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

Started 7 months ago | Discussions thread
joejack951
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Re: Potential dead horse: how bad is FF's deep DoF disadvantage?
In reply to sportyaccordy, 7 months ago

sportyaccordy wrote:

DoF is entirely a product of the aperture diameter. So a 24mm F4 will have the same DoF as 48mm F8, 12mm F2 etc etc.

DoF has many factors depending on what you are trying to compare. If comparing multiple sensor sizes while holding field of view and distance to subject constant (taking the same picture), then yes, it is a product of the aperture diameter.

If comparing different focal lengths and f-stops on the same sensor size, aperture diameter is no longer the only factor because you are now comparing different pictures. Holding subject framing constant, DoF varies only with changing the f-stop (to get equivalent framing with different focal lengths distance to subject must vary though). Holding distance to subject constant, DoF varies with focal length, but the resulting photos will have nothing in common.

As someone explained to me in another thread, for equivalent photos this phenomenon cancels out larger formats' high ISO advantage for completely equivalent pictures. For example to maintain shutter speeds, that 24mm F4 on an FF camera will need to be shot at 2 ISO stops higher than 12mm F2 on an MFT camera. At which point the noise on the FF is at best the same but in some cases worse if we are talking very high ISOs.

If one is always aiming for equivalent pictures to a smaller format, then it would make no sense to shoot with a larger format.

So my question is, for folks who have used an array of different formats extensively, how much does this affect real world shooting? Did you ever find yourself frustrated with the inability to get deep DoF from larger formats, or is it not that big of a deal?

Depending on the subject, the large DoF of smaller formats can be a big advantage in macro shooting. I sell some small products and when discussing issues with the manufacturer, I find it much easier to take a close up shot with my P7700 than my D3S and 105VR because the latter yields very minimal DoF, effectively ruining the shot. For everything else, I'll take the D3S, please.

It seems to me more and more like no format is superior to another... they all have advantages and disadvantages that make them better for different kinds of photography, with no clear all around winner

It is very true that all formats have some advantage, but then some are more compromised than others. Deep DoF can be achieved on a larger format by focus stacking (not possible with moving subjects where the smaller formats are the way to go or when you just want a quick snapshot like my example above). Small formats, certainly anything smaller than m4/3s, struggle to get anywhere near the shallow DoF on a larger format.

My "slow" f/4 zoom would require an f/1.5 lens on a 1" sensor for equivalent DoF. You'll only see an f-stop that fast on a prime while my f/4 zoom can go from 24-120mm. My zoom only stops down to f/22 though whereas that f/1.5 1" theoretical prime would likely stop down to an equivalent of f/43 (2.7 x f/16). I don't think I've gone past f/16 though, and that was only when I was testing my new studio light.

Again, if your main concern is achieving equivalent shots to a smaller format, you might as well own the smaller format then.

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