Microscope/Telescope magnification claim

[gumboot]

I came across an advert in the Daily Telegraph on Saturday for a combined pocket sized microscope/telescope. The thing looks like a short tube with an eyepiece at one end and a lens behind a triangular shaped metal piece at the other. It's said to be less than five inches long and comes with a pocket clip.

A photo of the device clearly shows the body of the device marked "6X Telescope, 24X Microscope".
The advert text does not mention these magnifications, but it does state "600% magnification telescope" and "2400% magnification microscope". The text also claims the microscope is capable of seeing "an amazing 2400% bigger".

Maths was never my strongpoint, so what I'd like to know is do these percentage magnification claims tie in with the magnification of the device eg if the microscope magnifies something by 24X, is it really 2400% bigger?

This seems very dubious to me.

[rojash]

Yes (ish).

Personally I would have thought that:

1 x = 0% magnification (ie the same size)
2 x = 100% (twice as big)
3 x = 200%
4 x = 300%
5 x = 400%
6 x = 500%

But maybe a magnification of 1x is twice the size!

[mibn2cweus]

The thing to keep in mind when using percentages is the hidden feature of the denominator, one hundred. This means that values represented in per/cent are magnified one hundred times.

A "magnification" of one-half power (minus 50%) would be half the size!

[gumboot]

Thank you both.

It's certainly an idea rojash that they may be basing the calculation on a magnification of 1x being twice the size. This would account for their percentage figure of 2400%.

All the same, I always thought that 2x meant something was magnified twice the size - at least that's what it was when I last peered down a microscope in the school biology lab.

It's all very odd. Any other thoughts?

[jake-the-peg]

If you ever see adverts going on about the magnification run very fast in the opposite direction.

The main lens (or mirror) on a telescope has a focal length, the distance bewteen the lens and it's focus.

The eyepiece has a focal length too.

To get the magnification you divide the first by the second.

You can get any magnification from a telescope merely by using a eyepiece with a small enough focal length.

You could put in one to give you a million times magnification, but the image would be so faint you'd not see a thing and even if you could it would jump all around from the tiniest vibration.

The quality of a telescope is in it's lenses or mirrors. They should be achromats (so the colours are not split out) they should be ground parabolically so there is no so called spherical aberation. They should be well "bloomed" to capture the maximum amount of light and should have a good mount (preferably equatorial for astronomy) .

[Dagman]

I had one of these years ago (someone must have found a stash of them again) and it's absolute tat, don't bother. the microscope is no better than a magnifying glass and the telescope is, well, useless. It doesn't let enough light through to see anything, very dull/grey images! learn from my mistake folks!

[gumboot]

Thanks jake-the-peg and Dagman. I'll follow your advice!