Circular Polarizing Filter for outdoor shooting

[FaithfulPastor]

First, to the Moderators, please move this to the correct forum as you deem necessary.

If I'm shooting people outdoors, in daylight, and using only fill flash, should I shoot with the CPF on or off?

Is there a general rule such as, shoot with it on unless you must remove it or the reverse. Shoot with it off unless it's needed.

Faithfully yours.
FP

[Ozzie_Traveller]

G'day FP

There are 2 primary uses for the CPL -
a) to remove / minimise reflections from surfaces (windows, water etc), and
b) to show us the changing tones of blue sky that exist in the atmosphere

To my knowledge it has no benefit with flash

More:-
a) when you & the camera is positioned in the 30 ~ 45deg angle to a shop window (say) then you will easily see the reflection from across the road ... so by using the CPL and rotating it appropriately, you can minimise or erase that reflection.

Same with water - do as the fishermen do & see under the surface to the fish below

and
b) the colour tone of blue sky alters slightly between us looking towards / away from the sun vs looking sideways to the sun's rays. So your landscape work will show an increased blue in the sky if you are shooting sideways to the sun's rays - again, you rotate the CPL to choose how much polarising effect you want at each occasion

So- as flash is a single / small light source with (to my knowlwdge) no possible way to polarise itself, the use of a CPL will do nothing more than take away 1-1/2 to 2 stops of light from the exposure ... ie: no benefit whatsoever

There may be others here who have more info
Phil

[VTphotog]

A polarizer will increase contrast and color saturation. I believe this is the case even with flash, though I haven't done any testing in that regard. If that is the effect you are going for, it should work, even with the fill flash.
As to the flash being a small light source; the Sun is only 1/2 degree in diameter as seen from the Earth, so a flash unit could conceivably present as a larger light source.(depending on subject distance, of course)
The difficulty in using flash this way may be more due to the short duration, where one would not know the effect until after the exposure is made, necessitating multiple attempts.
As to leaving the filter on or off; my personal preference is to have nothing on the lens until I want the effect.

[DonalDuc]

Same foto with same camera, same pol filter - but different angles of pol filter

[TCav]

Originally Posted by EVAKATY75

Is there a general rule such as, shoot with it on unless you must remove it or the reverse. Shoot with it off unless it's needed.

In general, filters degrade image quality. Good filters have less impact on image quality than bad filters, but you're always better off shooting without a filter.

That is, unless the filter provides you with a result that improves image quality more than it degrades it (as may be the case with a CPL).

See http://www.lensrentals.com/blog/2011...th-bad-filters