Potential dead horse: how bad is FF's deep DoF disadvantage?

Started 6 months ago | Discussions thread
Lee Jay
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In reply to Mike Davis, 6 months ago

Mike Davis wrote:

Lee Jay wrote:

Lee Jay wrote:

Mike Davis wrote:

Lee Jay wrote:

sportyaccordy wrote:

So my question is, for folks who have used an array of different formats extensively, how much does this affect real world shooting?

Not at all. As you pointed out, for constant (deep) depth of field, all formats are the same.

True, except that smaller formats operate at faster shutter speeds to yield the same DoF and diffraction at any given enlargement factor and desired print resolution,

Nope - exactly the same. Just up ISO. Noise will stay the same.

Diffraction-limited DOF is also exactly the same for all formats.

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Lee Jay

If a tiny sensor yields the same DoF and diffraction at f/3.2 in a like-sized print produced by a larger sensor at f/17.7, the smaller sensor will be operating at a faster shutter speed than the larger sensor - assuming we make no changes to the lighting or ISO settings.

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But you can make changes to ISO a end up with the same noise. That's the whole point.
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Lee Jay

There's a five-stop difference between f/3.2 and f/17.7.

If the large sensor is using f/17.7 at ISO 100 to yield a given DoF, diffraction, and signal-to-noise ratio for a given print size, what ISO setting would you recommend the small sensor use if f/3.2 yields the exact same DoF, diffraction and signal-to-noise ratio in a like-sized print?

You would have to reduce the ISO at the small sensor by five stops - from ISO 100 to ISO 17.7 (coincidentally) - still shooting at f/3.2, to match the shutter speed had with ISO 100 at f/17.7 on the large sensor.

Unless you can find a tiny-sensor camera that offers ISO settings as low as 17.7, what you're suggesting assumes that users of large-sensor cameras always shoot at high ISO settings. Not true.

At low-ISO, or in other non-light-limited situations, the larger sensors have the advantage, not the smaller ones as your original statement made it sound:

"...smaller formats operate at faster shutter speeds to yield the same DoF and diffraction at any given enlargement factor and desired print resolution."

Regardless, I have shot below ISO 1 with 1/4" sensors, using stacking.

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Lee Jay

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