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Lincoln's HDR Tutorial Part 1: Capture
This tutorial will be my attempt to download what I have learned about creating interesting HDR images. It is by no means a comprehensive or all inclusive. Take the parts you like and discard those that don't work for your particular workflow or style. I will do it in three parts: 1) Capture, 2)Combination, and 3)Post processing
Every HDR image starts with acquisition of the images to be used. There are different methods, but for the purposes of this tutorial I am going to focus on using multiple exposures to create your image.
I am also going to assume you have a DSLR because that's what I have and therefore am in no position to give advice about anything else.
Camera Setup
RAW - ALWAYS shoot RAW for HDR. It preserves detail that will be recovered in processing, detail that will be discarded and reduce your dynamic range if you shoot in JPEG.
Mode - I shoot in one of two modes. Av (Aperture Priority) allows you to set your desired aperture for depth or light control. You can then turn on AEB (Auto Exposure Bracketing). When you press the shutter, the camera will automatically select the shutter speed. My camera will only do 3 exposures when bracketing. If you shoot Nikon, you will most likely be able to bracket 5 shots. LUCKY! One more trick for AEB. Try setting your camera to bracket 3 (or 5) exposures spaced 2 stops apart. Then, after shooting the series, adjust your exposure compensation to +1 EV and shoot the bracket again. You now have 6 (or 10) exposures spaced 1 stop apart!
The other mode I shoot in is manual. This allows me to set the aperture and then manually select the shutter speed to achieve as many shots as necessary to capture the complete range in a scene. When using this method, I use the onscreen meter as a guide. Whichever method you choose, you must keep your aperture constant throughout your series.
Drive - I almost always shoot in continuous mode when shooting HDR. This mode allows you to hold the shutter down so the camera will take multiple exposures in a row. If you are using AEB, it will fire all the shots in your bracket.
ISO - If light allows and you are using a tripod, use the lowest ISO available. It will produce the least noise. The only time this will be a problem is if you are handholding, or if your longest shot exceeds the longest exposure time of your camera.
Capture
There is no hard and fast rule for how many shots to take in your series, or how far apart to space them. I typically use a minimum of three shots spaced at 1 or 2 stops apart, depending on the tonal range of the scene. This is how I determine if I have a good capture: USE YOUR HISTOGRAM! Your darkest shot (that with the fastest shutter speed) should have a histogram that peaks on the left side. Your middle exposure should peak somewhere in the middle and your lightest shot should peak on the right. I like to make sure that on the darkest shot, there are no clipped highlights, but some of the info is still close to the right side. On the lightest shot there should be no clipped shadows, but some of the info should be close the left side. When you are done with your series, you should be able to scroll through the pictures and watch the histogram move from left to right.
Notes about Handholding:
If you find yourself staring a potentially awesome HDR image in the face, but have forgotten your tripod (or, as in my case, are too lazy to set it up) don't despair! Choose Av mode, AEB, and HIGH SPEED continuous mode. Frame your picture in the viewfinder, match up one your autofocus points to a point in the scene, and press and hold down the shutter, trying to keep the autofocus point aligned with your selected point from the scene. Your camera will shoot all shots in your bracket automatically, in many cases in a fraction of a second. The miracle of image alignment in the combination process will take care of any movement that may occur, as long as it is small. (More on this in installment 2.) I have successfully shot a 7 shot, handheld bracket in manual mode, meaning I switched the shutter speed manually between shots. They all aligned perfectly in post process.
Summary:
1) Camera: Take your time and make sure it is set up properly. If you try to HDR JPEGs, you'll be disappointed.
2) Shoot Multiple Exposures - Use at least 3. Try choosing scenes that have extremely high contrast for great results. Low Contrast scene = Low Dynamic Range = Lame!
3) Watch your histogram - Ensure that your lightest image has no clipped shadows and your darkest has no clipped highlights.
4) It's OK to handhold if you are somewhat steady and your shutter speeds allow for it. The movement of the camera between exposures can be corrected in the Combination process. Just make sure your shutter speeds allow for crisp images.
Next Installment: Combination
Please feel free to submit corrections or additional questions.
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Linear Mode
