Polarizing filter for 500 f4 IS II

[madencbm]

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.

[kvbarkley]

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.

[Waddizzle]

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.

[TTMartin]

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@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.

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

[RobertTheFat]

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@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.

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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.

[kvbarkley]

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

[diverhank]

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@kvbarkley wrote:

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

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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).

[ebiggs1]

" 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.

[ebiggs1]

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!

[TCampbell]

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.