# 5D Mark III - Possible Sharpness improvement using polarizer



## jcs (Apr 10, 2012)

This scene shot at 24mm with a FaderND gen 1 (works fine with the 24-105 lens) looks sharper than normal for a detailed wide angle shot: https://vimeo.com/40107424

It's not sharp, but it appears sharper than normal and requires less post sharpening (about 1/2 the amount). This example shows moire (church), which I haven't seen before with the 5D3 (well, have seen it before but very minor). More details in the vimeo description and original MOV available for download. Banding in sky likely due to using CineStyle and over-exposing the shot (could fix in post if this shot was needed using noise/grain or selective blurring with AE or Resolve).

If anyone has a FaderND (any version), Heliopan, etc., or clear linear/circular polarizers, would helpful to know if polarizers can help improve sharpness (some OLPFs use a polarizer- might be some kind of interaction with polarized light which reduces diffusion and blur).


----------



## neuroanatomist (Apr 10, 2012)

I suspect the effect is a subject increase in sharpness which results from the improved contrast a polarizer can produce in some lighting conditions.


----------



## psolberg (Apr 10, 2012)

neuroanatomist said:


> I suspect the effect is a subject increase in sharpness which results from the improved contrast a polarizer can produce in some lighting conditions.



that's what I'm thinking too. the polarizer will also remove reflections which can create more contrasty textures that are washed out by reflections. 

the only way to improve the resolution on the 5D seems to be to remove the OLP filter as discussed over EOSHD. this means no firmware update will improve the resolution of the 5DmkIII in any meaningful way.


----------



## LetTheRightLensIn (Apr 11, 2012)

jcs said:


> This scene shot at 24mm with a FaderND gen 1 (works fine with the 24-105 lens) looks sharper than normal for a detailed wide angle shot: https://vimeo.com/40107424
> 
> It's not sharp, but it appears sharper than normal and requires less post sharpening (about 1/2 the amount). This example shows moire (church), which I haven't seen before with the 5D3 (well, have seen it before but very minor). More details in the vimeo description and original MOV available for download. Banding in sky likely due to using CineStyle and over-exposing the shot (could fix in post if this shot was needed using noise/grain or selective blurring with AE or Resolve).
> 
> If anyone has a FaderND (any version), Heliopan, etc., or clear linear/circular polarizers, would helpful to know if polarizers can help improve sharpness (some OLPFs use a polarizer- might be some kind of interaction with polarized light which reduces diffusion and blur).



perhaps the way it was shot, or the polarizer's added contrast, gave the micro-details enough bite for the codec and/or NR to not wash details away? OTOH the over-exposure and cinestyle are counter to that, so it's a bit odd.

aliasing on the church might be the fact you happened to exactly hit focusing the exact way to produce it the time you shot with the polarize??

whatever the case, something here does seem a bit more encouraging in that the distant bushes and the grass don't seem so plasticky, like they retained more fine, organic detail

for all the talk about cinestyle, my feeling was it made some things so flat, at least with 5D2, that details would blend away banding and noise were easier to bring up in post, didn't mess around with it too much though


----------



## LetTheRightLensIn (Apr 11, 2012)

psolberg said:


> neuroanatomist said:
> 
> 
> > I suspect the effect is a subject increase in sharpness which results from the improved contrast a polarizer can produce in some lighting conditions.
> ...



I still think firmware might be able to change it.

1. I bet they add some AA in software to help the fact that the AA filter (the hardware one) is designed for 1x1 blocks for stills but they are combining 3x3 blocks and they might be able to adjust it to trade aliasing vs detail (I'd suggest user choice, since you don't want them to go dial in detail but then make lots of aliasing and maybe get it wrong and make it not crazy sharp and yet not able to take sharpening either,etc.(

2. More importantly, I wonder if a 2x2 sampled 1.6x crop mode video wouldn't end up sharper since it's closer to the native AA filter and they might not need to smooth it nearly as much. Cropped mode 1920x1080 would be useful anyway for wildlife stuff.

?


----------



## jcs (Apr 11, 2012)

If there is any real effect, I think it involves the polarizer.

Testing a linear polarizer (in addition to circular), at different angles would also be interesting. Check this out: http://nikonusa.com/en_US/IMG/Images/Learn-And-Explore/2012/Camera-Technology/D-SLR-Series/Moire-D800-D800E/Media/OLPF_schematic.pdf
A polarizer might stop/reduce/change the last diffusion stage (if the 5D3 works similarly). A collimator might also have interesting properties: http://en.wikipedia.org/wiki/Collimator (check out the Söller collimator drawing):






Ah, interesting, another clue from the Nikon link:


> By converting polarized light into circularly polarized light with the wave plate, two points are divided into four points at low-pass filter 2.



Since a circular polarizer is a linear polarizer with a 1/4 wave retarder (phase shifter, "wave plate"), curious if this might explain a real effect when a circular polarizer is placed in front of this optical assembly. Intuitively, based on testing, it could be a circular polarizer reduces the effect of the OLPF by 1/2 to 1/4.


----------

