In camera speak how do I compare zoom to mm...

[janzman]

A 'what you see' photo was taken with a 50mm lens.An magnified image was taken with a 75mm lens or 500mm or even 1000mm lens!!!!! for super close-up 'paparazzi' work.In digital cameras how do I equate lens mm to 4xoptical zoom,6x 8x or even 15x optical zoom.Please explain.

[jno]

it depends what the starting figure is, so you'll have to find that out from the specifications. A common starting point is 35mm, in which case a 10x zoom would be 350mm. If it's 28mm, which is fairly wide-angle, then 10x would be 280mm (and 20x would be 560mm). Mine starts at 25mm and has a 24x zoom, so that's a range of 25-600mm.

[jno]

trouble with interchangeable lenses (I used to have a film SLR) was that I always had the wrong lens on when a photo opportunity presented itself and by the time I'd changed lenses it had gone...

[Buenchico]

(2-part post):

I'm pleased that you started your question with some examples. It shows that you're familiar with the focal lengths used on 35mm SLR cameras, so you've saved me a bit of typing ;-)

However you need to be aware that, because the image is being focussed onto a CCD array (which is a different size to a 35mm film frame) the TRUE focal lengths of the lenses on digital cameras can be very different to those of conventional SLR lenses doing the same job. For example, a digital camera might use a (true) 10mm lens to take a 'what you see' picture, similar to one taken by the 50mm conventional lens referred to in your post.

Unfortunately, because the size of CCD arrays varies between cameras, there is no single conversion factor between the focal lengths of the lenses on film cameras and those on digital cameras.

Fortunately many (but my no means all) digital camera manufacturers refer to '35mm equivalent' focal lengths, which makes things a bit easier. (i.e. you can stick to the idea of a 30mm lens being 'wide angle', 50mm being 'standard', 80mm being 'short telephoto', 150mm being 'medium telephoto' and so on). Just to confuse things though, not all camera manufacturers calculate 'equivalent' focal lengths by the same method. (There are 3 different ways to do it!). So one manufacturer's lens described as 'equivalent to 50mm' might be slightly different to another manufacturers lens with the same description.

Having got all of that out of the way, I'll now attempt to answer your actual question!

All that a 'zoom' figure tells you is the RATIO of the shortest focal length of the lens to the longest one. So (using '35mm equivalent lengths') a lens which goes from 20mm (semi fish-eye) to 200mm will be a 'x10 optical zoom' lens. However a lens which goes from 50mm ('standard') to 500mm (longish telephoto) will also be a 'x10 zoom' lens.

So, if you really want some id

[Buenchico]

So, if you really want some idea of a camera's capabilities, you need to look beyond the 'optical zoom' figure and seek out the minimum and maximum '35mm equivalent' focal lengths.

Chris

[janzman]

Chris ...you are indeed a font of knowledge..thankyou.
EDDIE51..jno..thanx to you too

[society]

Hey Buen-Chris, do you remember my camera, the one I posted a while back and asked if it was a good one? It's the best camera, so far nothing negative about it. Thanks again for your help on that.