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What's the diff ...
  
 
RustyBug
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p.1 #1 · p.1 #1 · What's the diff ...


Same camera, same lens, same subject, same shutter speed, same aperture, same ISO, same WB, same time (okay 45 seconds apart), same ambient conditions.

Enlightening thoughts welcome.





Both @ 1/500, f/7.1, ISO 160, same WB ... 45 secs apart







100% Desat




Nov 01, 2013 at 10:23 PM
Bob Jarman
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p.1 #2 · p.1 #2 · What's the diff ...


#2 is the green channel only


Nov 01, 2013 at 11:21 PM
RustyBug
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p.1 #3 · p.1 #3 · What's the diff ...


Both left & right color are full color RGB channels.
The mono version is just a straight 100% desat.
I've got the three channels split out (intended to show), but they really didn't tell very much diff other than the change in the yellow foreground area (which is really inconsequential information).

I should have labeled them for clarity, so I'm not quite sure if you meant #2 to be the (assuming so) mono version or the right hand color version.

For further clarity, let's say that:
#1L = Color Left
#1R = Color Right
#2L = Mono Left
#2R = Mono Right



Nov 01, 2013 at 11:41 PM
Bob Jarman
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p.1 #4 · p.1 #4 · What's the diff ...


The second image posted....both panels







Nov 01, 2013 at 11:44 PM
RustyBug
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p.1 #5 · p.1 #5 · What's the diff ...


The second image posted (2L & 2R) in the OP is straight desat of the full color RGB.

Here are the full color RGB, split @ the three different R, G, B channels ... not sure if that's much help though.

I should point out (just for clarity), no pp of any kind applied to the color images of 1L & 1R (other than the straight desat to reduce it to tonal values for comparison @ 2L & 2R).





Red Channel







Green Channel







Blue Channel




Nov 01, 2013 at 11:56 PM
Bob Jarman
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p.1 #6 · p.1 #6 · What's the diff ...


Not to be stubborn or rude, but I'm afraid I am totally missing the point?

But, this reminds of something Vincent Versace goes through in his BW Conversion book, an excellent resource but not really for those (myself included) inclined to less rigorous workflows. I'm afraid I prefer 'playing' too much.



Nov 02, 2013 at 12:20 AM
RustyBug
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p.1 #7 · p.1 #7 · What's the diff ...


PM Sent ... anyone else care to take a stab at the diff (I divulged to Bob already).


Nov 02, 2013 at 12:42 AM
 

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cougaris
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p.1 #8 · p.1 #8 · What's the diff ...


Not sure if this is what you are after. Looks to me like the images were taken at different focal lengths. Although similar in size, they were taken at different distances.


Nov 02, 2013 at 03:25 AM
RustyBug
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p.1 #9 · p.1 #9 · What's the diff ...


+1 @ diff distance (same FL), not critical ... mostly looking at exposure & WB color variance, bearing in mind it is the exact same card in both left & right images.


Nov 02, 2013 at 03:46 AM
cougaris
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p.1 #10 · p.1 #10 · What's the diff ...


I'm grasping at straws, but the only thing that I can think of is that one of the images was taken with the sun behind the photographer and the other in front. With negative exposure compensation on the image on the right, would have darkened the cards but because the photographer was facing the sun, the sky is still blown out.


Nov 02, 2013 at 04:14 AM
Oregon Gal
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p.1 #11 · p.1 #11 · What's the diff ...


A shot in the dark, differences from metering off a grey card verses white card?


Nov 02, 2013 at 05:14 AM
RustyBug
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p.1 #12 · p.1 #12 · What's the diff ...


Cougaris ... well, that's a pretty good grasp.

BTW ... Welcome to FM and the PC Forum.

Nothing to fool the meter, none was used, no EC utilized ... just a straight same manual setting used for both images.

Exposure was set by "Sunny 16", which suggests that an exposure of ISO 160 would warrant an exposure of f/16 @ 1/160 shutter speed. For this time of day (5:06 PM), I mentally associated that the exposure would be reduced by 1 stop from EV 15 (Sunny 16) to EV 14. Sunset typically provides around EV 12 illumination and pre-sunset is from EV 14 - EV 12. With about 90 minutes til sunset @ 6:44, I went with only a 1 EV reduction for my exposure of the left side image, based on lighting conditions (clear sky all directions) without using any metering device in or out of the camera.

Thus, a "Sunny 11" would be f/11 @ 1/160, which I chose a combination @ 1/7.1 @ 1/500 (which is 1/3 stop less than EV 14).

The test shot was initially to assess my utilization of the Sunny 16 and EV system for exposure without relying on a meter which can be fooled by various things ... i.e. very old school, kinda like how Adams is reported to have determined exposure for Moonrise Over Hernandez without any metering devices.

Extending from that though, I realized I had a good opportunity to shoot from "the other side" of the subject to compare the lighting variance between E-W orientation. So, I turned the cards 180 degrees to face east and reshot them with the exact same exposure.

My goals for the comparison were to assess how much luminance and hue variation there is coming from different portions of the sky when receiving light from the direct warm portion of the sky vs. the indirect cool portion of the sky. These are the results side by side.

Of course, had this comparison be done at noon, the diff's would be negligible as each direction would have equal amounts of warm direct (overhead) vs. cool indirect contributions to the image from either direction. However, as the hour gets later (or earlier), our orientation to different portions of the sky continue to matter more significantly regarding our source of illumination.

At this time of day, with only a 1 EV exposure variance, we typically don't associate a color shift to the "golden hour" nearly as much as we do when we get into that last hour before sunset. Most folks know that shadows are cooler than their full lit counterparts, but I just wanted to see how much difference orientation to the sky made with the light falling on our subject.

Seeing the recent number of waterfall shots and my mention that a watch (time of day) and compass (orientation) are valuable, combined with my seemingly incessant indication of blue cast, I wanted to see how much diff there was. I shot these two images about a month ago, but had not yet taken the time to look at them side by side. The waterfall shots prompted me to do so ... the results just being shared.

Even with my indication of the diff @ warm direct vs. cool indirect for some time, the results were a little surprising to me at how stark the diff is.

Anyway, these are 180 degrees apart and while the cards are the exact same white, gray, black in each ... they don't present the same even though shot with the same exposure. No real surprise there, but in a backlit scenario, such as the shot on the right, it would be very easy for the meter to get fooled (and we learn to use EC or fill light), but with our waterfalls we really don't have the ability to fill them if they are backlit.

The two issues that I see are the exposure variance and the WB variance. I'd venture to say that most folks shoot waterfalls (and other outdoor subjects) in daylight WB when they have an open sky. But depending on the time of day and orientation to that open sky, daylight balance may not be the color or light that our subjects are actually receiving, thereby imparting those casts to a degree/fraction of that which has been imported on our white card in the right hand side.

If we look at the background sky of each image, and realize that the background sky of one image is the source of illumination for the other image (recalling that each were shot with the identical camera settings), we can see just how much difference there is in our light source of the sky depending on orientation to which portion of the sky we are receiving our light from onto our subject @ AI=AR.

The next step for me is to see how much correction needs to be applied to bring our subject on the right to have similar exposure and color as our subject on the left.

Anyway ... long and boring, but hopefully informative (or thought provoking) for comparison and a nugget of usefulness that I could finally put an illustration to what I've been speaking to. Dare I say, this is an example where picture IS worth a thousand words ... well 891 anyway.



Nov 02, 2013 at 01:50 PM
cougaris
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p.1 #13 · p.1 #13 · What's the diff ...


Thanks for the explanation. I read this the first time and thought, "what did I get myself into?!!" I've been a reading things on cameras for years and never heard of the "Sunny 16" rule. Googled it, re-read your explanation with a bit more understanding. Interesting stuff and love to learn! Thanks RustyBug.


Nov 02, 2013 at 03:52 PM





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