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Old Jun 28, 2005, 3:25 PM   #1
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"You had the camera set at 1/2000th, in Shutter Priority (Tv) mode. The 75-300mm lens you have has a variable maximum aperture of f4 at 75mm to f5.6 at 300mm.

What that means is that, since your lens was zoomed in at 135mm when you took that picture, it was impossible for the camera to open wider than f4.5."

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Old Jun 28, 2005, 3:29 PM   #2
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Ladythump wrote:
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"You had the camera set at 1/2000th, in Shutter Priority (Tv) mode. The 75-300mm lens you have has a variable maximum aperture of f4 at 75mm to f5.6 at 300mm.

What that means is that, since your lens was zoomed in at 135mm when you took that picture, it was impossible for the camera to open wider than f4.5."
It means that the largest aperature the lens is capable of changes according to the focal length of the lens. At 75mm the max is f/4 andat 300mm the max is f/5.6 and it varies in-between those two points.
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Old Jun 28, 2005, 3:35 PM   #3
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so should i set my apeture in between those two numbers?
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Old Jun 28, 2005, 3:49 PM   #4
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No, that's just the maximum aperature at a particular focal length. The minimum aperature is usually constant regardless of the focal length, probably f/18 or f/22, something like that. So, it would work like the example chart below:

75mm - max aperature = f/4 - min aperature = f/22
135mm - max aperature = f/4.5 - min aperature = f/22
300mm - max aperature = f/5.6 - min aperature = f/22

So, the f/22 part stays constant. So, you could take a shot at 120 mm and f/4.5 all the way to f/22. And of course, f/22 will let the least amount of light through. Or at 75mm and f/4 all the way to f/22.

It just depends on the shot and the lighting conditions as to what combination of shutter speed and aperature you need.
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Old Jun 28, 2005, 4:23 PM   #5
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I"m trying to shoot mostly wakeboarding pictures and softball.



If I use my zoom lense for wakeboarding and go with:

1/1000 @ f4.5 ISO 100



will my lense handle that?
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Old Jun 28, 2005, 4:39 PM   #6
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It depends on how much you zoom it. At 300mm, you'd be able to do the followig:

1/1000 @f/5.6 ISO 100 because at full zoom, the lens can only open to f/5.6. But, you probably don't need to use 1/1000, as that will completely freeze the action and not give any sense of motion. You're going to have to play with settings, as it's going to depend greatly on the amount of lite there is.

Perhaps something like 1/500 @ f/8 ISO 100 will work well enough if it's bright out.

Really, you just gotta take several shots at different settings and see how they turn out to know for sure.
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