F stops on slr like digital cameras - Digital Darkroom Forum

Hi John,

First off - this is probably not the best forum to ask this - since it should be all about post-processing - and your question would be more appropriate to the Digital Photography Q&A forum. In any case....

Aperture for the FinePix S9000/S9500 is listed by Fujifilm as being "F2.8 to F11; 13 steps in 1/3 EV increments Manual/Auto selectable"

I guess you are referring to the published _lens_ specs of F2.8-4.0 this is likely (though you can never absolutely guarantee with con/prosumer cameras!) to relate (as it does with other lenses) to refer to the maximum aperture at each end of the range - ie at 28mm equiv. then your max aperture is F.2.8 and at 300mm equiv. it will be 4.9.

lens specs rarely give a _minimum_ aperture size.

To answer your second question - indeed a smaller aperture (larger f number) will give a greater DoF on digital as well as film cameras. The simplified psuedo-physics is fairly easy -

an out of focus point of light does not hit the sensor plane as a 'dot' but a circle (bigger for more out of focus) - the smaller the aperture - and the smaller the circles - hence a greater range will appear as (or very close to) points or 'dots' instead of circles - so the effective 'in-focus' range (or DoF) is greater.

If you are interested, I'm sure I could find a description on the net somewhere with pictures and everything!!

Hope I helped!

Steve

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