View Full Version here: : Planetary images too bright, help required!
18-08-2006, 10:52 AM
I've just recently puchased a Celestron 127 Powerseeker scope (my first scope), this is just to tie me over until I can afford the "Good Stuff" and I'm having trouble with viewing Jupiter. I can see the moons okay, but Jupiter is just too damn bright! I cannot see any banding even if I use 20mm by itself, add the barlow, switch to the 4mm by itself, barlow is not used on 4mm. Stars seem okay, Moon... WOW! Joops just seems like another star.
The scope is standard out-of-the-box, no extra accessories have been purchased yet. It came with 20mm & 4mm eyepieces & a 3x barlow. No filters at the moment.
Please help me!
Thanks in advanced!
18-08-2006, 10:57 AM
A couple of quick questions. Did your scope come with a plastic cover to go over the end to prevent dust getting inside when storing the scope. And if it did, does it have a couple of removable small circular covers as part of the big one (I hope this sounds sensible :P )
If that is a yes to both questions, then put the cover on and remove one or both of the small covers. That will reduce the amount of light getting in and hopefully improve your contrast.
18-08-2006, 11:00 AM
Hi, :welcome: to the forum!
Is the Celestron 127 a reflector or refractor? What is it mounted on? I guess 127mm is the size of the objective? What's that, 5"? It must be a 5" reflector then?
Have you checked collimation? What time of night did you view it? How high above the horizon was it?
You're really missing something like a 10mm eyepiece for that scope - the 20mm is a low magnification. Jupiter's disc would be quite small, but if it's well focused and collimated, you should still be able to see the 2 main belts. If it's too bright, you could try a filter or try increasing the magnification.
Unfortunately with the 3x barlow (likely to be of questionable quality), when used with the 20mm, it gives you approx 6.5mm eyepiece, which is probably too high power for this scope, especially if the seeing conditions aren't very good (which they haven't been, lately) and if the scope is not well collimated.
Something around a 10mm eyepiece (if you had a 2x barlow) would be better, as the higher magnification would make it appear less bright, and hopefully the 2 brown belts would stand out a bit clearer.
To get you by, you could get a cheap 2x GSO barlow from somewhere like Bintel or Andrews. The 4mm is pretty much junk, you may as well throw it away as the likelihood of it a) being good quality, and b) seeing being good enough to use it, is extremely unlikely.
Hope that helps.
18-08-2006, 11:23 AM
Thanks 1Ponders, it does have a dust cover with one removeable cap. I'll try it out.
Iceman - Thank you! It's a 5" reflector on an EQ2 mount. I understand that this scope is of questionable quality, but atleast my foot is in the door. I've been warned about the 4mm eyepiece and hardly use it at all. Collmination has been checked and seems fine. I normally set the scope up as the sun disappears and I check Joops regularly until about 12am-ish. I mainly see it after Zenith and just before it disappears behind some hills. I'll look into getting a 10mm with 2x Barlow. At the moment I'm a budget hobbyist until funding improves, then the real fun starts.
Thanks heaps! :thumbsup:
18-08-2006, 11:58 AM
How did you check collimation and how long ago?
The scope has a 1000mm focal length, and from photos it looks like the tube is quite short, so it might have a barlow lens in the focuser. Does it?
10mm or 12mm eyepiece would be good for a closer look at Jupiter in that scope. If the scope is half decent and well collimated you should be able to see the two main cloud belts on Jupiter even in poor seeing. GRS in good seeing (when facing us).
18-08-2006, 12:16 PM
Welcome to the forum :)
Your scope is more than capable of viewing Jupiter, just don't expect to see Hubble type images.
A few points:
With 5" aperture the maximum magnification on a really GOOD night will be 250x which is what your 4mm gives.
I would bet that the 4mm is not a great eyepiece so you can use it as a paper weight.
You can also bet your 3x barlow is not great, another paper weight.
So what to do?
Your 20mm (50x) will perform quite well as low powers are much more forgiving to quality so its a keeper.
Get a good 2x barlow like an Orion Shorty Plus - good investment and can be used with future scopes.
Get two other plossls - 15mm (66x) and 12.5mm (80x)
These can be doubled up with the barlow to give you a range that can be used on most nights.
I know this sounds like a lot of money but for starters GS eyepieces and barlow will work quite well and show a marked improvement.
How to use:
Put scope out for an hour before planning to use it.
Observe on a grassy area to help stop thermal interferring with your views.
Most nights your scope will work best below 125x so the 15mm and barlow will be your workhorses.
Going up in power will not improve your view if the previous power is not crisp. Better to back off to the next power down, a small crisp view is way better than a large blurry one.
Enough preaching, hang in there, Jupiter is not as easy to observe as you would expect but you should turn up the equatorial bands. Saturn will really hook you and you should get some great views of Omega Centurii and 47 Tuc.
Keep looking up.
well the questions are answered so i'll just say welcome aboard :)
18-08-2006, 04:39 PM
My sentiments exactly Olly!!!:P :lol: :lol:
18-08-2006, 10:30 PM
There are two filters that I would try to reduce the brightness:
A ND0.9 - A Neutral Density 0.9 filter, often sold also as a moon filter. Doesn't affect the colour, only the brightness.
A yellow filter is also very good for Jupiter, either a #7 or #8 (now , have I got those numbers right...?) The #8 is the more common one, the lighter yellow usually only comes in sets.
18-08-2006, 10:33 PM
You definitely don't need to reduce the brightness of Jupiter in a 5" scope (or even in a much larger one for that matter). It will only reduce the amount of detail you will be able to see.
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