How do you make a mountain appear as large to the viewer as it does to you? How do you get rid of noise in your nightscape images? How can you get everything in perfect focus, from front to back? This might as well be titled 5 things you can’t do in one shot, since each of the following techniques relies heavily on layering multiple exposures. But these are the techniques I often use to translate my vision, and turn questions like the above into reality. Let’s go!
1. Perfect focus through focus-stacking
We’re kicking things off with a technique that originated in macro photography, which captures a sharp subject and retains a creamy background. But what if you wanted to also capture a sharp background? That’s where we shift our attention to landscape photography. With focus-stacking, you can fix everything in place throughout multiple exposures.
Using a solid tripod and shooting with a cable release will ensure the camera doesn’t move. For the best results, every setting on the camera should also be exactly the same: white balance (fixable in post when shooting RAW), shutter speed, ISO, and aperture.
The one difference is the focus distance. Start by adjusting focus to the closest object in the scene and wait for the wind to die down (if applicable). Hit the cable release and adjust to focus a little further into the scene. Repeat this process until you’ve reached infinity focus distance. You will need more exposures at shorter distance intervals when you use a larger aperture, like f/5.6.
Can we do without?
Sure. Dial in f/22 on your wide angle, set it to its hyperfocal distance and everything should be tack sharp. Right?
Well, it’s not that straightforward. Closing up the aperture has some nasty side effects. For starters, you will let less light in. At the same ISO, this will lengthen the exposure time (shutter speed). Even with the slightest breeze, delicate foreground elements like flowers, grass and ferns will for sure sway and actually make the foreground look less sharp than say, f/7.1.
Ever heard of the sweet spot of the lens? That’s the aperture at which your lens produces the least amount of aberrations, while keeping diffraction to a minimum; usually one to two stops down from wide open. At f/22 though, diffraction plays a detrimental role in the sharpness of your image.
Why is this useful?
As focus stacking will be very useful at your lens’ sweet spot, even the cheapest lens will appear to shoot razor sharp images, rivalling the single shots of the pricey contenders at smaller apertures. But because diffraction is a physical property attributed to the way light hits the sensor, even the sharpest lenses out there will not be as sharp at their minimum aperture.
2. Exposure as seen by the human eye with HDR
A more familiar exposure-blending technique is, of course, high dynamic range imagery. Whether you run Photomatix, HDR Expose or use Lightroom to blend your images together, I’m sure you’ve heard of expanding the dynamic range of your images.
Most often, the idea is that you capture a series of exposures where every setting on the camera is the same, save for the shutter speed. This theoretically makes it possible to properly expose the highlights as well as the shadows in the harshest contrasts. It’s where the name of high dynamic range imagery finds its origin: if one photo doesn’t contain all the information of either shadows or highlights, the dynamic range isn’t enough for the scene you’re trying to photograph.
In practice, just about every photographer has his or her own approach to expanding the dynamic range of any given camera. There’s the dedicated software I mentioned earlier, but there are photographers, including myself, that do it all by hand. The trick is to make a selection of exposure based on that exposure’s luminosity. You then mask out the over- and under-exposed areas to reveal the better exposures for those areas.