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Re: filmscanners: OT: Places to ask about lenses?

Rob Geraghty wrote:

>>In optics the rule: "you get what you pay for" has almost 100 % meaning...
> I'm usre this is generally true, although I imagine there's such a thing as
> limiting returns.  I find it hard to believe that the price difference
> between the Pentax 50mm f1.7, f2.8 and f1.4 lenses would be obvious in the
> results.  I'd like to have at least one lens I *know* is as sharp as I can
> afford.
> Rob

Oddly, although I am sure, as Rob says, this is true in the big picture 
(a $1000 lens is going to be better than a $100 one), I have found it 
really doesn't necessarily hold water in the "macro" view. (A $200 lens 
is better than a $100).  Canon, for example, has all sort of overlapping 
ranges of lenses in terms of both quality lines and focus ranges.  Some 
lenses which are very reasonably priced, as stellar performers, while 
other considerably more expensive lenses are duds.

Sometimes this is just bad design, or even bad manufacture, but 
sometimes a simple and inexpensive lens design just happens to be one 
which really works well, and has great optical properties.

One apparent example of an inexpensive lens which excels well beyond 
it's cost it the autofocus Canon 50 mm 1.7 normal lens.

Of course, beyond optical qualities, other factors are durability over 
time, weight, size, smoothness in use, zoom range, optical speed 
(minimum/maximum aperture), autofocus speed, autofocus noise level, etc.

If people aren't stuck on having a full zoom range, in general, fixed 
focus lenses are better quality and better value.  Also, used lenses can 
often be good value, if they come with some type of warranty.

Lastly, even a well rated lens can perform badly due to bad quality 
control and variability within production.



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