 BetterPhoto Member |
f-stops and focal lengths 1) what will be the impact on your f-stop setting when you speed up your shutter setting for freeze action? 2) what impact does the focal length have on a slow shutter speed?
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Raphael Chan |
Your questions need more specific,I will try to answer them: 1. If it is manual camera,speed up shutter setting means use low number of f-stop(larger diaphragm), unless you switch to high speed film. If it is auto camera, it will adjust the f-stop by itself when you preset the shutter speed. 2.Slow shutter speed means allow you using high number of f-stop, hence increase the focal length(we call it Depth of field).
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Raphael Chan |
Your questions need more specific,I will try to answer them: 1. If it is manual camera,speed up shutter setting means use low number of f-stop(larger diaphragm), unless you switch to high speed film. If it is auto camera, it will adjust the f-stop by itself when you preset the shutter speed. 2.Slow shutter speed means allow you using high number of f-stop, hence increase the focal length(we call it Depth of field).
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Michael Kaplan |
1) For each increase in shutter speed you get 1 decrease in aperture (the F stop gets smaller in number which is larger in size or more open) i.e. If your exposure should be 1/250 sec @ F5.6 then 1/500 = F4 or 1/125 = F8. Each time you speed up the shutter you need to allow in more light to make up the difference so you can only speed up (or slow down) with any combination that will work for your particular lens/camera setup. If your lens in the above example has a maximum aperture (minimum F stop) of F4 then you could not shoot that picture at 1/1000 second or faster because that is the maximum your lens can open so your picture would be under-exposed. 2) What impact does the focal length have on a slow shutter speed? A couple of things. 1st, it affects your being able to handhold the camera. You should be hand holding a camera only if you are shooting at the reciprocal of the 35mm focal length or faster. If you are at 200mm then you should be at a minimum of 1/200th second or faster or chances are you will get a blurry picture just from camera movement. That is where a lens with IS (Image Stabilization) comes in if you can afford it. So if you were to want to shoot at 1/30 second you would need to be using a lens at 30mm or wider or use a tripod or flash. 3) 2nd, DOF or Depth Of Field. The longer your lens (greater number in mm, the less depth of field you have at any given distance. You will have more of the background out of focus using a 135mm lens in a portrait of someone 10’ away than if you used a 50mm to shoot that same picture. That is why the 135mm lens is preferable for portrait work than the standard lens size of 50mm. Also you get a more compressed background m3eaning if 2 people are 10’ distance from each other and you shoot the 2 of them, the longer lens will make them look closer together than if you used a 35mm lens. Hope this helps.
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