outrageous magnification claims

[Scott]

Ok, so we know that these claims by "toy" 'scope manufacturers are wrong if not in fact outright lies. What I want to know is how do they come up with these figures of say, 500x on a 60mm frac (I'm guessing at this figure). If it's just a number picked out of the air then why not 2000x? And if these numbers are unattainable, then how can they do it. Is it mathematically possible in earths orbit with no atmospheric disturbance and this is how they can get away with the claims? I just don't understand how they can advertise these claims if it's not at least theoretically possible.

answers on a postcard please

[JamesF]

I imagine purely by calculating the magnification based on the focal length of the OTA and eyepieces they supply.

James

[Moonshane]

I think James is right. if you had a 500mm focal length and they supply a 2x barlow it is possible to get a 2mm eyepiece so 500x is theoretically possible albeit impractical in every sense with this sort of scope.I use 500x with my scopes though on double stars and moon occasionally. they are substantially more than 60mm aperture though.

[Scott]

so it doesn't have to actually work then? It's a bit like saying your car will do 250 miles an hr because thats what the speedo goes up to.

[Moonshane]

that's the problem with these scopes, completely misleading. a member of SGL is on a crusade to get these scopes (or claims anyway) banned.

[Mattscar]

I believe these are the droids your looking for...

http://stargazerslounge.com/topic/175866-misleading-telescope-advertising-asa-complaint/

[Moonshane]

indeed thanks Matt - found it much quicker than me!

[Scott]

ah yes, I have seen this thread. surely the formula (f/l x e.p. = mag) is wrong in that it's only part of the formula which should also contain something about apeture and atmosphere. If they are to use maths to reach an answer then surely they must use the whole formula or at least one that works.

then again, I guess i'm stating the obvious

edit:- oh yeah, and the quality of the optics

[Moonshane]

as you say, not wrong just incomplete.

[Scott]

as you say, not wrong just incomplete.

I would argue that in this instance, incomplete is wrong

[Mattscar]

indeed thanks Matt - found it much quicker than me!

HTH I have it in my 'content I follow' list.

[JamesF]

The ASA's point of view, at least, appears to be not so much that "it doesn't work", but that "it isn't useful for any purpose". The former would probably get them to take action as it's claiming something that isn't possible, whereas the latter won't.

Personally I think they're trying to get themselves off the hook and trying to avoid taking action. If a telescope didn't produce a clear image at any magnification then I think they'd agree that it wasn't fit for purpose. I can't see that it's then reasonable to say it's ok if it does produce a clear image at some magnifications, just not the one advertised on the box. I'm actually quite disgusted with their attitude, because what they're effectively saying is that it's ok for the manufacturers to deliberately mislead the purchaser.

James

[faulksy]

I think James is right. if you had a 500mm focal length and they supply a 2x barlow it is possible to get a 2mm eyepiece so 500x is theoretically possible albeit impractical in every sense with this sort of scope.I use 500x with my scopes though on double stars and moon occasionally. they are substantially more than 60mm aperture though.

I think James is right. if you had a 500mm focal length and they supply a 2x barlow it is possible to get a 2mm eyepiece so 500x is theoretically possible albeit impractical in every sense with this sort of scope.I use 500x with my scopes though on double stars and moon occasionally. they are substantially more than 60mm aperture though.

wow that's a lot shane, must be one fine scope. who ever made it must be good :grin:

[Scott]

Anyway, thanks guys. I was just wondering how they derived their mags and i'm sure you have all heard the rantings of an annoyed astronomer too many times to mention. It really is wrong though . nuff said

[SnakeyJ]

I thought these events were mainly for the lx imagers - but this could just be possible with an 8" scope - so I will definitely be having a good look if the skies clear next week.

Not quite sure how this ended back on this page - I was composing a reply on the bottom of when a notification popped up about another reply

[Scott]

wow that's a lot shane, must be one fine scope. who ever made it must be good :grin:

yes faulksy, it would be nice to look through one of these "shanebuilts" one day

[ronin]

Problem is if the scope has a focal length of 1000mm and they supply a 4mm eyepiece and a 2x barlow then the magnification comes out as 500x. They do not I suspect say a wonderfully clear image at 500x, just you can get 500x. On a sheet of paper and with 1 line you get 500x.

That is what the rules give.

Will equally say that occasionally I read of people here claiming magnifications way above what I would expect from any scope, sure I have read a couple of posts of 600x and over.

Unfortunately it happens that when most people look at a scope purchase the primary factor is usually "What magnification can it give?" When many buy a scope often the question appears where can I get a good 3mm or even 2mm eyepiece to give me NNNx magnification.

A person will look at 60mm Mega-Scope saying 200x and 60mm Super-Mega-Scope saying 500x and buy Super-Mega-Scope and other then the name and possibly a colour difference, Super-Mega-Scope of course being RED there will be no difference. It is human nature and marketing.

Hell people buy mountain bikes because they have 27 gears, many will not be able to count to 27 and 12 of the gears will never be used. But they still pay that bit more for the 27 rather then a 12 or 15 geared mountain bike. It happens everywhere.

[Scott]

I thought these events were mainly for the lx imagers - but this could just be possible with an 8" scope - so I will definitely be having a good look if the skies clear next week.

Not quite sure how this ended back on this page - I was composing a reply on the bottom of http://stargazerslou...ova-in-ngc4414/, when a notification popped up about another reply

Haha Jake, thanks for the edit, I must admit I was doing a fair bit of head scratching there

[Scott]

Problem is if the scope has a focal length of 1000mm and they supply a 4mm eyepiece and a 2x barlow then the magnification comes out as 500x. They do not I suspect say a wonderfully clear image at 500x, just you can get 500x. On a sheet of paper and with 1 line you get 500x.

That is what the rules give.

Will equally say that occasionally I read of people here claiming magnifications way above what I would expect from any scope, sure I have read a couple of posts of 600x and over.

Unfortunately it happens that when most people look at a scope purchase the primary factor is usually "What magnification can it give?" When many buy a scope often the question appears where can I get a good 3mm or even 2mm eyepiece to give me NNNx magnification.

A person will look at 60mm Mega-Scope saying 200x and 60mm Super-Mega-Scope saying 500x and buy Super-Mega-Scope and other then the name and possibly a colour difference, Super-Mega-Scope of course being RED there will be no difference. It is human nature and marketing.

Hell people buy mountain bikes because they have 27 gears, many will not be able to count to 27 and 12 of the gears will never be used. But they still pay that bit more for the 27 rather then a 12 or 15 geared mountain bike. It happens everywhere.

I understand what you are saying here Ronin, but surely fit for purpose has to count for something.

[allcart]

I understand what you are saying here Ronin, but surely fit for purpose has to count for something.

I'm sure it does, thats why returns warehouses are stacked up with cheap telescopes that nobody wants. I have a friend who works for a company that sells scopes through Amazon. I have been gobsmacked by the pallets of returns he has to deal with. Nothing physically wrong with the scopes except that they were bought, tested and returned as unwanted.

Yes !! they are all under 80mm.

[Laurie61]

Quite often these high mag figures are derived from the old rule of thumb calculation, this is 50x per inch, 2x per mm, of aperture. This will give you a .5 mm exit pupil considered to be about as small as

you can comfortably go. I found a table which suggests that you can see all the detail/resolution provided by a scope before you get to this point.

[Laurie61]

Magnification Table.