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06/02/2004 04:45:23 PM · #1 |
Why cant you physically remove an aperature blades from a lens to make it a wide open lens? I mean like opening up the lens, and carefully taking the blades out. can it be done? why or why not?
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06/02/2004 05:45:54 PM · #2 |
LOL, why would you want to? I'm sure it's impossible to do without destroying the lens.
The reason they only open so wide (ie. F2, whatever) is because the lens probably wouldn't work with no blockage of light. That's why lenses that allow very large appratures are expensive, because it takes more "engineering" to design them to handle the extra light.
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06/02/2004 06:08:46 PM · #3 |
Originally posted by ChrisW123:
LOL, why would you want to? I'm sure it's impossible to do without destroying the lens.
The reason they only open so wide (ie. F2, whatever) is because the lens probably wouldn't work with no blockage of light. That's why lenses that allow very large appratures are expensive, because it takes more "engineering" to design them to handle the extra light. |
I don't understand why it would be a problem to handle the extra light, could you explain? It was always my understanding that the longer a lens and the more glass it has inside, the more difficult it is to get enough light through it, i.e., telezooms have smaller effective apertures than wide angle lenses. Getting a larger effective aperture would require clearer glass and a wider bore of the tube, which makes it more expensive. But this is totally intuitive, so I'm open to any explanation of why this would be the case. Inquiring minds would like to know!
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06/02/2004 06:29:09 PM · #4 |
Think about it this way -- if the optical design of a lens allowed for a larger maximum aperture, don't you think the manufacturer would have designed it that way in the first place? Large maximum apertures are the "holy grail" of lens design, and making "fast" lenses (that is, lenses with large maximum apertures/small Æ’-numbers) is a design trade-off. Have you ever seen how big the diameter of the front element is on something like a 400mm Æ’/2.8 lens? Compare that to the diameter of a 400mm Æ’/5.6 lens... lens design is about more than just the maximum opening of the internal aperture blades!
Message edited by author 2004-06-02 18:33:17. |
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