histograms

[Don Burkett]

By the way this Cambridge in Colour website is an excellent resource.


Kyle
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It is a very worthy read. Be prepared for disappoint though, becasue when you are done you're going to wish there was more.


He did an excellant job on a number of subjects that helped me understand a number of things much clearer.


Good recomendation Kyle.

[Kyle Webb]

Don,


<span style="font-size: 9pt; color: black; font-family: Verdana;"]As an Opto-Mechanical Engineer I use this <st1:city w:st="on"]<st1lace w:st="on"]Cambridge</st1lace></st1:city> in Colour website recourse all the time. It is an especially good reference source for technical reports and presentation in explaining optical phenomenon related to digital photography as well as optical phenomenon in general. The beauty of it is that they explain theory and show practical applications and results of the phenomenon. I am glad that you can appreciate it.


<span style="font-size: 9pt; color: black; font-family: Verdana;"]Kyle<o></o>

[Steve Eisenberg]

I like to understand more about this...


I think I understand the post processing white balance part as the card become the neutral gray target to balance against but I'm not sure how or why you are using the card relative to setting the exposure.





Thanks in advance for the help...
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For the extremes (white and black), the meter will over-compensate due to the extreme reflectance of light for white, and the lack therof for black. The meter has a benchmark expectation of 18% reflectance. So if white relects more than that, you will have an underexposure, and if black relects less, you will get an overexposure.


Here's an example where the first photo is the "correct" exposure, and the second is "overexposed" by one stop:


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[Flish]

Ok that makes sense but I think I need help understanding whatconstitutes (histograms excluded)proper exposure.


Your examples seem to show the main subject with significant detail differences. In the first, the background seems natural to my eye and the subject seems to lack detail whereas in the second example the opposite appears to be the case. Shouldn't correct exposure be when the intended subject detail reaches your desired expectation?





I'm not sure if my question even makes sense but what the heck...can't hurt too much to ask.

[Don Burkett]

Now you're getting into territory where one could argue that correct exposure is the one that produces a result you are pleased with. []


A techical step above that, the correct exposure is one where the colors, hue, tone, saturation all reproduce what your eye saw when you took the picture. The use of a grey card in trickly lighting situations can help you adjust your photos in post processing as you use that white balance to apply to your other shots. Many people are happy with a result that is not a true reproduction of the original scene. In fact, many people adjust exposures to affect a particular emotion or feeling. In other applications (documentaries, product photos, etc.) it's critical to exactly reproduce the original scene.

[Steve Eisenberg]

Ok that makes sense but I think I need help understanding whatconstitutes (histograms excluded)proper exposure.


Your examples seem to show the main subject with significant detail differences. In the first, the background seems natural to my eye and the subject seems to lack detail whereas in the second example the opposite appears to be the case. Shouldn't correct exposure be when the intended subject detail reaches your desired expectation?





I'm not sure if my question even makes sense but what the heck...can't hurt too much to ask.
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Interesting. I guess having taken the picture, I would be the only one to know how the background looked in real life. You may think it's supposed to be brownish burlap, when in reality it is bleached. I suppose the most important thing is the subject matter, and if the only way to make the subject appear correctly is to sacrifice the background, maybe that's just the way it is.


There are numerous other ways to take the same photo. A large aperture, with the flash and a high shutter speed would make the texture fade into the background, etc. But, my main point with the images was to show the camera's view vs. real life. In this case, the second photo is closer to reality, and I should have mentioned that...


But back to the ultimate question. It's all subjective. If you are trying to please yourself alone, then the answer is yes. But if you are trying to please others, and strangers at that, you start getting into the deeper question: What is art? In my opinion, a piece of art is successful if it evokes something inside of the viewers. Even better, if it evokes the exact same feeling in others. And even better than that, if it's abstract and evokes the same feelings with all of the viewers!


Your question makes perfect sense, and I have thought alot about it myself. My conclusion is that there is no ideal focus, sharpness, or anything. If it looks good to you, enjoy it. Otherwise, have some friends take a look. But don't give any pre-conditions or apologies regarding the quality of the picture. Get a pure first impression. In fact, post them in the Critique forum, cause we're your friends too!

[Flish]

I suspect it's more important for me to understand first the correct way to interpretexposureand then go toward what pleases me if that my objective. I've up some pretty valuable information from this discussion and it's much appreciated. I intend to start employing a grey card aspart of my shooting workflow in hopes to better understand the entire process.


As always, thanks for youguidance.

[Flish]

Ok, that makes sense. I was beginning to wonder if I was missing some critical element in the whole process. My goal is to first understand the correct process and then explore outward from that point. I suspect I'll be asking more question that may border on the riduclous but that's just my nature I suppose.


Thanks for all your help along the way...

[Steve Eisenberg]

Ok, that makes sense. I was beginning to wonder if I was missing some critical element in the whole process. My goal is to first understand the correct process and then explore outward from that point. I suspect I'll be asking more question that may border on the riduclous but that's just my nature I suppose.


Thanks for all your help along the way...
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I think digital photography has made us all waaaaay too self-critical. When I took guitar lessons, my great teacher told me to first learn to play, then worry about reading music, music theory, and all the rest of the intellectual stuff. Please remember to have a good time, and shoot some nice pictures. You will work out the more technical aspects over time.


And ask all the questions you want!

[Tom Alicoate]

Another important point: if you shoot raw, your histogram is lying. It is based on the JPEG, which is often one, two, or even three stops over- or under-exposed relative to the true raw data. The reason for this is that the saturation, curves, space conversion, contrast, and especially white balance processing all affect the histogram, even though they don't affect the raw data.


Here's an example:


[url="http://forums.dpreview.com/forums/read.asp?forum=1037&amp;message=26905476]http://forums.dpreview.com/forums/read.asp?forum=1037&amp;message=26905476[/url]


Until manufacturers add a raw histogram feature, the only workaround is to build a custom white balance file that reverses the effect of the in-camera processing to give you a *real* histogram. Some call that a "Uni-WB". The downside is that the metadata, preview, etc. are all useless (and very green!), so you can't check an image for color tones *and* histogram at the same time.
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I have seen this before too. Usually If I bumped up contrast and saturation I would get a Histogram that was out of whack. Now I reduce the saturation and contrast to zero and the Histograms don't look as incorrect. I only use the black and whitehistogram however. There may be a better way to make this Histogram closer to true. Anybody have any ideas? I don't want to mess with the three color ones if the results are a s bad as you say.


Thanks,


Tom