Landscape photographers, as a group, generally are looking for the greatest depth of field possible in their images. The intent is to emulate what the viewer would see were they standing right there, with everything from their toes to the horizon in focus. Although our eyes don’t actually work that way (we scan a scene and our brain pieces it all together in a way that makes it look like everything is in focus) it’s the way we expect a landscape scene to look so photographers work to deliver that in their final work.
In the good old days of view cameras this infinite depth of field was accomplished by tilting the lens downward a bit to expand the depth of field at the film plane (which was not tilted). From William Henry Jackson to Ansel Adams this was the way you got wide depths of field in a landscape photograph. When medium format and 35mm cameras came along with lenses fixed parallel to the film plane this wasn’t possible until the invention of tilt-shift lenses, which act somewhat the way a lens on a view camera works.
Another method has always been possible but until the invention of digital photography wasn’t easy. You could always photograph sections of a scene, each in focus, and paste them all together to create a final image where all parts are in focus. This was a very time consuming effort and the results not always satisfactory, or easily reproducible. With digital processing, though, it’s just a few clicks away.
I’ve played around with this “focus-stacking” technique a few times in macro photography as a way to bring more of a small object in focus within a single image. While at the NANPA Summit, though, I heard George Lepp talk about it as a way to expand depth of field in landscape photography as well. It’s essentially the same process – take several images of different parts of a scene, all in focus for that part – only instead of cutting and pasting prints you let Photoshop combine the digital images into one, picking the areas that are in focus to generate the final image.
Here is an image made up from 17 individual images, each one made using a different focal point. I put my camera and long lens (works best with a long lens to get the detail in the final image) on my tripod and made each image, gradually moving my focal point from right in front of my feet to the distant shoreline. I then made adjustments to the exposure for each in Lightroom and moved the whole group to Photoshop to be turned into a panoramic – a vertical one.
As you can see in the follow three crops, each part of the overall image is in focus (well, mostly – I could have made more images to make sure each section was accurately focused).
It’s true that closing down the aperture will increase depth of field but the results will most likely not be this good. First, long lenses have a narrow depth of field simply due to physics so I would not have been able to get the snow at my feet and the distant shoreline both in focus even if I closed the aperture to f/32. And using a shorter lens (which will have more depth of field at the same aperture) would not give me the distant detail I want. Second, closing down the aperture smaller than the “sweet spot” in a lens (usually in the middle of the aperture range) means lost detail due to light diffraction around the edges of the aperture blades, scattering the light as it reaches the sensor. Granted, most of this wouldn’t be noticeable unless you really zoom into the picture or print it really big, but what’s the point of capturing detail across the distance of a composition if you can’t do that!?
But what about horizontal? You can use the same technique but instead of a single row of images you’ll need to add one or more rows in order to get enough of the scene in the final image. Simply make several images in a row, point the camera up or down to a new focal point (with some overlap of the prior row), make several images in a row, etc. until you have enough rows to cover the scene. I usually then make traditional panoramics of each row of images and then the final image from combining the panoramics. Photoshop will combine either vertically or horizontally when it realizes you have overlapped enough of the scene.
Obviously this works best where nothing in your scene is moving. It’s fun, though, to be able to create images that look like the way we expect reality to appear.