Focus

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What is it called when you have an image in focus and the area that is in focus is very shallow vs. when everything in the frame is clear? How can I get that setting to do what I want and when??

 

[Torus34]

The range of sharp focus, front to back, is called the 'field' of sharp focus. Its 'thickness' is referred to as its 'depth.' Putting these together, we get the phrase 'depth of field.'

If the physical depth of this range of sharp focus is small [compared to the scene,] we speak of a 'shallow' or 'narrow' depth of field.

The depth of field relates directly to the aperture [or 'f' setting,] of the lens. As the physical diameter of the aperture in the lens increases [smaller 'f' number,] the depth of field will decrease [becomes more shallow.] Smaller apertures [larger 'f' numbers,] provide greater depth of field.

 

[ksmattfish]

DOF is controlled by several things. Most folks only have to worry about the first 3 on this list. If you google "DOF calculator" you will find online help where you can input these factors, and it'll calculate the DOF.

deep DOF<------------------->shallow DOF
small aperture (big f/#)<------>large aperture(small f/#)
shorter focal length<---------->longer focal length
far focus distance<----------->close focus distance
smaller format camera<------->larger format camera

 

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Thank you guys!