using a 6 layer EP in a barlow. Lots of lenses cut the brightness down.

You could also try a cheap LPR filter, that would also help the LP problem?

Cheers

Rob

[John]

My tip is to keep observing Jupiter, and other objects - spend chunks of time on them. After a while your eyes adjust and gradually you can tease out more and more details. If possible I try and spend at least an hour and often 2-3 hours on the one object. Towards the end of such a session I'm picking out far more subtle detail that I did at the outset. Yes, the detail coms and goes with the good patches sometimes lasting only a second or two but, if you give your eye a chance, if will "tune" itself in and hold onto the subtle details as they come and go.

It's easy to get impatient and move onto to something else but, in my expereinece, the rewards come for those who can put the time in.

[Neil English]

My tip is to keep observing Jupiter, and other objects - spend chunks of time on them. After a while your eyes adjust and gradually you can tease out more and more details. If possible I try and spend at least an hour and often 2-3 hours on the one object. Towards the end of such a session I'm picking out far more subtle detail that I did at the outset. Yes, the detail coms and goes with the good patches sometimes lasting only a second or two but, if you give your eye a chance, if will "tune" itself in and hold onto the subtle details as they come and go.

It's easy to get impatient and move onto to something else but, in my expereinece, the rewards come for those who can put the time in.

Sound advice if ever I've heard it. Big Dobs like these are sensational tools for divining fine details on the large gas giants. Patience is the watchword, but when conditions are right they deliver killer views of our planetary neighbours. This year, Jupiter hasn't been especially well placed, but next year promises far more favourable conditions for us northern Europeans. With a 10 or 12" Dob, you'll get views that resemble the old Voyager photos when conditions are good. Here's looking forward to 2011!

Cheers,

Neil.

[Starblazer]

Try reducing the aperture by putting the cover on and removing the little hold covers.

This should reduce the amount of light gathered and hopefully give you a better view with less glare.

I'm not to sure it's wise to stare at a bright glaring object at high magnification. Kinda like staring at a lightbulb for a long time, it will eventually make your eye's less sensitive to light and possibly irreversibly.

[DrNeb]

thanks all!

starblazer, too true, the moon filter seemed to help with that!

i spent about 2 hours with jupiter last night, the seeing was much better then my previous attempt and i managed to make out quite a lot of detail.

I will indeed try keeping the dust cap on and removing the small cap. (not sure if this was correct but that is how i have been cooling my scope, didn't want to leave the whole cap off just in case, maybe this is wrong...

I appreciate all your wise words! god knows i need all the help i can get ;o).

[John]

Try reducing the aperture by putting the cover on and removing the little hold covers.

This should reduce the amount of light gathered and hopefully give you a better view with less glare...

Only problem with this is that is restricts the effective aperture to that of the small holes !. I Can't see the point of owning a 10" scope then reducing it's aperture (and resolution, contrast etc) to that of a much smaller scope myself

[Moonshane]

I agree John

I think if, as you say, you look at (bright) Jupiter for a longer period, the detail gets better and better the longer you look. I suspect this is contraction of the pupil allowing more depth of field in the eye (like a camera) but am never sure if this is right.

[Moonshane]

I'm not to sure it's wise to stare at a bright glaring object at high magnification. Kinda like staring at a lightbulb for a long time, it will eventually make your eye's less sensitive to light and possibly irreversibly.

I don't agree with this Starblazer. To my knowledge it's not possible to damage your eyes with Jupiter or even the moon (I don't generally filter the moon even with my 12" dob) as you cannot make it brighter than it is with the naked eye. Granted you won't be watching any faint fuzzies for a while afterwards but of the moon's out anyway......The sun is obviously a different kettle of fish. I think the difference is reflected light or emitted light? Higher magnification would actually reduce the effect compared with lower magnification.

I do find that my Baader Neodymium filter reduces the brightness of Jupiter and emphasis detail so this might be worth a try.

[DrNeb]

well i'm not sure if it's because im just not used to it, or if starblazer is right, I've got a killer headache! it started literallly an hour or two after viewing jupiter for such a long period of time. however.... it could just be all that Christmas bubbly lol. i'll try out a view more settings on the moon filter.

i just wish this moon filter had like a stop click method of adjusting it... it is quite a pain in the bottom, but i suppose it will all come with practice.

[Lux1]

I have a 5" reflector so very small compared to the big monster dobs, however after observing Jupiter for a while I can see several cloud bands and different colouration around the poles. I have even seen the Great Red Spot for a few seconds in excellent seeing. Just keep at it. In a month or so Jupiter just won't be worth bothering with as it will be so low down on the horizon.

On another note I saw a cheap 50mm retractor in a supermarket the other day, it had glorious images of Mars, Saturn and Jupiter on the box as well as several DSO's. Talk about misleading. How many kids will that disappoint this Christmas. It will only be good for the moon at a push.

[Ags]

I find that 150x mag works well in my 102mm aperture scope - a reasonable image size and bright without glaring. To get the same surface brightness in the image in a 250mm scope would require a magninification of around 375x - too high for the seeing probably, so I guess you need to use a filter of some sort.

[Nexus 6]

My tip is to keep observing Jupiter, and other objects - spend chunks of time on them.

have to agree with that john, spent a lot of time on Saturn last year and had some excellent views of it, once you are committed to spending an hour or so on the one subject and you have reasonable conditions and wait to get it at its highest position then its totally worth it.

Alan

[DrNeb]

I have been spending chunks of time, but the glare was giving me such a headache! as soon as i get another clear night i'll play around with my moon filter a bit more.

Also, i'll pick up a x2 barlow and stack it on my 24mm and give that a try. the stock 24 is supposed to be the better eye piece in the standard set.

the next clear night i think i'll aim for a dark site too.

Cheers all.

[Starblazer]

The 250px grabs a **** load of light mate, the moon is a definite no no without a filter on this. As I said earlier, I know some disagree, but using filters to help contrast is much better than abusing your eye's, especially if dark adapted only to put it in front of an eyepiece with a glarey ball. Barlow's do drop the brightness down a little and up the size, so that is definitely an option.

For the others...It's ok to say it does not damage and hasn't hurt you, not everyone's eye's are the same.

[brantuk]

It's all common sense really. If you have a headache and your eyes are over sensitive then just don't look at bright objects - whether alcohol induced or otherwise lol.

Using the dust cap method is fine for a short term fix, but a filter in the long run will make your viewing more productive if your eyes are more sensitive than normal.

The main reason to go large on aperture is to gather faint light from distant objects, but anything in the solar system is closer and will be much brighter - so choose your ep's and filters to suit you - it's a personal thing really

[mdstuart]

I would say after a few years of experience the "seeing" makes a big difference. On many nights the sky wobble makes picking out detail very tough. Like looking at a newspaper at the bottom of a swimming pool and trying to read it.

Then just on about two nights a year the sky settles and WOW its so sharp with all the detail. The water is calm to use the swimming pool analogy...

Mark

[DrNeb]

would a colour filter help at all? wish i could get out and try my moon filter on a different setting, according to the bbc weather its going to be cloudy for the rest of the week.

Very annoying >.<

[xboxdevil]

Before you buy any filters I would try the view with a dew shield in place, the secondary mirror is probably getting a lot of scattered light.

[DrNeb]

I'll be picking one of those up with the next pay cheque i reckon.

jupiter was quite wobbly the first night, but it was noticeably better the second night.

I also managed to see the orion nebula, i was astonished at how much nebulosity i could see without any enhancing filters in a light polluted area!

I will report back as soon as i get some clear sky.

Cheers all! - feel free to keep adding your "two cents". As i need all the help i can get.

[DrNeb]

removed - move to new thread.