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#1 Annemarie van Basten

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Posted 31 July 2008 - 10:55 AM

Just a quick question. I am studying still and for the frist time i'm allowed to use prime lenses. I just want to know, why whould i want to use for example a 35mm prime lens if I can just use a 12-120mm zoom and set it to 35mm? what is the difference, positives/negatives of both? :unsure:
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#2 David Mullen ASC

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Posted 31 July 2008 - 11:02 AM

Primes generally are lighter, smaller, faster, breathe less, flare less, and focus closer than some zooms -- otherwise, zooms are fine... ;)

But you have to compare apples to apples -- modern zooms to modern primes. With older lenses, anything goes. Though an Ang. 12-120mm is not a particularly sharp lens.
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#3 K Borowski

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Posted 31 July 2008 - 12:30 PM

But you have to compare apples to apples -- modern zooms to modern primes. With older lenses, anything goes. Though an Ang. 12-120mm is not a particularly sharp lens.


As a proud owner, I resent that implication David. It's not a particularly sharp lens *wide open* but it is tits at T5.6 or smaller stops :P
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#4 John Holland

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Posted 31 July 2008 - 12:45 PM

I think its pretty good at T4 , but i am not one of the people who demand pin sharpness or no grain . :huh:
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#5 Stephen Williams

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Posted 31 July 2008 - 12:46 PM

As a proud owner, I resent that implication David. It's not a particularly sharp lens *wide open* but it is tits at T5.6 or smaller stops :P


Hi,

Most lenses are sharp stopped down to T5.6, it's how they perform at T2.8/4 or wider is more useful IMHO.

Stephen
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#6 Ira Ratner

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Posted 01 August 2008 - 07:25 PM

How come no one mentioned lens speed?

AnneMarie, a "faster" lens, one with a wider maximum aperature (F 1.4 as opposed to 1.8) doesn't become that way just because the manufacturer decided to stick the 1.4 setting on its aperature ring. The optics of the lens--the glass and its assembly--have to actually allow so and so much light in to correctly give it that designation.

And that means great glass and assembly to be able to DO that. Because remember--all manufacturers are stuck to the same confines of the diameter of the lens for that camera. Making the lens physically longer is no help at all--because now you've increased the distance (in the the lens) that the light has to travel to make contact with the film. And you can't make the lens any wider to accept more light because you're stuck with the confines/dimensions/physics/geometry of your film.

So faster lenses not only let more light in, allowing you to expose less sensitive/lower ASA/ISO film under low light conditions, but by their very nature of being faster, they're optically cleaner and superior to slower lenses--REGARDLESS of the aperature you're using. They're simply "better" across the board.

Which is why zoom lenses can rarely match primes. By their very nature and assembly, they're slower and never match the quality and speed of a good prime.

Mind you--I'm talking about lenses that us normal people can afford.
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#7 Ira Ratner

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Posted 01 August 2008 - 07:38 PM

Ooops:

David did indeed mention lens speed, but I gave the Idiot's Guide explanation of it.

Edited by Ira Ratner, 01 August 2008 - 07:40 PM.

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#8 Sam Wells

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Posted 01 August 2008 - 08:54 PM

So faster lenses not only let more light in, allowing you to expose less sensitive/lower ASA/ISO film under low light conditions, but by their very nature of being faster, they're optically cleaner and superior to slower lenses--REGARDLESS of the aperature you're using. They're simply "better" across the board.


This is in no way a true statement.

=Sam
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#9 Ira Ratner

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Posted 02 August 2008 - 07:00 AM

This is in no way a true statement.

=Sam


I stand corrected then--I'm going by 1980 standards where zooms, dollar for dollar, didn't stand up to primes.
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#10 K Borowski

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Posted 06 August 2008 - 11:28 AM

Hi,

Most lenses are sharp stopped down to T5.6, it's how they perform at T2.8/4 or wider is more useful IMHO.

Stephen


Look at it this way: with 400T VNF shot in the wrong color temperature a stop underexposed, the softness of the lens is a blessing in disguise for their original intended purpose of newsgathering! ;)
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