For good or bad, shallow depth of field is the attribute of a photograph that typically strikes a viewer as a quality of professional photography. It is also the subject I'm asked most about by lay photographers. I have seen many uses of shallow depth of field when it's inappropriate, and many budding photographers overuse the hell out of it once they figure out what it is, and how to produce it.
First, "depth of field" is a measure of how much of a photograph is in focus from near to far. Shallow depth of field is produced when the focus point is in focus, and that's about it, while deep depth is produced when essentially everything is in focus. It can be affected by many different things: lens aperture, lens focal length, isolation of subject from background, focal distance, and negative or sensor size.
Essentially, depth of field is at its shallowest when the subject is nearer to the camera, the aperture is set wider than say f/2.8, the lens is about 85e or longer, and the camera has a large negative size. Of these factors, one that seems to play a huge role is sensor or negative size; a large negative will always carry a shallower depth of field. This is why you can't get that background to go out of focus on your point and shoot digital camera, even with a wide open aperture. Really, if you want shallow depth of field, the simplest way to get it is to pick up a cheap 1970s mechanical film SLR with a 50mm f/1.8 lens, and go to town.
Sensor/negative size comparison chart
Aperture is important, sure, but a large negative size will prevail over a narrow aperture in many situations. My Polaroid SX-70 has an effective negative size of 3x3 inches, putting it squarely in medium format territory. Its maximum aperture is only f/8.8, but even as such it has a nice shallow depth of field in many situations:
As I mentioned earlier, shallow depth of field is easy to abuse once you know how to use it. If you want to isolate a subject from a background, it's wonderful; if you would like to take a photo of an object receding into the distance, not so much usually. It's also easy to overdo it at a certain point, where your subject is not necessarily entirely in focus, which can become distracting. You can also miss out on a lot of interesting background images if you become too obsessed with shallow depth of field. Finally, I tend to notice that modern lenses, with their ultra-sharp plane of focus, can produce rather ugly effects as focus falls off and the background becomes blurred.
Here are some of my favorites from others and myself:
(Mine - Tilted film plane adds makes the depth even shallower )
This past Wednesday was the annual Ride of Silence in North America. If you're not familiar, the Ride of Silence is a slow group ride to remember those cyclists who have been injured or killed while cycling on public roadways. If you are interested in finding a ride near you for next year, check out this link.
I took along my Polaroid SX-70 and took some of the last 600 film I have access to.
This Monday through Friday mark the spring Polaroid week on Flickr, where instant photographers post lots of incredible photos to a group pool to show how distinct and versatile that medium is. People always ask me, "What kind of camera is your favorite?" and my answer always has to be Polaroid, strange as that may seem. There are many reasons for this - my first real camera was a Polaroid SX-70, inherited from my grandfather. Also, I have many fond memories of Polaroids from my youth, when we would go fishing, or at a birthday party. When I got into film photography again, the Polaroid was there for me - easy to scan, instant results, and incredible colors.
But more than that, Polaroid made some very interesting film and cameras. The SX-70 is in my opinion the greatest camera ever made. It's an SLR that folds completely flat and is easy to carry, has a great lens that focuses down to 10 inches, and for the first time a camera developed prints before your very eyes, in daylight no less. It has the ability to amaze everyone from children to ol pro photographers. The film has that unique Polaroid look to it, with faded colors, development abnormalities, and an overall glow. There are photoshop actions that mimic it, but nothing ever gets it quite right.
So whenever Polaroid week comes around, it reminds me to shoot up the remaining film stock that I have, and to enjoy those cameras once more. The film I love is gone for good - Polaroid quite making Time-Zero, 600, 669 and all the rest a couple years ago. Thankfully I can stock up on the equivalent Fuji films for my old packfilm warhorse, and for the SX-70, the Impossible Project is doing some remarkable work bringing new filmstocks to the market. I personally can't wait to try their black and white 600 version of the new Silver Shade films. \
Here are some of my favorite Lansing-themed Polaroids:
I'm Vector Einstein, or VE for short. I drive around in a electric vehicle, or EV for short. With the help of an infinite number of monkeys, on an infinite number of typewriters, we write a little blog called "Electricity in the Motor City," or E=MC for short.