Circular polarizer issue with 5D MKII, B + W, 16-35mm

Punkybeth

Not sure if it's me or what...but I just got back from my vacation in Sedona, AZ and I found it really hard to get an evenly "polarized" shot using my 5D, B + W CPF, and my 16-35 mm 2.8. When I rotated it, it would make only a quarter of the sky in the image more blue. I thought it was me....so I played with the rotation a little more and did a few test shots and still...I got wonky blue skies. Sorry I don't have an image to share now, but I could post one later....just thought I'd see if anyone else had this problem. Never had this issue with the 20D. Hmmmm...:dunno

pathfinder

Its not a defect, it is a feature.

You cannot use polarizing filters on ultra wide angle lenses, due to the different variation in polarizing effect from the angle of view of the lens. In short, what you see with lenses wider than about 28mm on a full frame SLR, is strong darkening, vignetting in the corners.

The solution is to avoid a polarizing filter with ultra wide angle lenses, which on a FF body is about 24-28mm. You would see the same phenomenon on a 20D with a 10-22mm lens.

On 20D, your 16-35mm lens is effectively 1.6x 16 = 25.5mm which is why you haven't noticed it with the 20D. Another way to think about it, is the the image circle captured by the 20D does not begin to be as large as the image circle with the 5D. so you do not notice the vignetting in the corners of the frame that is apparent with the 5D.

Punkybeth

Thanks Pathfinder! I knew there had to be a "technical" explanation for it...I will know better for next time. Oh well...that just means I'll need to plan another trip to Sedona for a re-shoot!

So, do you think I am better off not having the polarizer on the lens in the first place? Or just not shoot as wide? What is one to do?

pathfinder wrote: »

Its not a defect, it is a feature.

You cannot use polarizing filters on ultra wide angle lenses, due to the different variation in polarizing effect from the angle of view of the lens. It short, what you see with lenses wider than about 28mm on a full frame SLR, is strong darkening, vignetting in the corners.

The solution is to avoid a polarizing filter with ultra wide angle lenses, which on a FF body is about 24-28mm. You would see the same phenomenon on a 20D with a 10-22mm lens.

On 20D, your 16-35mm lens is effectively 1.6x 16 = 25.5mm which is why you haven't noticed it with the 20D. Another way to think about it, is the the image circle captured by the 20D does not begin to be as large as the image circle with the 5D. so you do not notice the vignetting in the corners of the frame that is apparent with the 5D.

pathfinder

Just make sure to limit your polarized shots of the sky to 28mm or longer and you should be fine. Or just dial up your Clarity in LR.

Polarizers are great for reducing reflections from glass, water, vegetation, though.

Punkybeth

Soooo...you'd think I'd learn after my initial 2010 post re: circular polarizers and wide angle lenses!!!! I forgot about 28mm rule and used it on my 24 - 70 during my recent trip to Utah/AZ. All my pics of White Pocket and the rest of my adventures came out like crap! See for yourself! I'm bummed! :bash

ziggy53

While it's a fair amount of work, you can use Photoshop to correct, or at least even out, uneven blue skies when you used a polarizing filter and a wide-angle or super-wide-angle lens.

Using Photoshop with appropriate selection, masking, layers, gradient and blending technique you can create a pretty convincing blue sky. Skies with clouds require a couple extra steps. I couldn't find any single tutorial, but Google/blekko for "photoshop correction of uneven blue skies polarizer" (without the quotes) to get you started.

For more help with Photoshop, peruse our "Tutorials" forum (especially the [thread=198464]Tutorials Indices[/thread] thread), then search the "Technique" for help with Photoshop methodology, asking for help in that forum as you need.

Punkybeth

Thanks Ziggy! I will try searching for some tutorials and see if I can work it out. But maybe I should just book another trip, instead! Wouldn't that be nice!

ziggy53 wrote: »

While it's a fair amount of work, you can use Photoshop to correct, or at least even out, uneven blue skies when you used a polarizing filter and a wide-angle or super-wide-angle lens.

Using Photoshop with appropriate selection, masking, layers, gradient and blending technique you can create a pretty convincing blue sky. Skies with clouds require a couple extra steps. I couldn't find any single tutorial, but Google/blekko for "photoshop correction of uneven blue skies polarizer" (without the quotes) to get you started.

For more help with Photoshop, peruse our "Tutorials" forum (especially the [thread=198464]Tutorials Indices[/thread] thread), then search the "Technique" for help with Photoshop methodology, asking for help in that forum as you need.

ziggy53

Punkybeth wrote: »

Thanks Ziggy! I will try searching for some tutorials and see if I can work it out. But maybe I should just book another trip, instead! Wouldn't that be nice!

Gary752

NIK Vivesa (now owned by Google) could possibly save those photos. I've used it on occasion to make a sky a darker blue without it affecting the other colors in the photo. Check out http://www.google.com/nikcollection/products/viveza/ At the bottom of the page is a link to some tutorials on how to use the program. Hope this helps!

GaryB