Why Depth of Field is NOT Effected by Sensor Size – A Demonstration

This is probably one of the most argued about topics in digital photography. For as long as we can remember people have been arguing that if you will use a camera with a larger sensor (with the same lens and same settings) you will get more depth of field (DOF) or basically better separation between your subject and its background.

Well, in this video from 2012, photographer Matt Granger (aka ThatNikonGuy) set out to disprove this claim once and for all. He used the Canon 1D-X with a Full Frame sensor and the tiny EOS-M (with its APS-C sensor) along with the same 70-200mm F/2.8 lens in exactly the same settings to shoot an object with a clear second object in the background.

Sensor Sizes in different cameras (the relative size of the sensors in the table is done to scale)

Sensors size-01-01

The resulting DOF was a clearly identical (although the EOS-M image was of course cropped due to the smaller sensor). Interestingly from the reaction to the video – lots of people continue to claim that DOF is in one way or another dependent on the sensor size…

At the end of the day, besides not having your image cropped, larger sensors will give you one clear advantage – and that is having more surface to collect light, and thus better sensitivity (when all other things being equal of course). With today’s technology you can typically expect about 1 stop more light when moving from APS-C size sensor (of a specific manufacturer) to a Full Frame camera of the same manufacturer.

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11 comments

  1. This video is completely misleading.
    Of course a larger sensor gives you smaller DOF, because you will use longer focal length to get the SAME framing you want. Its not complicated and there is no reason for so many arguments over this basic subject.
    In this video he used 2 different sensors, but he didn’t toke the SAME picture (same framing), so this is a meaningless demonstration. Obviously the sensor by itself doesn’t affect the DOF, dah…

    1. oh yeah, many websites failed to demonstrate the SAME FRAMING. they only place the smaller sensor camera at same position.

  2. As long as you use the same lens you get the same DOF. Lets say that
    you have a 85mm f/1.8 and a D7100 and than you move to a D800 and shoot
    the same image and crop it to get the same frame – you will get exactly
    the same DOF – no change. If you change the lens or the distance to the
    subject or anything else, obviously you will get a different DOF but
    this destroys the “experiment” that you are doing.

    People need to understand that the sensor has nothing to do with DOF and
    having FF on its own doesn’t give you better DOF than APS-C.

    1. But in practice whats the point of this? The idea of having a FF vs an APS-C is more options, the option of having more of the surroundings into the frame or getting closer to your subject to change the DoF, for example. You guys are arguing for the sake of arguing, pure “semantics”.

  3. I’m sorry but you are just wrong. FF does give you smaller DOF over APS-C, by 1 stop, because of the change in focal length, or focus distance, or both. If you are cropping the image, than you are not using FF… its the same as taking the picture with APS-C camera. And if you are not cropping the image, than its not the same photo (the FF photo is much wider), and the comparison is meaningless.
    Bottom line. larger sensor will produce smaller DOF, one way or another, and this is what photographers should understand.

  4. Sorry, but that is not true. The only thing you get with a larger sensor is more light (better sensitivity lower noise) not more DOF.
    The question is simple – do you get better DOF with a larger sensor? if this was a scientific experiment – the only thing that you would be allow to change in the setup is the sensor – nothing else- not the lens, not the settings and not the distance to the subject.
    When you do this – you end up with two images with the same DOF – they are not the same image because the smaller sensor dictates a narrower viewing angle. If you want to get the same frame – crop the image.
    Cropping does nothing to the DOF – think about it like this – project an image on a wall – now mark a smaller rectangle which makes it 1.5 times smaller- did you change the image in any way apart from cropping it – hell no – the same goes for smaller sensors.

  5. I already wrote in my first comment: “Obviously the sensor by itself doesn’t affect the DOF, dah…”

    My point is that this video is very misleading to photographers, because it doesn’t mention at all that larger sensor does produce smaller DOF, because of the change in the parameters of the lens (focal length and focus distance).

  6. Its not Dah – most people don’t get this. They think that the larger the sensor the more DOF you have – and this is simply not true.

    There are of course other things in play here – since this topic got a LOT of attention and tons of arguments from many people (here, on MegaPixel and elsewhere) we are going to create our own video in a few weeks talking a bit more broadly about depth of field and what actually effects it.

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