# Amateur observing

I'm new to this could someone tell me if I'd be able to see planets with the Celestron Cometron FirstScope described as below on argos.co.uk:

A compact, easy to use and powerful 76mm reflector telescope which will give fantastic views of the Moon and stars. The Dobsonian mount design is best used on a table or window ledge. The included eyepieces allow for 30x and 15x magnification. The included finderscope makes locating objects a snap! No tools are required to assemble.

• Optimum magnification 30x.
• Maximum magnification 30x.
• Portable design perfect for use in the garden, from a window ledge or camping.
• Two eyepieces included for 15x & 30x magnification.
• Weight 1.95kg.
• Size H39.4, W24.1, D23.8cm.
• Manufacturer's 2 year guarantee.
• Please do not post pictures with text on SE sites, that is not searchable. Edit the text into the question. Also: where do you live; what are the sky conditions (light, dust, weather). – user1569 Sep 24 '18 at 11:54

For your telescope I'm reading different statistics on Celestron's website than the ones you posted in your question:

Highest Useful Magnification 180x
Lowest Useful Magnification 11x


I'm new to this. Could someone tell me if I'd be able to see planets with the Celestron Cometron FirstScope?

You can see the planets with your eyes in a clear sky (even with some light pollution). They look like colorful stars that don't twinkle. In a telescope of low magnification and poor build quality you can also see the planets: they just look like bigger disks of light without recognizable details. The question you're not asking is "What do I need in order to see the details of the planets?" or "What do I need in order to get spectacular views of the planets?". I'm including an excellent answer to this follow-up question from a separate post to this site:

As a general rule, there isn't much point in pushing the magnification above 2x the diameter of the instrument, measured in mm. 3 inch, that's 75mm, that's 150x max. Beyond that limit, even under ideal skies the image is large but blurry.

After that, seeing (or air turbulence) pushes that limit further down. Your aperture is small enough that it almost never suffers from seeing, but larger instruments are often affected. It varies greatly with time, place and season. There are times when a 12" dobsonian, that in theory could do 600x, is clamped down by seeing to 150 ... 180x. There are times when you could take a 20" dobsonian all the way up to 1000x - but that's very, VERY rare, it's the stuff of legends.

Assuming average seeing conditions and instruments of usual size (refractors of 3...4" aperture, reflectors 6" or larger), here are some rules of thumb:

Jupiter is seen best under mid-high magnification. It's rare that more than 200x is beneficial. This is because it's a very low contrast object, and additional magnification comes at the cost of less contrast, which makes things worse.

Saturn works best at high-ish magnification, bit more than Jupiter but maybe not much more. Around 200 ... 250x usually works. It depends on what you do - if you're trying to see the ring divisions, push it a bit higher.

Mars can use the highest magnification that you could generate, given the instrument and the conditions. It's a very small object, contrast is not bad, so crank it all the way up. Most instruments are limited by seeing when observing Mars.

Moon is the same as Mars.

As you can see, magnification is never an issue for you. More magnification will not make it better. In fact, more magnification always means the image is more blurry, not more crisp - it's always a compromise between size and blurriness that decides the optimal magnification.

Assuming this reasoning is correct in your case, it looks like you'd be able to see Jupiter with this telescope in some detail, but perhaps not the other planets with any helpful level of detail.

As a side note, I'd strongly recommend replacing those Kellner eyepieces with something better (Plossls or better). And quite frankly, if planetary viewing is your passion, I'd look into saving for a refracting telescope and eyepieces of high quality rather than a budget starter kit.

Visually without a telescope or binoculars you should be able to see Venus, Mars, Jupiter and Saturn, even in most light polluted cites.(Possibly Mercury). So with the telescope you describe you should be able to see some planets, the Moon, stars, etc. The rings of Saturn and the Galilean moons of Jupiter and Lunar details should also be visible. Planetary details will probably not be visible because of the small light gathering ability of the telescope.

• With that telescope you may be able to pick out light and dark bands on Jupiter. I am trying to remember the smallest one that I managed it with as it must be about that. – Rory Alsop Sep 24 '18 at 19:59