R.G. Loc: Scotland

You make the (valid) point that DOF depends on how far away the focus point is. However, the point I was making is that if you compare like with like, the small sensor camera will give a wider DOF.

The example that you posted is interesting. 1.65 - 16.38 meters sounds like quite a lot of DOF for settings of f/2, a focal length of ~28mm equiv. and a focus point 10 ft away. Out of curiosity, how would the DOF compare if a FF camera was used to capture a similar image?

srt101fan

Yikes, Linda, are you turning into a "gearhead"? 😁

Linda From Maine Loc: Yakima, Washington

Ha! I admit to a certain curiosity about my own cameras and lenses, but my reason for creating the topic was to confirm that when I mentioned the word diffraction with reference to someone using f/29 that I was not totally wrong. Not that there's anything wrong with being totally wrong on UHH. Ooops - snark alert, snark alert!

selmslie Loc: Fernandina Beach, FL, USA

It's significantly different.

You should play with the calculator.

(Download)

R.G. Loc: Scotland

That would appear to be conclusive proof that sensor size does have a significant effect on DOF (all other things being equal).

R.G. Loc: Scotland

It looks like we've lost her to the dark side lol.

Linda From Maine Loc: Yakima, Washington

🤗🤗

Peter Boyd Loc: Blyth nr. Newcastle U.K.

As far as I'm aware, diffraction occurs with every lens, as 'Scottie' was fond of saying in 'Star Trek' - "Ye canna change the laws o' physics Cap'n".

R.G. Loc: Scotland

Just out of curiosity, this is what an m4/3 camera gives. The difference is not so vivid but still significant.

(EDIT - wrong image posted first time round).
.

(Download)

pesfls Loc: Oregon, USA

True. I readily notice the difference in dof between my ff and m4/3 bodies. Different animals. But I’m more interested in the practical effects rather than the very technical aspects. But that’s just me.

srt101fan

😁

R.G. Loc: Scotland

A good point, but many folks are unclear as to what the practical effects are, especially when they're being told that sensor size doesn't affect DOF.

selmslie Loc: Fernandina Beach, FL, USA

The actual focal length (rather than the 35mm full frame equivalent) makes a big difference.

The other point that Cambridge in Colour should have emphasized is that, if you take an image and then crop it, it will also make a big difference.

For example, if you use a 50mm lens on a full frame camera and then crop it by a factor of 1.5x, the resulting DOF will be the same as if you had used a 1.5x crop sensor in the first place with the 50mm lens. But a 50mm lens on a 1.5x crop factor sensor gives you the same field of view as a 75mm lens on a full frame camera.

It can all get to be more trouble than it's worth. It's the sort of information that we can study until we understand it and then go our merry way without dwelling on it.

The only thing that really matters is to understand what it takes to get a shallow DOF when we want it. A full frame sensor makes that easier. Medium and large format almost guarantees it unless you use very small apertures close to the diffraction limit.

A smaller sensor makes a deep DOF almost inevitable, even when wide open.

amfoto1 Loc: San Jose, Calif. USA

Diffraction is an optical effect. It's immutable. It cannot be avoided unless and until someone comes up with a lens that doesn't use any optical elements or an aperture to control light. Since both these things are impossible, there's nothing that can be done about diffraction other than to avoid using "too small" apertures.

Diffraction causes the loss of fine detail, which can make an image look "soft" and objects appear "plasticky". You can counteract it to some degree in post-processing with sharpening, but there's no recovering the fine detail that was lost. It's gone and there's no getting it back.

The best solution is to use "not too small"r aperture and deal with any lack of depth of field using other means, such as focus stacking an image. That technique is pretty much limited to stationary objects, so it generally won't work with live subjects or anything else that moves such as ocean waves or wind blown foliage.

Sensor size is an indirect factor effecting the appearance of diffraction. The smaller the sensor, the more diffraction will be a problem in any given size of print (or any other use of an image). This is simply because to finish an image from a smaller sensor requires greater magnification.

And, the higher resolution the camera's sensor, the more diffraction will occur. Or, one might say, the more obvious it will be. Basically, more detail is being captured by the sensor, so there is more to lose to the optical effect. (To some extent, the same might be true of higher resolution lenses. I really don't know.) But, also and importantly, the higher image resolution, the larger and more critically you will be viewing it on a computer screen if you view all images "at 100%". A 12MP image "at 100%" is half as large as a 24MP image at the same magnification... or you might say you are viewing the higher resolution image "more critically".

Print size (or other usage of the image) is a factor, as would be any cropping. There's going to be a difference viewing a billboard from 100 feet versus viewing an 8x10" print from one foot.

For comparison's sake, the following Diffraction Limited Aperture (DLA) is based upon viewing images at 100% on a typical computer monitor (native resolution around 100 ppi). Take into consideration that this IS NOT how most people will ever view the image. In most cases it's a great deal more magnified.Also, the "DLA" is the aperture at which diffraction first begins to occur visibly at that magnification. The effect will increase incrementally as you stop down to smaller apertures. It's usually quite apparent one or two stops smaller than the DLA.

CX or 1" sensor with 15MP... f/4.4
M4/3 camera with 15MP... f/6
APS-C camera with 15MP... f/6.9
Full frame with 15MP... f/11.4

CX or 1" sensor with 20MP... f/3.8
M4/3 camera with 20MP... f/5.2
APS-C camera with 20MP... f/5.9
Full frame camera w/ 20MP... f/9.9

APS-C sensor with 24MP... f/5.4
Full frame sensor w/24MP... f/9

APS-C sensor with 30MP... f/4.9
Full frame sensor, 30MP... f/8.1
Medium format, 30MP... f/14

Full frame sensor, 50MP... f/6.2
Medium format, 50MP... f/10.8

Full frame, 70MP... f/5.3
Medium format, 70MP... f/9.1

The above are approximations of current formats and resolutions. For example, there are full frame cameras with 46MP and 61MP sensors. None currently has 70MP, but there are strong rumors of models in the near future that will have higher resolution than that. Medium format digital are available in 100MP and higher resolution, too.

There is considerably more detail about diffraction here:

https://www.cambridgeincolour.com/tutorials/diffraction-photography.htm

sippyjug104 Loc: Missouri

Diffraction is a result of the Laws of Physics and the Laws of Physics are not just a good idea or recommendation...'It's the LAW'.