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05-05-2012, 07:41 PM   #16
jac
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Snow exposure

QuoteOriginally posted by G_Money Quote
Sorry but Jac is right, joe.penn. Metering off a white area will make the camera expose it to an 18% grey, or a Zone V as Ansel would have called it. The white area needs to be moved a couple of stops lighter i.e. by overexposing 2 stops. That would push the whites back into the highlight end, away from the mid-tones. I can remember an old rule of thumb that advised in the absence of a neutral grey card, you could meter off the palm of your hand and open up one stop. This would push your skin tone a stop lighter than neutral grey where it should be. The advise is not to overexpose or blow the detail in the highlights, but rather to move the highlight tones into the top end of the histogram and not leave them in the middle.
Very gray and overcast today so not much overall contrast in most scenes. These are straight out of the camera in RAW, exported as jpegs. No retouching of any sort as you can see by a few blotches here and there. I will often shoot three at a separation of 1 to 1.5 stops just to allow for errors in judgement on what the exposure ought to be. The K5 was set with a EV adjustment of +5 and a spread of 1.5 so these three are -1, +0.5 and +2. The histogram for the +0.5 shows that I'm a little off to the left with the highlights so I would probably adjust either brightness or exposure a tad, being careful not to blow out the detail in the snow. Ironically, I will probably bring it up to about +1 in doing this.

(And now I do regret not taking time off work yesterday morning to shoot the small male bear [eight feet nose to tail] that passed through town around 7:45. For better or worse, there was one tag left for a bear at the Hunter's and Trapper's and he suffered a fatal case of lead poisoning not long afterwards.)

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05-05-2012, 08:06 PM   #17
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ahhh zone V - I smell dektol and rapid fix again.... oppps a flashback where did my exktalure paper go?
05-05-2012, 08:11 PM   #18
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Wow quite a few different opinions...... I have an older gossen luna pro with the incident disk which I have not used in at least 30 years. I may play around with it

Thanks a ton for all the info
05-06-2012, 02:37 AM   #19
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QuoteOriginally posted by joe.penn Quote
This is wrong - there is no such thing under pentax (or any other brand of DSLR) that would automatically know what the scene is and automatically under-expose, the only possible way this could happen is if there is some kind of artificial intelligence built into the camera. ---> Unless I am miss understanding this or I missed this feature somewhere down the line <---
Don't be so quick to point out someone is wrong when you haven't thought through what you're talking about.
If you knew how a camera's exposure meter works, you'd know that it will determine exposure based on an average scene where there are roughly similar amount of darks and light. The camera's meter will be based on a given standard. Most cameras will get the exposure correct for the majority of such scenes. When shooting a scene or object where there is high subject reflectance such as snow, at the beach or an all white shirt and there is little if any proportion of dark tones, the camera's suggested meter reading will underexpose. In much the same way, shoot an all black object and the camera's suggested exposure will bias towards overexposure. I've used many different cameras over many decades to know what I'm talking about.


Last edited by creampuff; 05-06-2012 at 02:46 AM.
05-06-2012, 05:26 AM   #20
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QuoteOriginally posted by jdunie Quote
Greetings:

...Any ideas of how test test out your ideas before I go? I was thinking of a series of white/eggshell shirts against the whiteish siding of my house.
Thanks in advance
If you haven't exposed for tone before, than taking a couple shots of the side of you house will be instructive, as you'll see how the camera misinterprets the amount of available light when shooting a frame with a large portion of bright white and just how much additional exposure compensation is required to get the white correct.

I would also suggest practice once you start your trip and using bracketed exposures until you get a handle on a good compensation.

Bring a long lens and do exactly what your guide tells you to do. Wild polar bears need to be respected and distance between you and them is a good thing.
05-06-2012, 06:24 AM   #21
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Just to stick my nose where it doesn't belong, when you use the camera meter it will set the exposure of what ever it's active sensors see as a Zone 5, neutral grey. If those sensors are seeing snow, that snow will be exposed to 18%, neutral grey (Zone 5). Snow probably belongs in Zone 8 (on a reasonably bright day). You need to add 3 stops of exposure to get it there. By the nature of the camera, most Pentax meters I've used add 1 stop. That means you will probably need to dial in a +2 compensation if you're actually seeing a white bear on white snow. As someone noted previously, you will probably be seeing the bears (if you're lucky) on tundra near water, so this whole discussion might just be academic anyway. The best plan is to get there and start shooting the "typical" background immediately, then check your exposures and adjust. I'd bet the in camera meter will do just fine as is (on typical covered tundra)
In reality, I'm very jealous of your trip. If I'm lucky, someday I want to go visit Churchill in Late August, September, maybe a Halloween visit.
ENJOY the trip
05-06-2012, 07:53 AM   #22
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Calico about sums it up including the Churchill trip which is one of the few places in the circumpolar that there is a guarantee of up close and personal sightings.
Check your histogram, go with AV, add a bit of EV compensation, bracket and chimp.
And have a great time, bears or no bears! John
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