network profile
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Mar 29 |
awarded | Caucus |
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Jan 16 |
awarded | Scholar |
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Jan 16 |
accepted | Is overall light gathering of a lens only dependant on aperture? |
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Jan 15 |
awarded | Nice Question |
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Jan 13 |
comment |
Is overall light gathering of a lens only dependant on aperture? Oh yeah! Think things are making sense now. |
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Jan 13 |
comment |
Is overall light gathering of a lens only dependant on aperture? I think I've got it. Essentially for a F/0.95 50mm lens, the effective diameter has to be 52.6mm. That isn't particularly enormous, but to be that size, the lens would have to be able to focus light hitting the very edge of the lens back to the correct point of the sensor. Generally cheap lenses will not be able to achieve this, so even though the cheap lens may be 52.6mm or bigger, only light hitting fairly close to the centre can actually be used for a focused image - if you dismantled it to remove the aperture blades, you would get more light in, but not focused to an image. |
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Jan 13 |
comment |
Is overall light gathering of a lens only dependant on aperture? I understand the physical idea of stopping down a lens. Just because you've got a large lens doesn't mean you have to use it wide open. The bit I'm confused about is that the large aperture lenses don't seem to need to be as much bigger compared to the smaller aperture ones as I would expect. |
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Jan 13 |
comment |
Is overall light gathering of a lens only dependant on aperture? That does make sense but I still have some doubts. E.g. 50mm F2.8 here amazon.co.uk/exec/obidos/ASIN/B000GT11FI/watersphotogr-21/… versus 50mm F0.95 here noktor.com/products.php - by this formula, the numbers should be 52.6mm and 17.9mm, and the lenses don't look that far different. |
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Jan 13 |
awarded | Student |
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Jan 13 |
awarded | Supporter |
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Jan 13 |
comment |
Is overall light gathering of a lens only dependant on aperture? Just had a good look through that and I'm still left a bit confused! Does the aperture relate in some way to the diameter of the lens? |
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Jan 13 |
asked | Is overall light gathering of a lens only dependant on aperture? |
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Jan 13 |
awarded | Autobiographer |
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