How are digital f2.8 zoom lenses so cheap and a film one cost the earth?

This is a question i have been confused by since quite some time...
How is it that a film zoom ( for an SLR for eg.) can cost the earth if it is f2.8 even if it uses the cheapest glass BUT a digital olynpus 38-380mm f2.8/3.4 lens + camera can come for under $400?
A Canon 2.8 zoom comes for around $1500 and i know that the a 50mm1.4 is 3X the cost of a 50mmf1.8 so obviously smaller aperture lenses are very expensive, the cost difference cant be explained solely on the basis that the glass used in digital P&S is cheap and the SLR lenses have expensive glass.

Does this mean that the meaning of aprture changes for digital cameras,making it easier to manufacture?

Thanks in advance
Kunal

It's all in the SIZE of the glass. Aperture is relative to sensor size. Those lenses are TINY but can still reatin f/2 or slower apertures relatively easily. Film is much larger, and requires much larger glass to get a fast aperture.

The bigger the glass the more it costs.

The digital doesn't actually have a 38-380mm lens.

It's focal length ranges from 6.3 -63mm. These give a view equivalent to 38-380 on 35mm film.

The f no is basically the ratio of the lens's focal length to the aperture diameter.

As the focal length is quite small a small diameter aperture still gives a large f no.

Quote:

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Originally Posted by straightarm

The digital doesn't actually have a 38-380mm lens.

It's focal length ranges from 6.3 -63mm. These give a view equivalent to 38-380 on 35mm film.

The f no is basically the ratio of the lens's focal length to the aperture diameter.

As the focal length is quite small a small diameter aperture still gives a large f no.

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Sheesh completely forgot my fundamentals! Thanks