[barondla]

Fall leaves are coming soon. Anybody use a polarizing filter with their Q? Does the af/metering system need a circular to work properly?
Thanks
barondla

[pacerr]

IME, the POL works just as you'd expect it to on any camera-lens combination. I haven't found any reason to use CIR POLs as any reported degradation appears to be in the efficiency of certain AF modes which I never use. Instant review and correction would seem to satisfy any corrections needed.

I simply use a step-up ring with the same 49mm filters I've used for years with no apparent reason to change. The FOV of the 08 lens can be problematic in certain conditions but that's a known factor.

[CWRailman]

I have always used a circular polarizer because I heard that autofocus and metering was more accurate with a circular polarizer. You may want to read this dissertation.
All about Polarizers - Linear and Circular

[Marktax]

The Q7 Complete Kit and Q7 Premium Kit both came with the last Pentax-branded filter EVER -- the polarizer for the Q-lenses. I find this notable because Pentax USED TO HAVE an outstanding line of SMC-coated filters of all types. Those days are gone. They didn't even make 27mm filters for the 40mm XS lens that came with the K-01.

[keithlester]

You don't need a circular polariser with the Q. A linear polariser works perfectly. But use what you have.

[Ontarian50]

You don't need a circular polariser with the Q. A linear polariser works perfectly. But use what you have.

Yes, a linear polarizer will work just as well on a Q.

The only reason we have "circular" polarizers is for cameras that use semi-silvered, or semi-transparent surfaces that can block polarized light. The old Canon FTb needed a circular polarizer because a semi-transparent surface in the focusing screen siphoned light off to the meter cell. Spinning a regular linear polarizer on that camera (and others that used that oddball system at the time) caused the meter needle to go up and down without a change in brightness.

Since the Spotmatic at that time read directly off the focusing screen, without any semi-transparent parts, a regular "linear" polarizer worked just fine.

When autofocus came along, semi-silvered mirrors siphoned light off to the focus module in the base of the camera for AF. A linear polarizer turned the wrong way would shut off the focusing.

The solution was again the "circular" polarizer, which is really just a regular polarizer with an extra layer behind the polarizing film to re-randomize the alignment of the photons.

The unfortunate thing is the term "circular" since most of the darn things are round anyway. Perhaps in theory a linear polarizer might be of better quality since it has only one layer, not two. But all the top-grade circular polarizers I've seen work just fine.

This is a long way around stating that since the Q is simply a lens in front of a sensor, there's no semi-transparent surfaces in use. So there's no need for a circular polarizer's extra abilities, but it will work just fine all the same.

[narual]

try picking up a didymium filter. The effect is subtle but excellent for landscape, and especially for fall foliage. Use it along with a polarizing filter. Short story, it filters out a sort of nasty muddy yellow-orange color. (it's also great at filtering out light pollution for night sky shots) Dying leaves have a lot of this color mixed in with the pretty colors, and when it's filtered out, the leaves look much more vibrant.

Ideal for landscape applications, enhancing filters (Tiffen, Lee), also marketed as intensifying filters (Singh-Ray), are made from a rare-earth element (Didymium) that reduces a narrow range within the orange portion of the spectrum, resulting in moderate increases of saturation in rust-brown, orange and red-toned subjects and greater levels of saturation in crimson and scarlet-colored subjects. These unique characteristics make enhancing filters ideal for landscape applications, especially when shooting foliage, rock formations, wood structures and similar color-centric scenarios.

When using enhancing or intensifying filters it’s recommended you avoid Auto WB as its nature is to neutralize the color balance of the photo. Instead, use a pre-set WB (Sunny, Cloudy, etc. or custom unfiltered) balance in order to realize optimal results.

Enhancing filters are not recommended for portraits as they tend to exaggerate warm tones, and as such, do not enhance your portrait subjects.

Also they're funky glass that looks one color in natural light and another indoors (or at least, under CFLs), which is kind of neat and useful to know if you're expecting to see a slightly pink filter and it's slightly green instead, it's because the photo you saw of one was under a different kind of light.

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Last edited by narual; 10-13-2016 at 09:40 AM.

[pacerr]

The only reason we have "circular" polarizers . . .

A confusing topic well, and succinctly, covered. Needs to go to the Articles sub-forum as a reference resource. Older linear POLs are inexpensive and unless they give noticeably unsatisfactory results there's no reason to 'upgrade'.

[CarlG]

There is always a reason to upgrade. It may not be a perfectly logical reason, but it will be there, somewhere.