Lens Speed
- Thread starter Frey
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It'll say on the front of it, XXmm then 1:X the smaller the number after the 1: the quicker it is (wider aperture).
This lens is F4 - 5.6, a slow lens in comparison to say an F2.8 of the same focal length or something like a 50mm F1.8, generally the faster they get the more pricey they get.
This lens is F4 - 5.6, a slow lens in comparison to say an F2.8 of the same focal length or something like a 50mm F1.8, generally the faster they get the more pricey they get.
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TCR4x4
Wishes he had a couple more Inches
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- Tom
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By the aperture listed on the barrel.
If its f/3.5-5.7 then its not very fast.
Is its f/1.8 then it is.
The speed refered to is the maximum aperture, as the higher the aperture, the faster shutter speed you can get.
If its f/3.5-5.7 then its not very fast.
Is its f/1.8 then it is.
The speed refered to is the maximum aperture, as the higher the aperture, the faster shutter speed you can get.
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- Andrew
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The F number is the ratio of the focal length of the lens to the diameter of the aperture. So with a 50mm: F2 lens the diameter of the aperture is 25mm.
For a 50mm: F1.4 the diameter is a tad over 35mm. A 300mm F2.8 is 107mm, while a 300mm: f5.6 is only 35mm.
The larger the diameter of the aperture lets in more light, so you can use a faster shutter speed or a lower ISO.
For a 50mm: F1.4 the diameter is a tad over 35mm. A 300mm F2.8 is 107mm, while a 300mm: f5.6 is only 35mm.
The larger the diameter of the aperture lets in more light, so you can use a faster shutter speed or a lower ISO.
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- Shayne
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All the definitions can be so confusing at first (it was for me). I read all the definitions but it wasn't until I went out (in manual mode) and tried the different Fstops to see how they effected my exposure till I figured it out. From one beginner to another, forget about the numbers for now and watch your exposure. The numbers (fstops) will all come together. That's what I did and it worked for me. Hope it helps. Oh and then come back and read all these great helpful post from the guys who really know what their doing.
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- Adrian
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A friend once asked me about what makes a lens 'fast' and by the time he was satisfied with my explanation, he told me that it was "rubbish and wrong" because it's the shutter speed of the camera body which is faster and not the lens - it is wider. :bang: Still, he's got a point.