Another Lesson on Shallow Depth-of-Field

Barn Swallow Photo by Scott Bourne

And proof that you can get shallow DOF (and) clean backgrounds using Micro Four Thirds cameras…

The barn swallow (Hirundo rustica) is an extraordinarily common bird, but its beauty isn’t in any way reduced by that fact. I love watching and photographing these birds.

Back in the days of slide film, I used to make “teaching slides.” These were photos I shot to illustrate a common photographic term or practice. Back then it cost me a quarter a piece. Now that everything is digital, once you own the camera, lens and memory card, the rest of it’s free. So I made you a teaching slide about shallow DOF.

This image was made with my Olympus OM-D E-M1X and the Olympus 300mm f/4.0 IS Pro ED M.Zuiko Digital Lens attached to the M1.4 Teleconverter for an effective focal length (EFL) of 840mm.

The image was shot hand held. ISO 640 – f/5.6 – 1/320th second.

I brought it into Luminar 4 and did a basic levels correction and crop.

If you spend time on the camera forums, the “experts” there will complain about the “crop factor” applying to depth-of-field as well as field of view. The crux of the complaint is to infer that you cannot get an out-of-focus background with Micro Four Thirds (or other crop-sensor cameras) because f/5.6 is really more like f/11.

I am not going to engage in this debate with anyone because frankly, I know what’s what and trying to explain it to folks who are fact-free is a waste of my time. But I will explain it (briefly) here. It’s a minor distraction to the point I want to make, but for those genuinely interested, here’s how it works…

As far as light pass thru goes, f/8 is f/8 f/8 is f/8 f/8 is f/8 f/8 is f/8 f/8 is f/8 f/8 is f/8! Forever. Period. Full stop. No matter the sensor size. So if you get “X” amount of light on the sensor at f/8 using a full-frame camera, (And to be clear this is the amount of light necessary to calculate the exposure, using the exposure triangle) well the very same amount of light is recorded on a crop sensor camera. So ignore anyone who claims differently. They don’t understand science. As for the DOF argument, it’s nuanced. But here goes. On my M.Zuiko 300mm f/4 IS Pro Lens, I get the very same amount of depth-of-field any other (including full frame) 300mm lens delivers. I get a 600mm field of view (FOV). I get the same DOF as a 300. That is as simple as I can make it. Now on to the point of the post.

Trust your eyes.

Barn Swallow Photo by Scott Bourne

This image fairly well illustrates that you can indeed achieve a narrow depth-of-field with a Micro Four Thirds lens. Notice the fence railing both before and after the bird. It’s out-of-focus, blurry and the area where the bird sits is sharp and IN focus.

I used no blurring tools or softening filters of any kind in post. As I said above, this is pretty much SOOC other than the few corrections I mentioned.

Remember, as subject distance to camera distance decreases, so does depth-of-field. Every time. Without exception. No matter the camera, format, lens, etc. If you get closer to your subject, every step you take will reduce depth-of-field. At f/4, f/11, f/22 even f/32. You will have less depth-of-field each time you get closer.

I was about 12 feet away from this bird when I made this picture. That’s pretty close. The image was recorded at f/5.6. The M.Zuiko 300mm lens has a maximum aperture of f/4 and when adding the 1.4 teleconverter, you get dinged a stop of light so the aperture narrows to f/5.6. In essence, this camera was shot wide open (given the lens/TC combo) at f/5.6. If this is really f/11, as the forum experts will tell you, then you might be tempted to say “wow f/11 is not gonna give me a smooth background.” TRUST YOUR EYES! Clearly it will if you are close enough.

The important thing to understand here is that your aperture setting is ONLY ONE of the factors that goes into having a clean, out-of-focus background. As I just mentioned, how close you are to your subject also impacts DOF, and greatly. In addition to the aperture and subject to camera distance, I will mention two other factors that you need to understand. The distance between the subject and the background is one factor, and the field of view is the other. The further your subject is from the background, the more out of focus it will appear. And the narrower the field of view, the narrower the depth of field.


Please do not be tricked into thinking your crop sensor camera can’t deliver an out of focus background. You have my permission to ignore the full-frame mafia.

Look at the image of the swallow. There is your proof. I do not have a special double secret camera that gives me an edge. I am bound by the same laws of physics you are. If you understand the CRAFT of photography (too many just understand – or think they understand – the gear surrounding photography) you can make great pics using a lens stopped all the way down. Just remember to get a clean, out of focus background, use a lens with a narrow field of view, put as much distance between the subject and the background as you can, use your widest aperture and get close to your subject. I hope this helps.

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