working out the zoom figure on a DSLR lens

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rabaroo

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Hi

on a compact camera it says 3x zoom for example.... how do you work out the equivalent zoom factor on a DSLR lens? - e.g. if you have a kit lens of 18-55 or 28-105 - how much zoom is it?

whats the equation?
 
I think you divide the long end by the short end, so for the kit lens, 18-55 is 55/18 or about 3x.
 
As John says.....the 3x bears no relationship to magnification when specifying it on a lens. It is simply the range of the focal lengths from wide to long.

Bob
 
Its a term that really bugs telescope owners. All this talk of X magnification is [PLEASE DON'T TRY TO BYPASS THE SWEAR FILTER] to be honest. Its the actual focal length that matters. The magnification is down to the size of the eyepiece you use.
In a similar vien are these camcorders with 100X zoom!!! (Yeah right!)
 
Indeed. The X Zoom is irrelevant in SLR lenses as it depends on the focal range of the lens and what you want to do with it. In compacts, the wide end is pretty standard (In most cases anyway) so the more X Zoom, the more focal length and this can be used as a sales point by the manufacturer. With SLR lenses, the wide end can be one of many focal lengths. Mind you, that doesn't stop Tamron advertising the 18-250 as "13 X Zoom!" ;)
 
The camcorders with huge zoom levels only go to a certain length in optical zoon, then converts to digital - grabbing pixels and then enlarging them, the quality is shocking!!!

I would only EVER look at optical zoom... In terms of how it's worked out, sorry, I don't really know :-(
 
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