Updated, September 2025

Life is full of foolish myths, ideas that get planted into our brains by rumor or gossip or misperception, and seem to endure.

One of those myths in photography is that sensor size affects depth of field. I hear it all the time in class, in the field, and, of course, on the internet.

The widely held notion is that larger imaging sensors create shallower depth-of-field, and that’s simply not the truth.

Take a look at this example.

Okay, here is the real truth: these images are identical… same focal length, same aperture, same shutter speed, same ISO, same lighting, same distance from camera to subject. Literally the only difference is the sensor size. Look all your want, and then try to guess which one is 36x24mm sensor, and which is made with a 24x16mm sensor.

But how can these images be identical? Doesn’t everyone, everywhere know that larger sensors create shallower depth of field? Shouldn’t I “upgrade” to a bigger sensor to get shallower depth of field?

No. What’s really happening is that when you switch from a smaller sensor to a larger one, in order to create the same composition, you either have to move closer, which creates shallower depth of field, or you have to use a longer focal length, which creates shallower depth of field.

The real reason this is shrouded in myth and misconception is simple: use of the word “equivalent.” You hear and read photographers say it all the time. “I’m using a 50mm on my full-frame camera, which is equivalent to a 75mm on my APS-C camera.” They are instantly comparing apples to oranges. Every website about camera does this, and it’s fraudulent.

I know I’m not going to change the world’s mind about this, since it is so ingrained in the psyche of photography, but maybe at least a few curious, budding photographers out there will figure it out.

And don’t just take my word for it: set up a test and see for yourself. Put a lens on your full-frame and make a picture, then, without changing anything else, put that lens on a smaller-sensor camera. But don’t cheat. Don’t move, don’t change aperture, shutter speed, ISO, anything.

I made the example above in 2022, but when re-authoring this opinion in 2025, I decided to do it again. Here is the result: can you tell which one is which?

Is there any difference at all between sensor sizes? Of course there is, but it’s just not depth of field.

Here’s what’s really going on: this is the APS-C image (a 24x16mm sensor) overlaid on an FX image (36x24mm sensor.) Angle of view changes, but depth of field does not.