Eye pieces

[Venus88 (Amy)]

So its my second day using my telescope. I saw jupiter and i think its 4 moons. Although it was really small. So here is my question. I'm looking to but other eye pieces. But do all eye pieces fit any telescope. Also what is the lowest? I looked through a 10ml. My aperture is 150mm and my focal length is 750mm. I'm still learning. But the description when buying said I'll see jupiters cloud belt and the rings on saturn. What the best way to see these? Thanks guys!!:

[barx1963 (Malcolm)]

Hi Amy
Well done on getting Jupiter. Although planets are large they are a long way away so appear very small. Jupiter shows the largest disc of all the interesting planets, it is still fairly small. At the moment the disc is about 30 arcseconds wide. To give you an idea the full moon is about 30 arcminutes wide or 60 times larger to the eye than Jupiter. Even at opposition in March next year Jupiter will reach just under 45 arcseconds wide.
Aso at the moment it is only visible low in the west where you are looking through a lot of atmosphere and turbulence so now is not the best time to try for it. Having said that a 6" f6 scope should easily show the cloud bands and when conditions are good the Red Spot. All 4 moons should be easily visible.
Saturn is still better placed at the moment but it is getting lower late in the evening. Again the rings will be easy to see and in good conditions, Cassinis Division should be glimpsed.
With eyepieces, a 10mm in your 750mm focal length scope will give 75x (750/10 = 75) which is moderate power in a scope of this size. As to whether an eyepiece will fit your scope, that depends on the size of the focuser. Most focusers take either 1.25" or 2" eyepieces (some take 0.965" ones but they are very rare these days). Usually a 2" focuser will come with an adaptor to allow use of 1.25" eyepieces, if there is no adaptor, odds are it is only 1.25", which is often the case with smaller less expensive scopes. Or you can simply measure the diameter of the focuser tube.
If it is 1.25", any eyepiece with that size barrel will fit it.
Higher power eyepieces have shorter focal length, so a 5mm one will give you 150x (750/5 = 150) BUT remember that higher power also magnifies any atmospheric distortion and make objects move out of view quicker so think carefully before spending cash.
My usual advice to new telescope owners is to make use of low power` eyepieces first, so do you have any others apart from the 10mm?

Malcolm

[raymo]

Hi Amy, The magnification achieved with a given eyepiece is the focal length of the scope divided by the focal length of the eyepiece. Hence
750mm divided by 10mm = 75x mag. The max. mag for a given size scope is 50x per inch of aperture, so your 6"[150mm] scope would have a max of 300x mag. Sadly, these figures only really apply when the
atmosphere is unusually steady, maybe 3 or 4 times a year, depending
upon where you live. Most higher power viewing is done nearer to
30-35x mag. This would equate to about 180-210x mag. for your scope.
As mag. increases, so image quality decreases, so it can be a mistake to
buy an eyepiece giving too high a mag. A 4mm would be a good high
power choice.[187x mag.]. A 25mm would be a good low power choice.
There are two common eyepiece sizes, 1.25" diameter, and 2" diam.
Almost all modern scopes accept the former, and many have adaptors
so they can use either size. Your 10mm will almost certainly be a 1.25"
Even at 75x you should have seen two dark bands on Jupiter,
assuming that your focus was spot on.
raymo

[ab1963 (Andrew)]

Hi Amy
What scope do you have

[Venus88 (Amy)]

Thanks guys.
I have a 20mm Malcom. So I use that to find the planet then use my 10mm.
I have a 150EQ starview. Bought it off the Australian geographic Web page.
I did notice that when I tried to zoom in to much on the planet that I could see the cross section at the end of my scope. Is that normal? I'm such an amateur at the moment.

[barx1963 (Malcolm)]

Amy
So it is one of these? http://shop.australiangeographic.com...ope-150eq.html
Looks like it only has the 1.25" focuser, but if it was me I wouldn't buy any eyepieces until you know what you want.
If you are seeing the spider vanes in the image, you are actually defocusing not zooming. The only way to "zoom in" is to use a higher power eyepiece (ie: the 10mm rather than the 20mm). As a rules if the planet is as small as you can make it you are achieving focus.
Actually I will correct myself, it is possible to buy "zoom" eyepieces that can change focal lengths. Some observers love them, me I prefer stand alone eyepieces.
How is the Red Dot finder working now?

Malcolm

[Venus88 (Amy)]

Yep that is it
At this stage I'm more interested in looking at the planets. So if there was a way I could get a better view that would good. They are easier to fine art the moment. Especially with Jupiter so close to Venus.
As for the finderscope, still a piece of crap. I emailed ozhut and they said they have one that will fit my scope. The baader skysufer lll so maybe ill get that.