Why do older camera lenses have faster F-stops?

Started Apr 14, 2013 | Discussions thread
hha
hha
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Re: Why do older camera lenses have faster F-stops?
In reply to vjk2, Apr 14, 2013

vjk2 wrote:

Could it be...what, autofocus, maybe the zoom design that makes modern lenses so dim?

There are at least two reasons:

In the classical lens design the whole lens ensemble moves for focusing. This was abandoned  in the early 90s to allow the autofocus design, where only one or two small lenses of the whole lens assembly (maybe 10 lenses or more) needed to be moved. This makes the design more costly and/or more sensitive to  miss-alignment.

The lenses of the 80s were designed with a 30 micron blur spot at maximum aperture. Some of the professional Nikon lenses reach a 10 micron blur spot. With the advent of digital cameras with 4 micron pixels and smaller, the corner softness and the flair of even the best lenses from the 80s at maximum aperture is disturbingly obvious.

For some applications, like astrophotography, some of the old lenses are still unequaled, particularly if they are used in the APC format.

hha

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