Large Medium Small what is the actual size?

[Sirius Starwatcher]

So As a newbie I am reading avidly anything I can get hold off. At the moment it's astronomy now mag. I keep reading references to a small telescope or a large telescope. Is there an actual definition, reference the size of scope?. What size aperture does a small scope become a medium scope ?

Thank you for all replies.

[Charic]

 For now I assume anything less than 6" is small, 8" to 12" as Medium and above 12" as large. 

Similar with focal ratios,  is there a  decisive cut-off between fast, slow, medium? 

We learn something everyday!

[coulthamst]

It depends on who is talking, but usually refers to aperture. For instance, up to 100mm could be regarded as "small", up to 250mm as "medium", anything bigger as "large". Others may pick different size ranges, but the princiiple will remain the same.

(Edit) Crossed with Charic, but singing from the same hymn sheet!

[damnut]

Hi Garry,

As above if you are talking mirrors but,   if you refer to refractors ,  60mm small,  120mm med , anything bigger than 150mm large. I have a 152mm frac and that is as big as I would want one, but had a 250mm sct and could have handled a 300-350mm  on my own...

[Davey-T]

Depends if your talking optically or physically, a 60mm f/15 refractor may be somewhat larger than a 100mm f/5

Dave

[Sirius Starwatcher]

So, interesting replies to the question I posed based on the articles in mags etc. This indicates to me that some of the written articles are giving loose information as opposed to accurate info, which does not help a new person to the hobby.

[damnut]

Hi Garry,

Its a bit of a personal one , the two pics below is my kit as now. The 152mm frac is the most difficult to mount (  I am 6'3 and brick outhouse!), the drop down to 120mm in apperture is amazing, the main pier has 152mm, 120 mm short and a 150mm Mak. The tripod has 127 & 120mm long fracs. It was a shame that we could not meet up over new year but will be in llanfair again shortly

With dobs / newts the middle road is a 200mm or 8" after that the jump in apperture = more difficult to move, cool and use. The best scope is going to be the one you use the most. A friend has just bought a 14" dob, this is 'only'  6" more apperture than an 8" bt the eypiece is at 6 foot!

Best Regards

Damian

[Daveb3650]

That's a lot of kit....

[Moonshane]

It's a totally variable concept and dependent upon your own circumstances. This is likely to be the reason detail and advice is variable.

[John]

Many scopes seem "large" when you first unpack them and put them together in your lounge. You other half categorises them as huge and issues the "your not keeping that there are you ?" warning.

You then read that yours is thought of as "small to medium" in the overall scheme of things   

As Shane says it's a totally variable concept ......

[Charic]

Should we discussing Aperture and/or physical size? I`m assuming Aperture from the original post!

When I think of a bigger scope, I think aperture.

[AndyWB]

I thought my 10" was fairly large until SGL last year, where I was shown what 'large' was:

[Sirius Starwatcher]

The article that started my thread was from January Astronomy now mag page 47. It shows a photo of mercury with the text " how Mercury may appear in a small scope ". I fully appreciate seeing, Magnification etc but was trying to understand the sizing of scopes. Which has now opened up other possibilities as has been mentioned by Charic ie aperture/physical size. An interesting discussion.

[John]

Aperture what gives scopes their performance potential so Charic is correct. There are some scope designs which are physically large but have comparatively small apertures, eg: long focal length refractors.

[Moonshane]

Indeed. A 6" f11 frac and a 12" f5 dob have the same length but in my experience the latter is easier to mount and use.

[damnut]

Thats it, the whole apperture is king still reigns, you have to temper this with 'what you can expect to see'. In this respect the biggest difference is not magnification as the amount of light that can be collected with the larger scope. The planets might seem brighter but a 100x in a small 'scope' = 100x in a larger scope.

[Moonshane]

Aperture also equals resolution though so you potentially see more detail with more aperture even at the same magnification. Think hd TV compared with standard definition.

[Moonshane]

PS. If you don't believe the above, try your scope on Jupiter with the end cap on and the little cap removed and then remove the end cap. I am confident you will see more detail at full aperture.

[damnut]

Indeed and the contrast will be improved. = the greater light gathering power (dawes limit )

[brantuk]

It's arbitrary really but the Sky at Night used to define a small scope as a reflector <200mm (8") or a refractor <90mm (3.5"). Anything over those sizes was regarded as large. Turn Left at Orion mentions a small scope as a refractor of 2" to 3".

But there is such a vast array of different scopes these days that the boundaries are rather blurred. I would regard a dob >=16" diameter as large, Less than or equal to 10" dia as small, and anything in between as medium'ish. But I would be thinking of light gathering power - and coincidentally physical size follows the same track with dobs.

It's really whatever you decide in terms of light gathering power, physical size, footprint, weight, aperture or any combination thereof, for the category of scope you're looking at. Hth.

[LukeSkywatcher]

 For now I assume anything less than 6" is small, 8" to 12" as Medium and above 12" as large. 

Similar with focal ratios,  is there a  decisive cut-off between fast, slow, medium? 

We learn something everyday!

Sounds about right to me. If you check out the book Turn Left At Orion, they give an idea of what is small medium and large. I'd say 1-5 inch is small.................6-10 inch is medium and 10+ is large.

[Alien 13]

Oh my when I was a lad a 3" refractor was considered very large as was a 6" reflector anything bigger was out of range for most mortals.

Alan

[LukeSkywatcher]

Oh my when I was a lad a 3" refractor was considered very large as was a 6" reflector anything bigger was out of range for most mortals.

Alan

I dont really think aperture is a deciding factor on how good a scope is. My 70mm refractor scope is designed for wide field observing and it does it very well. My 90mm refractor is brilliant for observing planets. My 130mm Dob scope is good for a bit of everything (DSO are small), and my 200mm SCT is great for about everything in equal measure.