Newbie Lunar Question

[Connor]

I just ordered a telescope from amazon, and it's highest mag eyepiece is 90x. Is this ok for seeing good detail on the moon? I have bought a moon filter as well. Thanks in advance

[michael.h.f.wilkinson]

You can see detail on the moon with binoculars, at 7x, so 90x is plenty. What type of scope is it?

[jgs001]

With my little 80mm, it was often better viewing at 80x than going to a higher magnification power, so yeah, I reckon 90 will be fine

[Connor]

Thanks, and Michael its a refractor

[michael.h.f.wilkinson]

Thanks, and Michael its a refractor

But which one, and in particular: what size aperture?

[Connor]

Well it's a Celestron Astromaster 70AZ with 70mm aperture (I'm pretty sure you commented on my other thread where I talked about it)

[michael.h.f.wilkinson]

Well it's a Celestron Astromaster 70AZ with 70mm aperture (I'm pretty sure you commented on my other thread where I talked about it)

Quite likely, but I natter so much online it is hard to remember it all .

Your 70mm should show plenty of detail at 90x. On good nights you could push to 120x, but beyond that, you will need more aperture to get away with that much magnification. Plenty to see on the moon at that magnification.

[Laowei Tony]

Question: If viewing the moon through a 70mm refractor (as Connor has) or something slightly larger could you use a higher magnification as the moon is rather bright?

[onesmallstep]

Hi

Regarding magnification, the rule of thumb is 2x mag per mm of aperture so a 70mm refractor will give a maximum practical magnification of 140x. In reality there are a number of other factors affecting mag including air quality, sky conditions (thin cloud, light pollution, etc), viewing location, an individual's eyesight, and scope / eyepiece quality. Considering these factors a more practical level of magnification is 1x - 1.5x mag per mm. This isn't as bad as it sounds as at 15x the moon will fill an eyepiece fov and at 70x you will be observing individual lunar regions. Planets will also look good under these mag levels and what you lose in all-out magnification you will make up with smaller, crisper images. DSOs are the opposite as most respond well to lower, widefield mags.

Overmagnifying leads to loss of detail as you go beyond the focal length of the scope and magnify the air between yourself and the object being observed. Another effect of overmagnifying an image is you also magnify the effect of the Earth's rotation so the image will pass through your ep / fov too fast for any real detail to be picked up (unless you have a driven mount, of course).

HTH!

[Alkaid]

Your 70mm frac will show you the major craters (eg. Copernicus, Tyco, Clavius, Plato plus many more), the mountains and mares, plus some other geological features such as Schroter Valley, Alpine Valley, and perhaps even the Straight Wall (lunar fault) under the right illumination.

Good luck and have fun!

[Matt Scunthorpe]

You'll never get tired of looking at the Moon in any size scope. It has so much to give and is generally taken for granted.

[Adrian lord]

Agree with Matt - an overlooked target that is even rather detested by Deep Sky devotees, but has fabulous challenges and landscapes to explore.

I have always wanted to spot the central rille running the lenght of the Valles Alpes - but no luck so far!

[nightfisher]

You'll never get tired of looking at the Moon in any size scope. It has so much to give and is generally taken for granted.

Yep, after all these years i still love viewing the Luna surface