Polarizers

[Clayton Lofgren]

I have been asked about shooting some bikini-clad models posing at typical tourist locations for a local calendar. Scenery will vary from swampy grassland to mountainous jungle. I do not own a polarizing filter, but am thinking that maybe I should get one. For those who know- do you think I would see a major improvement by using one, and what should I bear in mind when choosing it?
I will be using a Tamron 28-75 2.8 with either a Sony A700 or A350. I would not expect the printing to be especially high quality.

 

[nicolas claris]

Bonsoir Clayton
I used polarizing filters some years ago, it's a bit a pia, as you have to rotate it to adjust for any change of direction toward light…
It helps to avoid certain reflection from the water or shiny surfaces as mirrors or glossy varnish/laquer…
Never complained to have left them aside!

Why are you thinking of using those fileters?

 

[Clayton Lofgren]

I would think they would improve the appearance of the background scenery, but do not know if the difference would be enough to worry about. As I understand it the circular polarizers do not need to be rotated, but I expect their effect is reduced.

 

[Doug Kerr]

Hi, Clayton,

I would think they would improve the appearance of the background scenery, but do not know if the difference would be enough to worry about. As I understand it the circular polarizers do not need to be rotated, but I expect their effect is reduced.

Not so.

Any polarizer needs to be rotated to properly "orient" its selectivity to light of different polarization to attain the effect you want.

The difference between linear and circular polarizers does not affect this. And the effect of a circular polarizer is not less than that of a linear polarizer.

Here is the difference:

In a linear polarizer, the light coming out is (linearly) polarized, which can make metering erratic in cameras using semi-reflective reflex mirrors in the metering chain. In a circular polarizer, the light coming out is circularly polarized (and thus does not have a specific axis of polarization); this avoids that problem.

Best regards,

Doug

 

[Bart_van_der_Wolf]

I have been asked about shooting some bikini-clad models posing at typical tourist locations for a local calendar. Scenery will vary from swampy grassland to mountainous jungle. I do not own a polarizing filter, but am thinking that maybe I should get one. For those who know- do you think I would see a major improvement by using one, and what should I bear in mind when choosing it?

Hi Clayton,

I make selective use of a Circular Polarizing filter. It can help to get more saturated colors on shiny/waxy surfaces. They can also be used to darken the blue of the sky (to increase the contrast with the clouds) but the effect changes with the angle towards the sun (it's maximum at 90 degrees from sun angle). That makes it a lesser candidate for wide angle lenses. Also, the 90 degree angle to the sun isn't necessarily the best angle for other objects at the same time, so you'll have to choose.

It'll slow down your shooting (not only because it absorbs more than a stop of light), unless you use it on a given scene in a single position. I may use it in a single position if most of the subjects are oriented all in the same direction towards the light (e.g. certain kinds of foliage/grass). Otherwise you'll have to continuously adjust for the desired result (which is not necessarily at maximum reflection attenuation).

Whatever you choose, it should be a "Circular" version of a Polarization filter instead of the "Linear" variety. That is necessary to prevent unpredictable lightmetering effects, and perhaps issues with the AA-filter in front of your sensor.

Cheers,
Bart

 

[Clayton Lofgren]

Thanks to all for the info. Are there any other downsides? Will a filter do anything nasty to skin tones?

 

[Bart_van_der_Wolf]

Thanks to all for the info. Are there any other downsides? Will a filter do anything nasty to skin tones?

They are supposed to be neutral, so the camera WB will react as usual. Any mild cast that there may be, is easily corrected at Raw conversion time. It will increase/restore the saturation of the skin when you suppress the skin reflections, But you might want to keep some of it a bit shiny. The only real color change is to be expected when a colored reflection is eliminated (e.g. skin will lose the blue sky or water reflection and reveal the skin color).

Another thing is that on some lenses it is hard to operate the polarizer when the hood is on. Also check that the hood can be removed with the filter mounted, some filters have a larger outer diameter than the inner diameter of the hood.

Bart