topic Re: Polarizing filter for 500 f4 IS II in EF & RF Lenses

Polarizing filter for 500 f4 IS II

madencbm — Wed, 03 Aug 2016 17:11:13 GMT

I will be in rainforest of Peru taking bird pictures with the 500 f4 IS II handheld. Any opinion as to need for polarizing filter for bird shots. I have read that it is needed for landscape in rainforest.

Thanks.

Re: Polarizing filter for 500 f4 IS II

kvbarkley — Wed, 03 Aug 2016 17:53:08 GMT

It will cost you a precious stop or so in exposure, which can be an issue in a dark forest canopy, hand held.

Why not get one and try it with and without.

Re: Polarizing filter for 500 f4 IS II

Waddizzle — Wed, 03 Aug 2016 19:37:41 GMT

I suppose it would really depend upon the shot you're taking, whether or not a CPL is needed, or beneficial. At the very least, it might be a good idea to use a clear, protective filter in that environment.

Re: Polarizing filter for 500 f4 IS II

RobertTheFat — Thu, 04 Aug 2016 00:49:00 GMT

@madencbm wrote:
I will be in rainforest of Peru taking bird pictures with the 500 f4 IS II handheld. Any opinion as to need for polarizing filter for bird shots. I have read that it is needed for landscape in rainforest.

Thanks.

The two main purposes of a polarizer are to darken a sunny sky and to remove reflections in bodies of water. I can't imagine what use it would be inside a rain forest.

Re: Polarizing filter for 500 f4 IS II

ebiggs1 — Thu, 04 Aug 2016 13:39:09 GMT

I don't have and I never had a polarizer for any of my great white lenses. You do realize the big 500 uses 52mm drop in filters? Not impossible to use a polarizer but a little more tricky. Especially if you are shooting birds!

Re: Polarizing filter for 500 f4 IS II

kvbarkley — Thu, 04 Aug 2016 15:55:33 GMT

My understanding is that you get a lot of reflections off waterdrops that the polarizer can tame.

Re: Polarizing filter for 500 f4 IS II

diverhank — Fri, 05 Aug 2016 21:18:59 GMT

@kvbarkley wrote:
My understanding is that you get a lot of reflections off waterdrops that the polarizer can tame.

Not just reflections off waterdrops but any reflection so polarizer might be useful to cut glares from the forest leaves. Having said that I never bother with polarizing filter for my big white (600 f/4).

Re: Polarizing filter for 500 f4 IS II

ebiggs1 — Fri, 05 Aug 2016 22:12:33 GMT

" Having said that I never bother with polarizing filter for my big white (600 f/4)."

I never have either. You would need to guess at where to set it and if not correct take it out and trun it. Try again and perhaps several more times! If memory serves me, which it often doesn't, I don't think the ef 500mm f4 has filter threads on the front. Plus if it does, it would be a huge filter in the 130mm range and would take a boat load of gold to buy one.

Re: Polarizing filter for 500 f4 IS II

TCampbell — Wed, 10 Aug 2016 16:15:26 GMT

If you think about how a polarizer works and what it really does w.r.t. the physics of light, it's limiting which rays of light can pass through the filter depending on the polarity of the light's wave.

It turns out that whenever light strikes a surface and bounces off, the reflection fixes the polarity of the wave. The polarizing filter allows you to rotate the filter such that it's rotated to block most of the "reflected" light.

This eliminates (well.. more accurately it substantially reduces) the reflections you see on the leaves -- especially any waxy/glossy leaves.

The artistic benefit is that the leaves look "greener" because you see more of the true color of the leaf itself and less of the reflections on the waxy/glossy surface of the leaf.

It does the same with everything... glass windows, shiny surfaces of any kind (glossy floors or glossy wood paneling), and even microscopic droplets of water in the air create reflections that can filtered out (hence the sky can look "bluer").

Since the fitler is rejecting light, you're going to lose some light. How much depends on the specific polarizer and how you "tune" the polarizer. It could be less than a stop, it could be more than a stop.

As for "which" filter... there really is only one. Since the Canon 500mm has such a huge front objective lens, you can't realistically get a filter large enough for the front of these lenses (also there are no filter threads). instead, these lenses take "drop in" filters. It looks like a cartridge that slides in at the back.

This lens takes the Canon PL-C 52: http://shop.usa.canon.com/shop/en/catalog/52mm-drop-in-circular-polarizing-filter-pl-c-52

The drop-in cartridge has a tiny exposed wheel (basically a gear) and you rotate with your finger and this causes the polarizer inside to rotate -- this allows you to tune it. I have one of these for my 300mm f/2.8 lens.

I took mine outside and metered (using my Sekonic incident meter) with and without the filter. You're going to lose about 1.3 stops of light with the filter.

Re: Polarizing filter for 500 f4 IS II

RobertTheFat — Wed, 10 Aug 2016 16:35:15 GMT

@TCampbell wrote:

I took [my 500mm f/4] outside and metered (using my Sekonic incident meter) with and without the filter. You're going to lose about 1.3 stops of light with the filter.

If you're measuring incident light, what difference does the presence or absence of a filter make?

Re: Polarizing filter for 500 f4 IS II

TCampbell — Wed, 10 Aug 2016 17:14:57 GMT

With the dome in the "down" position I let it meter the full-sun sky with no filter.

Then I place the filter (just the filter -- no lens) on top of the light meter's sensor so that anything making it into the light meter had to pass through the filter first. This gives me a reading which is roughly 1 and 1/3rd stops less light.

This makes sense consider that light leaving the sun has random polarity (if it hasn't bounced off any surfaces... and it hasn't)

That means that the tolerance of the filter is accepting light with a polarity which is within roughly 15-16% +/- of the tuned polarity of the filter (since it's +/- you get to add them up and this means roughly 66% of the light is blocked and roughly 33% of the light will pass.)

Re: Polarizing filter for 500 f4 IS II

TTMartin — Wed, 10 Aug 2016 19:15:06 GMT

@Waddizzle wrote:
I suppose it would really depend upon the shot you're taking, whether or not a CPL is needed, or beneficial. At the very least, it might be a good idea to use a clear, protective filter in that environment.

The EF 500mm f/4 uses drop in filters. A clear protective filter would do nothing productive.