Experience could sometime be your biggest obstacles, especially when you are leading into new technologies, digital photography has no exception.

While we have the habit of going slight under exposure to saturate the color in film, we naturally do it the same when we gets into digital (at least I know a large number of friends who did this, the experience photographer did this and the junior photographer learned). Ignorance of how technologies works is a sin.

I did the same in the past, until the day I shoot the back stage of chinese opera when my lens is not fast enough, and my D70 doesn’t give a good result in high iso. With misunderstanding how the digital works, and misinterpreted the concept of the RAW, I choose to shoot the entire scene with under-exposure of 1.5 stop to gain more speed. My idea was, since the RAW convertor allow me to adjust the exposure by 2 stop different, I can always retouch the photo in RAW without losing the detail. You can tell how stupid I was by the result of not understanding the medium.

And I was shocked by the result because it’s so noisy that eventually I have to throw away more then half of the photos. My first thought was D70 high iso performance is extremely bad (I was shooting at 400~800), but at the same time, I felt I did something very wrong. I inspect the photos over and over again where I found out that the noise only appear in the dark area when I increase the exposure, but the brighter part is not infected.

I need an answer, I search on google for whatever keyword I can think of until several hour later I found a thread from Thomas Knoll (the original author for Adobe Photoshop and Camera Raw). Suddenly everything is explainable.

I’m not going into technical here, but the basic concept is the bright tone contain much more information then the dark area, in fact the brightest tone occupied the 50% of the information. Of course when you blow out your highlight, all the information will be gone, but you should however keep the shoot to right side of histogram (over-exposed). The S/N (Signal to Noise ratio) explained by Mr.Knoll is clearly pointed out my mistake with digital, as I know there’s many out there would do the same as me.

Read here on Luminous Landscape, the article where Michael Reichmann did an interview with Thomas knoll and the detail technical knowlegde of the S/N Ratio in digital photography. Double thumbs up for Luminous Landscape, very dedicated site for photography knowledge.

PS: I hate reading white-on-black, don’t people learn that it’s better to have the text black-on-white when you have a long article?