June 11, 2012
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Before digital became the medium by which we made photographs the control of colour temperature was something that only professional photographers considered seriously. We had colour temperature meters that would read the colour of the light, not the brightness. From that we could deduce the colour correction filters we needed to adjust the colour of light to match the film we were using. Since the advent of digital cameras we use the White Balance controls to manage colour temperature. This article on the Lightstalking site By Jason Row explains this process
“Lord Kelvin, AKA William Thomson has a lot to answer for. It was this Glasgow University based physicist that developed the scale of measuring temperature that we use in photography today. So why does a scale of temperature have relevance in photography? Well the Kelvin scale also measures the colour of light. The science of this is somewhat complicated but put in it’s simplest terms, if you have a pure black radiating object and heat it up until it is glowing, when the temperature is below 4000K it will appear reddish, above 7500K it will seem bluish.
So why is this important to us photographers?
Well, light at different times of the day and under different conditions will have different colours. Our eyes are so highly developed that we do not see this change, our brain quickly adapts to the difference but colour film and more recently digital sensors cannot adapt.
In terms of film, it can only be set to one color temperature, usually 5500K which is the average colour of the shade on a sunny day at noon, or, 3200K which is the temperature of tungsten light, for example the average household light bulb or professional photoflood studio lights. Digital sensors can be set to a range of colour temperatures but rely on one of two things to get the right white balance – the camera’s metering system or the user setting it manually.
Neither of these are entirely infallible so if we can understand a little of what the colour of the light is in a given scene, we can improve the colour rendition of our images.”.….MORE
February 13, 2012
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“Some of you may have heard this term before, some not, but for everyone, it’s a great tip for optimizing the quality of the image coming from your sensor. So to understand how to shoot to the right, first we need to understand the camera’s histogram.
Virtually all DSLRs and many higher-level compacts have what’s known as a histogram display. A histogram is basically a graph showing the distribution of light in your images, from the shadows to the highlights. The left side of the graph represents the darkest shadows in the image whilst the right side represents the brightest highlights. A good exposure is one that keeps all that information within the confines of the graph. If the graph is sliding off the scale to the left, you are losing shadow detail, conversely if it is sliding off to the right you are “blowing” the highlights.” This article by Jason Row on Lightstalking gives a very simple explanation of the use of the histogram. I suggest you read all of the article here
August 22, 2011
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As Mike Panic says in this article on Lightstalking, PS is a program that can confuse and irritate because of the scope of it’s options. These 8 basics are some that you should know about. I think some consideration of density controls like levels and colour controls like colour balance would be the 2 that would make it up to 10 basic things.
“Despite the name, Photoshop was created more for graphic designers, not photographers, but photographers looking to airbrush their digital files quickly adopted it as their go-to piece of software. By the time v7 came out, specific tools, plugins and actions were being created for photographers and Photoshop could handle the RAW, or unprocessed files from digital cameras.
Anyone who’s opened up Photoshop knows it’s not exactly a straight forward application – it does take some knowledge to be proficient in it and productive. All that aside, here’s a few tips that all photographers should know how to do in Photoshop.”
August 18, 2011
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I want to drive you over to the ever impressive Lightstalking site today for this very useful and well written article about local adjustments. Lightstalking has many tutorials and galleries worth investigating so after you get there have a good look around. This article is By Jacob Maentz
“A powerful post-processing technique I use for almost every photo is adjusting my settings locally. I use this technique to bring emphasis to key areas of a photo that I want my viewer to focus on. I am using Adobe’s Lightroom Adjustment Brush and Adobe’s Photoshop Dodging and Burning tools to accomplish this.
I generally shoot in RAW so images right out of the camera are typically flat and dull. I first make general adjustments to my photos such as correcting for white balance and overall exposure. Then I will start making the important local adjustments. When using Lightroom’s Adjustment brush I can make the following local adjustments: Exposure, Brightness, Contrast, Saturation, Clarity, Sharpness and Color. Depending on the photo I may use all of these or only one. I use the Exposure, Clarity and Contrast adjustments most frequently. In Photoshop the only local adjustments I make are dodging and burning. These techniques can also be made with other file types, but I prefer uncompressed RAW files”…..more
March 31, 2011
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Some people are so clever, this tutorial is really great, such a simple idea as a way to get accurate colour balance, the only requirement is that somewhere in your image there must be something that is 50% grey so not much good with a red rose.
“Neutralizing a color cast can be one of the most difficult jobs in post-production. The problem I most often have is realizing that my image has a color cast, but not being able to identify which color is causing the cast! Is it magenta or red? Blue or cyan?
This simple tutorial solves this problem by finding neutral gray in the image, thereby removing the need to guess the color. In order for this trick to work however, your image MUST contain 50% gray tone somewhere in the image; otherwise the color correction will be off.”
November 30, 2010
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So Oxford finally has a dusting of snow, not the knee deep stuff our good friend and photographer Norman McBeath has reported from Edinburgh but even so snow. Every time it snows in the UK photographers are compelled to go out and photograph it, once snow was a rarity but now it seems a too frequent occurrence. Well that is my take on the stuff. Here are a series of tutorials you might like to look at before stepping out into the cold, they may make your intrepid adventure more rewardinging.
Why Is The Snow In My Pictures Blue – a tutorial about white balance
This is from Canon and is about metering- and although aimed at Canon users is very informative
Snow Photography in Japan – slightly more technical and with details of equipment recommended
5 Tips, simple and untechnical – for those who don’t like to read much
If you need more search photographing in the snow, there are lots more tutorials although they cover much of the same ground as the above. Stay warm, stay safe. I will be staying indoors.