Polarizing Filter: Circular vs. Linear ?

[Luddite Frank]

I'm making-up a shopping-list of filters for my various RF user-cameras, and would like to get some polarizers.

I see two types offered by the major mfrs, such as Tiffen, Hoya, et al:

Circular Polarizer and Linear Polarizer.


The info I've found so far suggests that the Circular Polarizers were designed primarily for Auto-focus cameras "but will work with manual-focus as well".


Is one type better-suited for use with an RF camera ?


To date, I have only used polarizers with SLR cameras, where you can see exactly the filter's effect on the image...

How does one "Set" a Polarizer when working with a rangefinder ?


Thanks...

Luddite Frank

[imajypsee]

then you need to use a linear polarizer to get a consistent polarization. I circular polarizer can be rotated to achieve a variation of the polarizing effect. On a RF camera where the view is not through the viewfinder, a rotating circular polarizer seems to be a difficult choice. You screw the filter to the lens and then you don't see what the effect really is, so the obvious choice on a RF is a linear polarizer. I use one size and buy stepping rings to adapt it to my various RF lenses. Or, I just hold the linear polarizer in front of the lens as I photograph.
Here's one I made with a Canon Glll QL17 because I couldn't make a photo with a shutter speed fo 1/500s in such bright light

http://www.pbase.com/jypsee/image/84275591.jpg

another thing you should note is that I was using the linear polarizer to cut the light; in normal use you want the polarizer and lens to be at a 90degree angle to the sun.

HTH,
Mary in Florida

[Anupam]

then you need to use a linear polarizer to get a consistent polarization. I circular polarizer can be rotated to achieve a variation of the polarizing effect.


I don't understand. The linear polarizer, too, needs to be rotated - same as circular polarizer.

The way to use polarizers with RF is to hold the polarizer up to your eye, turn it to get the desired look, note the position and then put it on the lens in the same position. Some company makes a polarizing kit with a polarizer that goes into the flash shoe but I don't know if that's worth it.

[Pherdinand]

Long answer:
circular polarizer is the same as linear but it has a half-lambda plate behind (or quarter?dunno). This makes sure the transmitted light is not linearly polarized anymore but circularly, thus the autofocus cameras do not get screwed up.
With a linear polarizer, the light passing through stays linearly polarized, which, directed towards the autofocus sensors, might lose lots of amplitude and the AF sensors will see this as a very dark scene and will not be able to focus.
Film (and digi sensor) on the other hand does NOT care how a light is polarized, only about its amplitude (and colour of course). Therefore:

Short answer:
For rf and manual focus cameras it does not matter.

hope it helps:)

[Pherdinand]

Indeed, the rotating front of the lens is problematic, and in most rf lenses this is the case (maybe all of them?). But linear does not help, since the rotation is the rottion of the polarizer together with the lens versus the scene out there.
You must focus first and then set the polarizer to keep it safe.

[seph barretto]

ok, so i need to look through the polarizer first, rotate it to get desired effect, then take note of the ring position and make sure that its the same when i put it on the RF. correct?

[Pherdinand]

yep.
not very handy to use polarizers on any camera where you can't look through the lens.

[JeffGreene]

Kenko and Photoequip both make a kit to manage circular polarizers with rangefinders. I personally prefer the photoequip solution (http://www.photoequip.net/) called FilterView. It consists of a variety of stepup rings that enable you to use a large circular polarizer with your rangefinder. The beauty of the solution is that it enables you to see the polarizing effect directly through the viewfinder. Once it's set all one had to do is make a picture. The Kenko solution consists of a viewfinder with a numeric dial. Once sets the filter through the viewfinder and then one has to dial in the correct value into the lens filter. Too much trouble as far as I'm concerned.

Leicagoodies sells the same kit for $30 more plus shipping.

Respectfully,

Jeff

[imajypsee]

But, for fixed lens use I don't mess around with trying to figure out where to put the filter to achieve any sort of effect. I just rotate and hold the filter in front of the lens (or don't rotate if there's no reason other than cutting the light).

I don't understand. The linear polarizer, too, needs to be rotated - same as circular polarizer.

The way to use polarizers with RF is to hold the polarizer up to your eye, turn it to get the desired look, note the position and then put it on the lens in the same position. Some company makes a polarizing kit with a polarizer that goes into the flash shoe but I don't know if that's worth it.

[MichaelM7]

Hi folks,

if you are into a very awkward polarizer setup, you might want to test the Kenko Polarizer System for Rangefinders, sold e.g. by Robert White, see

http://www.robertwhite.co.uk/products.asp?PT_ID=284&P=Kenko-Rangefinder-Polariser-system

It comprises a screw in polariser filter with a scale round its circumfrence, and a hotshoe mounted or hand held viewer with a corresponding scale. To find the correct polarisation position, the viewer is rotated to the desired polarisation state, and the polarizer on the lens is then turned to the same number. For lenses that turn upon focusing, you obviously need to focus prior to setting the filter.

Regarding linear or circular polarizer, there is one caveat. Some AF systems and some TTL exposure meters use a linear polarizer themselves on their sensors. As two linear polarizers turned 90° and put above each other will block all light, the exposure meter /AF will then get no light at all and thus not work. This will not happen with a circular one. I do not know, which cameras are affected, but this is the main reason why circular polarizers where invented. I don't know, if there are also digital sensors that carry a linear polarizer above each pixel.
Image effects on film are more or less the same. So, if in doubt, take a circular one.

Regards,

Michael

[FPjohn]

Hello:

The dual calibrated viewer/lens combination works for those with a more "contemplative" style.

Leitz made a swing out polarizer, the 13352, which was adjusted while in front of viewfinder and returned to the taking lens. It had a tolerable hood for 35/50mm E39 lenses.

yours
FPJ

[ruben]

The info I have due to owning a TTL OM4Ti is that a LINEAR polarizer will byass the light metering of the OM4Ti, and a CIRCULAR will not.

This doesn't mean that a LINEAR polarizer must byass the TTL metering of every camera. And this fact is in my opinion of high importance because with LINEAR polarizers you can identify the light shift cosiderably more easy than with a circular one.

On most situations you can reckognize the shift of light, but there are some situations in which it is hard - then the LINEAR polarizer may show its superiority.

Cheers,
Ruben

PS
Remember that I am unreliable for technical questions.

[MichaelM7]

Well, Ruben,

I have never looked at it this way. However, the dropout of the TTL meter is not a reliable way of determining the functioning of a polarizer for a particular picture effect. You do not know the orientation of the polarizer on the TTL meter, and it will only give you an indication, when the linear polarizer on the lens is orthogonal to the one on the TTL meter. This does not necessarily mean, that the polarizer does an effect on the image in this very same orientation.

Regards,

Michael

[ruben]

Hi Michael
I have re-written the first sentence of my message. Before re-writing it, the phrase was too broad indeed.

Cheers,\
Ruben

[bsdunek]

Linear polarizers have a much stronger effect than circular. I use linear only as I have no cameras that are affected.
Many polarizers have a mark that should point toward the sun for maximum effect. For most uses, I just aim the mark on the polarizer toward the sun, and increase my exposure 1 1/2 or 2 stops. If the setting is critical, then I look through the polarizer and determine the orientation before putting it on the lens. Admittedly very slow. This would be mostly for senic photos where things stand still.
In other cases, I use my Nikon F, the dreaded SLR, which is faster.
Kodak used to make the 'PolaScreen' which was a polarizer with an arm with at little polarizer at the end. You could look through the little one and rotate the thing to achieve the effect you wanted. I haven't seen one of these for years, even on eBay.

[Luddite Frank]

Thanks to all for the replies; very helpful to me.

I think I somehow assummed that a "circular polarizer" did not need to be "dialed-in"... ( too good to be true ! )

It would seem that using a polarizer on anything other than an SLR is a "fiddly" process...


I like to shoot at anitque car shows, so reflections / glare from glass and shiny trim is often an issue... I guess I'll plan on using my Spotmatic or Exakta for the car shows...

The photoequip / kenko systems sound interesting...

Regards,

Luddite Frank