[Tfug] Way OT: optics mumbo jumbo

[Robert Hunter]

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On Tue, Mar 18, 2008 at 08:49:28PM -0700, TR wrote:
> On Tue, Mar 18, 2008 at 8:11 PM, Bexley Hall <bexley401 at yahoo.com> wrote:
> >  Now, my naive question:  by doing this, am I,
> >  to some extent, counteracting the effect of
> >  "moving away" from the target?  I.e., does
> >  the magnification I am bringing in to play
> >  *increase* the amount of light that strikes
> >  the (digital) film?
> Yes and no. as you move away the light returning from the subject
> lessens.  But the camera is always trying to make the average light on
> the film plane the same.  So it either it pumps more light to the
> flash. opens the appeture to let in more light.

Hi, Don.

You can also decrease shutter speed to get more exposure, but you may
need a tripod to prevent motion blur.  Increasing ISO also helps to
some degree, but I am not entirely familiar of when it is or isn't
useful.  Keep in mind that a larger aperture will reduce your depth of
field; but by the sound of it, that may not be a concern for you.

- --Rob
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