Author Topic: Achieving a desirable DOF  (Read 1574 times)

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Offline skmalladi

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Achieving a desirable DOF
« on: May 07, 2009, 04:10:59 PM »
I remember reading some place that a shallow DOF is achieved by using a small f-stop, a large focal length and getting really close to the subject.

Is this correct? Can someone give a few examples of achieving a good DOF in practice?

Usually the shallowest possible DOF seems to be what a lot of people seem to wish for, but that would be like asking for power for the sake of power rather than exercising it wisely. Hence my request of examples and tips from more experienced folks.

Thanks,
Sashi

Offline Stef.

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Re: Achieving a desirable DOF
« Reply #1 on: May 07, 2009, 06:35:06 PM »
Sashi- shallow depth of field is achieved by choosing a wide aperture such as f1.2 -> f4... the smaller the number the wider the aperture and the smaller the dof.
How much or little dof you want for oyur image depends on a lot: if you shot landscape you want generally speaking a greater dof so you would choose something between f11 and f32. I you shot a close portrait of somebody you would choose a wider aperture suchh as i.e. f1.4 ->2.8. For macro shots- because you are so close with your lens to the subject you would choose a small aperture to get as much dof as possible. Sometimes the dof is not choosen for artistic reasons but purely because thelight is so bad that you have to open up your aperture to the widest possible. Finally the shallower the dof the more critical it becomes that the right focus point is choosen- i.e. the eye in a portrait and not the nose!
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Offline tpe

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Re: Achieving a desirable DOF
« Reply #2 on: May 07, 2009, 06:39:41 PM »
Another thing that makes a wide apperture lens an advantage is its light gathering ability. The bigger the hole the more light that can get through it in a given time the faster the shutter speed for a given exposure. Very usefull for getting rid of camera shake and can give you sharper shots by opening up the apperture. If you get to longer length lenses such as telephoto for wild life a large apperture can be priceless, as long lenses show any camera movement more and so the ones with the larger appertures. Larger appertures also means a bigger lens is needed to direct enough light to fill the the appertue so putting the price up.

tim