Does sensor size matter? Part 2 – What the heck is equivalency?

Aug 7, 2020

John Aldred

John Aldred is a photographer with over 20 years of experience in the portrait and commercial worlds. He is based in Scotland and has been an early adopter – and occasional beta tester – of almost every digital imaging technology in that time. As well as his creative visual work, John uses 3D printing, electronics and programming to create his own photography and filmmaking tools and consults for a number of brands across the industry.

Does sensor size matter? Part 2 – What the heck is equivalency?

Aug 7, 2020

John Aldred

John Aldred is a photographer with over 20 years of experience in the portrait and commercial worlds. He is based in Scotland and has been an early adopter – and occasional beta tester – of almost every digital imaging technology in that time. As well as his creative visual work, John uses 3D printing, electronics and programming to create his own photography and filmmaking tools and consults for a number of brands across the industry.

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Equivalency is one of those topics that not only confuses a lot of people but also turns into some pretty heated arguments. It’s why people think that a lens of one focal length “turns” into another when you put it on a camera with a differently sized sensor. It’s why your depth of field both does and doesn’t change at the same time.

The video above was made as a follow-up to a video recently published by The Slanted Lens to ask does size really matter?. Naturally, when comparing medium format, full-frame, APS-C and Micro Four Thirds cameras, each with their own unique sensor sizes, it raises a lot of questions. And it did. So, this video is designed to answer them.

Equivalency in this context is essentially what you’d need to do in order to get the same (or at least, largely comparable) shots on cameras with different sized sensors. When you change that one thing, you have to change other things, which causes other things to need to change as well.

In short, when the sensor size changes, you need to change your lens in order to get the same field of view. That, in turn, means you need to shoot at a different aperture in order to get the same depth of field relative to that field of view (relativity is important). This means you might need to change your shutter speed to bring the exposure under control. Or, change your ISO if the shutter speed is a vital factor for capturing motion blur.

But that’s about as far as I’m going to try to break things down with equivalency in this post because it’s all laid out in the video, and trying to write it would just make it sound even more complex – especially when I would have to preemptively counter every troll argument in the comments.

I shoot full-frame, 1.5x crop APS-C and Micro Four Thirds (which drops to a 2.2x crop when shooting 4K). I also shoot 35mm and medium format film in various aspect ratios. Equivalency is something that I’ve had to keep in my mind for a long time when picking one camera over another to shoot photos or video. And once you understand it, it’s pretty easy to work out in your head – even if it’s difficult to explain to somebody else.

But if you’re confused about crop factors, how they affect the field of view and depth of field, and how you can get pretty much the same exact shot on multiple cameras with different sensor sizes, have a watch. Maybe you’ll realise that for a lot of what most people shoot, sensor size should be the least of real and practical concerns.

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John Aldred

John Aldred

John Aldred is a photographer with over 20 years of experience in the portrait and commercial worlds. He is based in Scotland and has been an early adopter – and occasional beta tester – of almost every digital imaging technology in that time. As well as his creative visual work, John uses 3D printing, electronics and programming to create his own photography and filmmaking tools and consults for a number of brands across the industry.

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5 responses to “Does sensor size matter? Part 2 – What the heck is equivalency?”

  1. Lorenzo Morgoni Avatar
    Lorenzo Morgoni

    yep but afaik we must also take into account the specific circle of confusion for every sensor, which takes part in the DoF calculation formula
    good video btw, just a little bit confusing

  2. Adrian J Nyaoi Avatar
    Adrian J Nyaoi

    It does matter, the smaller the better, that is why iPhone is the best.

    1. John G Schickler Avatar
      John G Schickler

      Adrian J Nyaoi Please walk home, you are too drunk to drive.

    2. Adrian J Nyaoi Avatar
      Adrian J Nyaoi

      John G Schickler DUI? I drink and drive, my life, and if anyone think it is dangerous, they have a choice to stay home while I am on the road. Ha ha, freedom of movement and choice, like some people don’t want to wear mask.

  3. Richard Bierman Avatar
    Richard Bierman

    You’ve got it wrong! The bigger the sensor the better!