Filter Order

[tgtaylor]

It's been so long since I used multiple filters on a lens that I forgot the proper order. With respect to the lens, which order is the best for a polarizer and color correction (e.g., 81B)

a. Polarizer next to the lens, 81B on the outside?
b. 81B next to the lens and polarizer on the outside.

What about for this scenario:

a. Infrared filter next to the lens and distorting filter on the outside?
b. Distorting filter next to the lens and IR filter to the outside?

Finally, what would be the proper order if a ND filter was included in each of the foregoing scenarios?

Thomas

[Halford]

Hi,

In your first scenario, the polariser should be on the outside (furthest form the lens). The reason is that you don't really know what your 81B is doing to the polarisation of light that strikes it -- optical elements can rotate or otherwise juggle polarisation without affecting image quality. That means that the polarisation information could be lost or messed up after passing through an extraneous filter.

So the polariser should be the first optical element that light from the scene strikes. Once it has filtered out the unwanted planes of polarisation, then really you don't care whether any other elements bend, twist or juggle the polarisation of the remaining light.

In the second scenario, I don't really know. Maybe someone else does. I shouldn't think it makes very much difference but could be wrong.

Enjoy :)
Hal

[Mark Woods]

The only time I've paid attention to the order of the filters is when I used an Arri Varicon -- it has to be the last filter before the lens. The rest are pretty arbitrary since they each affect the image. On a personal note, I usually put the diffusion (or grads) as close to the front (away from the front element) as possible to throw them out of focus. YMMV

Mark

[Mark Woods]

Re: the Polariser, with the matte boxes I've used, there was a 138mm round slot just in front of the lens, that's where the poliriser went, or the 85 Pola. Since it need to be rotated, it made sense to use it there and not in one of the rectangular slots. I'm not alone in this practice among Cinematographers.

[dave_whatever]

Lee system: polariser goes on the outside, furthest from the lens
Cokin P system: polariser goes on the inside, next to the lens

So if there is a difference, the manufacturers aren't in agreement on it. Personally I've done both and don't recall any difference in the end result.

[Leigh]

It's generally best to put the filter with the highest density closest to the subject.

This reduces the amount of light bouncing around between surfaces in the stack.

Please note that this comment refers to real glass filters, not flimsies.

- Leigh

[Heroique]

Lee is emphatic about the order of polarisers and polyester filters.

They put a sticker on my polyester filter boxes that says:


Please note: Polyester Camera Filters MUST NOT be placed between Polariser filter and the subject.

The wording is a bit confusing, and begs to be read twice or thrice. The upshot is place the polariser furthest from the lens.

Don’t think I’d want the wordsmiths at Lee to try to explain why, but I trust they know.

[Mark Woods]

I only use glass filters. The Lee warning comes from their R&D. But, as you all know, manufacturers sometimes don't get it right.

[tgtaylor]

Thanks for the input everyone. Except for the IR filter which is resin, the rest are glass.

Thomas

[Eric James]

I asked a related question a few years back on photo.net. Michael Briggs provided reasoning for placing polarizing filters closest to the subject when using resin filters. Alan Davenport provided additional justification for using GND filters closest to the lens. Perhaps Leigh has the the best answer to address your filters Thomas.

http://photo.net/large-format-photography-forum/00PWQ4

[Mark Stahlke]

I see to remember the reason for putting the polarizer on the subject end of a stack of filters is to prevent the polarizer creating rainbow colored distortion from the stresses in plastic or polyester filters, i.e. inadvertent cross-polarization.

Do I recall correctly? Would the location of the polarizer make any difference?

[tgtaylor]

I recall reading in one of the photography magazines that by placing the polarizer in the wrong position in relation to a warming filter (e.g., 81B), you lose 75% of the benefit of the polarizer.

Thomas

[ridax]

It's generally best to put the filter with the highest density closest to the subject. This reduces the amount of light bouncing around between surfaces in the stack.

I don't think this has any effect. It's the percentage of the light scattered that matters, not the total amount. The percentage does not change with the total amount reduction.

On the contrary, a dense filter can reduce the flare if put somewhere in the middle of the optical system - acting like an antigalation layer in film. As the stray light usually comes through the filter at steeper angles then the image-forming light, the stray light travels more distance through the filter and gets absorbed stronger. That is especially the case with gray filters and some others (e.g. green and color conversion ones) that have noticeable absorption all over the spectrum. With sharp-cut filters like most of the anti-UV - yellow - orange - red - IR ones, the picture may gain close to nothing from the filter being in the middle of the system no matter how dense the filter is.

Scattering between the flat surfaces is usually the worst for the image (the light reflected from a curved lens surface has more chances to leave the system), so when there are two other filters in use, I prefer to put the gray/green/etc. filter between the lighter colored or sharp-cutting ones.

That's if the quality of all the filters in use is about the same. But when some of those are coated and others are not, an uncoated one goes in front of the rest - to get part of the light reflected from it just going outside.

Also, the vast majority of glass filters fluorescent. Most (but not all) of the UV-absorbing and ALL the yellow, orange and red ones are among those, regardless of the manufacturer. Some blue ones for bw work are, too. (The green and the gray filters and the bluish color conversion ones aren't.) To minimize flare, those are better put behind a good lens hood or even on the back of the lens to avoid any excessive light falling on them. But totally avoiding such filters is definitely a better policy. Kodak Wratten gels cemented between two pieces of glass (that are called Tiffen filters on the market) are pretty free from the fluorescence problem.