Reflections being Lighter than the subject

I am in the middle of a discussion elsewhere, where a poster has posted a picture of a Yosemite Waterfall - and as you can see the reflection appear to be brighter than the actual subject (worst case in some places the same brightness).

The photographer claims only a ND+CPL combination was used and no post processing (as in trickery) was used.

I know for a fact that ND Filter cannot do this, but is it possible for the Reflections to be lighter than the subject when a CPL is used ? If so, under what conditions does this happen ?

Any pointers will be appreciated.

Perhaps a Graduated ND filter was used, not a ND filter.

I agree with Allen. It appears a graduated ND filter was used.along with some post processing ( I can't be sure of that, though). If a polarizer was used, the reflection would be darker because the intensity of it would be reduced.

--P

I can think of a couple of possibilities that might make this possible. The first is that if it's a long exposure and the water is moving, sometimes the water will reflect the clouds or surroundings (the waters angle will change as small ripples pass over it). So most of the time the water is reflecting like a flat mirror but occasionally it is reflecting other parts of the scene, possibly even the sky. Averaged out, this would make the darker areas of the reflection lighter and potentially add something very similar to a 'haze' over the reflection. Also, if the light reflected from the background scene is being polarised, it's quite possible that the reflection isn't being polarised as when reflected we get a 90 degree flip in polarised light. I don't know enough physics to work this out. My gut feeling says grad but when I look along the edge of the lake, the reflection is consistently brighter along that whole strip and a grad couldn't do that... so my answer is "I dunno but I'd give him the benefit of the doubt.

I've heard this explained in another way that makes sense and requires no doubting of the photographer's statement that only a ND  and CPL combination was used and that there was no post-processing "trickery" involved. 

The subject highlights may, indeed, have been dense aggregates of specular highlights, and the brightest reflections thereof are reflections of those dense specular highlights.  The CPL can be used...and is used...to reduce or eliminate specular highlights from any scene, but would not be expected to have an equal effect on reflections of those same polarized specular highlights from a reflecting surface in a different plane.  Voila...reflections from the water's surface, being in a plane different from that of the subjects specular highlights, can, by the CPL, be rendered brighter...or darker... than the original specular brightness.

Dave Graham
East River, SD

I probably shoot more landscapes on the water than on land, and I have lots of images of reflections that appear brighter than the actual subject with no postprocessing, often using a circular polarizer, too. It happens when there is a slight mist on the water, and occasionally when there is a fine ripple on the water surface. This is more pronounced when there is more light on the water than on the land forms, due to clouds or other shadows. A polarizer can make this even more complex, with reflections looking darker in some parts of the water than others (just as a polarizer causes unequal effects in different parts of the sky).

Hard to tell exacactly what's going on in somebody else's image, because a subtle mist can be hard to detect, but when light hits the water from different directions, and the water is anything other than an absolutely perftectly smooth mirror, I am never surprized to see reflections that appear brighter than the object reflected. Any disturbance or interference on or above the surface of the water will produce reflections from the sky, the Sun, or objects other than the "subject" that you are interested in. Reflections are often not as simple as simple "rules" would lead you to believe.

Sorry, Tim,
I hadn't seen your reply before I posed mine, or I'd have acknowledged that our points were essentially identical, just expressed sightly differently.
I was just a Johnny-come-lately!
Dave Graham

I was interrupted while typing, so I did not see David's comment first. That certainly explains a lot of what I see when using a polarizer, and goes right along with my comment about how a polarizer can make things even more complex. I continue to learn. Good thread.

UPDATE: I'll echo David's last comment, too. I missed both Tim's and David's while typing, talking and eating.

Reflections are affected by a number of factors, with or without a polarizer.

Thanks everyone for the very insightful comments. Much appreciated. The photographer informed me this was shot between 3 and 5 PM (he does not recall the exact time) so I reckon it might not be the mist but other factors already highlighted that might have created this effect.

I'm gonna vote that the photographer is telling the truth. I've seen the same thing happen with CPL's many times.

Heck, when you get your shooting angle and the orientation of the CPL right you can turn a brown river blue by "encouraging" sky reflections. It's one of my favorite tricks around murky western rivers in the desert.

Based upon the explanations given, I concede that the image was made as stated. Honestly, I have not seen this effect before. Interesting.

--P

Sounds fishy to me.

I can certainly relate to what Wayne says as I have had exactly the same thing happen. See above