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10-26-2009, 03:40 PM   #1
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"stop down" meaning

what does this mean in time exposure
thanks

10-26-2009, 03:52 PM   #2
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QuoteOriginally posted by eric59 Quote
what does this mean in time exposure
thanks
"stop down" means to close the aperture on the lens so that the opening gets smaller (ie. to go from f2.8 to f11; or from f4 to f22). You can do this from the camera wheel with a modern lens, or using the aperture ring on the lens itself if it is an older lens.

Also, when using older lenses on a DSLR you can meter in Manual mode by pressing the green button or AEL button (depending on camera type). This will cause the camera to close the aperture (stop down) and take a meter reading. You can then take the picture.

Lastly, if you operate the DOF lever while looking through the viewfinder, the camera will stop-down the lens to show you the DOF you can expect in the picture you are about to take.

The more you stop-down, the longer the shutter has to remain open to get the correct exposure.
10-27-2009, 06:30 AM   #3
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QuoteOriginally posted by eric59 Quote
what does this mean in time exposure
thanks
Peter's response is correct. "Stop down" means to adjust the f-stop so the aperture narrows. You might do this for different reasons, but one common reason is to achieve greater depth of field.

I would comment on just one small thing that Peter said: "The more you stop-down, the longer the shutter has to remain open to get the correct exposure." That's the way most of us think about it most of the time, and it responds to your question. I just want to add that there are a couple of other things that may be important to remember. Stopping down does NOT always increase the shutter time required for a correct exposure.

For example, say you like the shutter speed you're using already (say it's 1/30th sec and you don't want to go faster because you're shooting a river and you want the water to blur into a smooth flow), although your trial shot seems a bit overexposed. In this case, you might stop down a bit, leave the shutter and ISO alone, and get the right exposure. In this example, the original exposure settings were incorrect and you stopped down to correct them.

Remember also, that shutter speed and aperture are not the only camera settings that affect exposure - there's also ISO. Stopping down can be offset by increasing the ISO rather than slowing down the shutter. We used to think of ISO as a fixed number at least until we finished the current roll of film, but these days, it's possible to change ISO from shot to shot and sometimes it makes sense. This may be especially true if you're shooting with a flash, since aperture and shutter speed work somewhat differently in flash photography than in available-light photography.


Will
10-27-2009, 04:15 PM   #4
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thanks

that helps alot.
eric

10-28-2009, 11:12 PM   #5
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QuoteOriginally posted by WMBP Quote
Peter's response is correct. "Stop down" means to adjust the f-stop so the aperture narrows. You might do this for different reasons, but one common reason is to achieve greater depth of field.

I would comment on just one small thing that Peter said: "The more you stop-down, the longer the shutter has to remain open to get the correct exposure." That's the way most of us think about it most of the time, and it responds to your question. I just want to add that there are a couple of other things that may be important to remember. Stopping down does NOT always increase the shutter time required for a correct exposure.

For example, say you like the shutter speed you're using already (say it's 1/30th sec and you don't want to go faster because you're shooting a river and you want the water to blur into a smooth flow), although your trial shot seems a bit overexposed. In this case, you might stop down a bit, leave the shutter and ISO alone, and get the right exposure. In this example, the original exposure settings were incorrect and you stopped down to correct them.

Remember also, that shutter speed and aperture are not the only camera settings that affect exposure - there's also ISO. Stopping down can be offset by increasing the ISO rather than slowing down the shutter. We used to think of ISO as a fixed number at least until we finished the current roll of film, but these days, it's possible to change ISO from shot to shot and sometimes it makes sense. This may be especially true if you're shooting with a flash, since aperture and shutter speed work somewhat differently in flash photography than in available-light photography.


Will
You NAILED IT!!!!!!!
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