White Pixelation Dots

[Duane Egan]

This is a new topic (post). I saw a similar issue on the post "picture question" by 126andy and commented there but decided to start a new thread.

The attached photo below shows many pixelated type dots in the water, mainly lower left portion of photo. These can be seen when printed. Does anyone know what causes this or has seen this in other photos. I originally thought they were caused by my recent 5D MKII firmware 2.0.4 upgrade but in looking back at other photos from last year I see similar white dots but less frequent. Unfortunately this reduced size photo (100 kb) does not do justice to the dots.

I spoke to Canon EOS Tech Support and they said they were reflections and gave me some "attitude". They suggested I send the camera into the Canon Service Center.

I read Bob Atkins "Canon EOS 5D MkII "Black Dots" problem" from 2009 and this seems to be a similar magnitude of problem that Canon fixed with a firmware upgrade. I think this is a problem but Canon doesn't think so.

Any thoughts?

Thanks, Duane

[Bob Atkins]

I suspect that Canon may be correct and these white dots are specular reflections off the water. It's hard to tell from the fairly small compressed image.

Maybe you could post a crop from the full size image which has the dots in it. It might make it more obvious what their origin is.

If you're only seeing them on water it would add strength to the theory that they are just reflections.

[Duane Egan]

Bob, here are two more cropped photos, second in Reply post to follow.

Duane

[Duane Egan]

Second cropped photo

[Bob Atkins]

From those I still think they are specular highlights caused by reflection of the sun/sky from the tops of small ripples in the water

[Duane Egan]

Bob - I see what you are saying and that would be conventional thought. I've found another photo from last summer that is more pronounced. I've also found this effect in some photos from my other cameras, i.e., Canon 30D and Powershot A620, will check the D60 tomorrow. I'm pretty sure that film wouldn't show this and I know the human eye does not.
 
Anyway, I think I am going to have to live with this in digital for now. Your explaination and logic of the "black dot" problem leads me to think there is a more technical reason for what I am seeing, maybe something like photo sensor overload and/or crosstalk.

Thanks for the thoughts.

Duane

[whizkid]

I don't see how the interpetation can be anything other than specular highlights. Looking closely not only are the dots of brigntness confined to the water and the water's edge they are mostly attached to a ripple (seen as a darker line ).  The obvious rippling water and the specular highlights seems natural even desireable to portray the breaking surface tension of the water. I believe you are chasing a ghost and not a flaw. I currently shoot with both a 5DMkII and 7D and I think both are great. No ghosts. 

[KeithB]

I would suggest an experiment.  The next time you shoot something that does this, try exposure bracketing, or at least take another exposure 1 - 2 stops lower.  You might also try a RAW shot to see if the speckles are there, too.

[whizkid]

My version of an experiment would be to re-shoot the scene on a day when the wind produces similar rippling but when the sky is overcast.

[Duane Egan]

Thanks for the help guys. I have reconsidered my initial thought that this is a technical problem with digital cameras and simply concede that the point dots of light are probably in the nature of specular highlights, as was suggested previously. However, since I cannot see these small pixel size points of light with my naked eye but the camera can, I have a theory.
Let’s start out with the specular highlights classic example of a sphere (a tomato or pool ball) and a single source of light. The sphere reflects the source light to the observer depending on many things, such as angle (or half-angle), reflectivity of the sphere, etc.
Now let’s jump to a disco ball which has many mirrors on the sphere and many light sources around the periphery, a room perhaps. In this case, as the disco ball rotates, you will see many light beams reflecting off the mirrors on the disco ball and moving across the walls of the room. An observer sitting in one location in the room will occasionally experience a reflection passing right over his eye and will see it as a flash of light.
Now consider having only one light source in the room and the disco ball having only one mirror on its surface. Further, lets have the disco ball rotate completely at random about its center. If the observer waits long enough the disco ball single mirror will reflect the source light into his eye. This flash of light is visible to the observer because of the large size of the reflecting mirror surface and its nearness.
To the case in point, we have an observer on the shore of a lake on a sunny day. The lake is somewhat wind-blown and wave tossed. Now you take the disco ball previously discussed and turn it into a floating and reflecting sphere the size of your thumb. Toss a few thousand of these out in to the lake in front of you. These will act like the single mirror disco ball that rotated randomly from the previous paragraph. The sun will be the single light source and the floating balls will randomly reflect small beams of light in various directions. I consider these balls to be analogous to the small wave surfaces and disturbances that are occurring constantly on a wind-blown lake surface.
So, take away the floating balls and you still have the undulating wave patterns of the lake water creating these small randomly moving beams of reflected light. It is my theory that these beams of light are so low of intensity and move so quickly across the human eye that the brain cannot recognize their existence. But, if a camera shutter is open at the instant one of these beams cross the lens it would register in one or two or more image sensor photo cells and become part of the captured image. 
 I’m ok with my digital camera and can live with this bit of theory. Some people may think I should be in the lake and not taking pictures of it so let’s call it a day on this topic and move on.
Duane