Planetary Viewing

[ApprenticeAstronomer]

Hi all,

I am new to observing and have been trying to view Mars, as it was easy enough to find. When looking through my scope it looks like a bright star through the eye piece. Maybe am being stupid but shouldnt I be seeing an image somewhat spherical and planet like Am using a Skywatcher explorer 130m with a 25mm wide angled eyepiece.

Your help would be greatly appreciated.

[richbyers]

25 with your scope is a bit too little magnification to give a disc- with my 130 i need to use at least a 10mm

[ApprenticeAstronomer]

Would a 10mm lens with a 2X Barlow be of any use?

[Atlas]

Yes, but it may be too much mag for the scope with the combo, try it and see. Should be ok.

[JamesM]

Your scope has a focal length of 900mm which when divided by the the focal length of the eyepiece (25mm) will give a figure of 35, the magnification. Therefore, a 10mm eyepiece will generate x90 magnification which is clearly a significant increase. Now a 10mm with a x2 Barlow will have the effect of turning that eyepiece that a focal length of 5mm, which when applied to the focal length of the scope (900mm) gives us x180 magnification. As you magnify the light that your scope's aperture can capture, what you are actually doing is stretching the light, which has the effect of darkening the final view. Mars is a smaller and darker planet compared to Saturn and Jupiter and although the image at x180 will be larger than with the other eyepieces, I'm not sure how much detail you will be able to see. You should be able to see the polar region but there is also the the effect current seeing conditions along with the fact Mars is receding from us that will also impact the view. Magnifications of x180 to x200 are about the limit of what most of us can normally use in our night skies, and so using your Barlow and the 10mm will get you closer, but I have no experience of how well this particular Barlow performs. A Barlow by TAL (Russian) is modestly priced and is a good performer and might be worth a look at in the future.

Clear skies

James

[Si Rollett]

I take its to far away for low power scopes,I had a go to look at mars with my 10mm eye, after viewing Venus so if I was to push my scope with a 6mm ep which is 150x I think, I might be able to tell its a planet? What do you think about a 8mm which is 112x my scopes aperture is 70mm?

[brantuk]

We were viewing both saturn and mars tonight at 430mm fl with a 5mm eyepiece giving 86x mag. Saturn was clear as a bell with the rings visible and the shadow of the rings on the planets surface. Mars was crystal too and seen as a bright and perfect sphere with a hint of blue at the pole and an overall reddish tinge fading in and out with the seeing.

But the transparency was too poor for detail and whispy clouds gave clarity for only a few seconds at a time. Your scope should be fine at 900mm with a 10mm eyepiece and 90x magnification - any higher though and it would begin to go grainy and faint

[umadog]

It's not just that too much power makes the image dimmer, although that's obviously important. A couple of other things matter also. Firstly, the view becomes dim because the exit pupil becomes small. A small exit pupil means that the floaters in your eye start to show and that's annoying. Secondly, the resolution a telescope is capable of generating depends upon the size of the size of the objective. If you over-magnify then you just start to magnify blur caused by diffraction of light as it passes through the objective. Telescopes over about 8" will usually be limited by the atmosphere, not the instrument's potential resolution. On the steadiest nights, a 6" will start to become limited by the optics rather than the skies. Smaller telescopes will tend to be limited by the optics. For example, the 70 mm mentioned by Si will be be at 41x per inch at 112x. That's probably too much power (Useful Magnification Ranges for Visual Observimg - How To). In practice, about 80x is the most you'd want to push with a 70 mm. Then again, you should try it for yourself and see how it looks. Note that as you push to these very high power per inch numbers, the quality of the optics become progressively more important.

[Si Rollett]

Well this isn't going to be the only scope I will buy so Buying new ep won't be a waste if it doesn't work well This I will have them for the next one

[gfletcher]

Mars is a particularly difficult planet at some times.

Be patient because every now and then you will get moments of clarity.

These moments may only last a few seconds but patience is the key.

Graham

[ApprenticeAstronomer]

Hi all,

I managed to view Mars and Venus tonight for the first time. I could make out the planet like spheres, however I could not make out any detail. I used 10mm MA and 2X Barlow. I think ill order myself a 6mm Plossls eyepiece and see what I can get. A very happy beginner tonight

[dav1d]

As another user mentioned to me on a different thread:

Mars is *fun* isn't it Dav1d.