HDR Tip #3

On exporting images from Lightroom to PhotoMatix.

In the previous tip we discussed adjustments you want to make to your images in Lightroom to prepare them for the HDR process to come.

This next tips covers the step where we get the images out of Lightroom.

Lightroom is a RAW image converter (among other things).  It does RAW image conversions extremely well.  Other great RAW image converters are available to us – Capture One, Aperture, and DxO to name a just few.  These are all highly sophisticated products that do an extraordinary job.

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Creative Use of Exposure

On using f/stop and shutter speed to achieve creative results.

In the first article (All You Ever Wanted to Know about Exposure) we identified the four variables of exposure – ISO, aperture, shutter speed and light intensity and compared exposure to filling a glass of water. We can control the first three in order to respond to the fourth. In the second article (Mastering Exposure – Next Steps) we discussed how to use the histogram on a digital camera to help us get the best exposure. We looked at examples of overexposed and underexposed images. We also introduced the concept of dynamic range and took a look at some of the challenges and opportunities we enjoy when we have images that have a very low dynamic range (low contrast) and a very high dynamic range (high contrast).

You may have thought we said all there was to be said in the first two article.  Well, believe it or not there’s more  – how to use exposure creatively. We can start by talking about the four variables. Let’s not get into the last variable, light intensity, just now. Rather let’s start with aperture and shutter speed.

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Mastering Exposure – Next Steps

On using the histogram to judge the quality of the exposure. Also discusses shadow and highlight clipping, the problems the create and how to avoid them.

In the first article on exposure (All You Ever Wanted to Know about Exposure) we discussed the exposure basics, the four variables you have to work with – the intensity of the light, the ISO setting, the f-stop and the shutter speed. We made the comparison of light with water. With this analogy, getting the proper exposure is the same as filling a glass of water (or whatever).  In this article we’ll take a closer look at the kinds of challenges we face getting the best exposure.  But first let’s take a quick review.

So, to quickly review, the sensor in a digital camera or the film in a traditional camera requires a specific amount of light to produce a proper exposure. The amount of light that is required depends on the sensitivity of the digital camera sensor or the film. Sensors or film with lesser sensitivity to light requires more light while those with greater sensitivity require less light. Sensitivity is measured by the ISO number regardless of whether we are dealing with film or a sensor. Lower numbers mean lower sensitivity The numbers start at 100, possibly even 50, and increase to 400, 800, 1600 and even higher. Each time the number doubles it requires exactly half the amount of light to make a proper exposure.

Aperture, or f/stop, is the amount of light that is let through the lens. This is controlled by a diaphragm similar to the pupils of our eyes. It can open to allow more light in or close to allow less light. Apertures are measured with a strange set of numbers like f/22, f/16, f/11, f/8, f/5.6, f/4, f/2.8. The numbering system goes backwards so that higher numbers admit less light. Adjacent numbers either double of half the amount of light coming admitted through the lens. In other words, f/4 admits twice the light as f/5.6.

The only other variable then is shutter speed, or the length of time light is allowed to pass though the shutter. Shutter speed is measured in fractions of a second such as 1/30, 1/60, 1/125, 1/250, 1/500, 1/000.

We have control of three of the four variable – ISO setting, f-stop and shutter speed. These are all adjusted to respond to the fourth variable – the intensity of the light. Success as a photographer starts with getting the correct exposure and these are the three things we can manipulate to do so.

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All You Ever Wanted to Know about Exposure

On the fundamentals of exposure – the four variables that must be taken into account to achieve a well exposed image.

The most fundamental skill you need in photography is the ability to make the correct exposure. You can have the greatest ‘eye’ but if your images are not correctly exposed you will never be able to make a fine art print. In addition you will take some great photographs only to be frustrated when you try to render them as prints.

There are two exposure gremlins – over exposure overexpose_1.5and under exposure. It doesn’t matter if you’re shooting a digital or a film camera, they both are subject to the same problems. But underexpose_1.5what is constitutes an over exposed or under exposed photograph and more importantly, how can you ensure you’re getting the proper exposure?

Photography is all about light. A camera is simply a device that controls the amount of light that is allowed to shine on the sensor or the frame of film. Exposure is all about letting the right amount of light into your camera. Sounds simple? Well, there are a number of things that make this a bit more complicated, not the least of which is the terminology – f-stop, ISO settings and shutter speed.

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