Canon Full Frame Mirrorless Talk [CR1]

[Hflm]

Reach is a function of pixel pitch not sensor size. If the pixel density of 5DSR is (give or take) pretty similar to EM-1.2 they both have the same 'reach' with a 300mm lens.
FOV is irrelevant if you are focal length limited.

Exactly!

Look at the 1DX2, the 5DSR, and the 7D2....

Slap a 400F5.6 on each body, stand in the same spot and take a picture of the same object at F5.6....

Let's call the 1DX2 shot the "standard image" to compare against.....

The 5DSR image will have an identical field of view as the 1DX2 image and the DOF will be identical, but the image will be sampled more densely.

The 7D2 image will have only 62% of the field of view of the 1DX2 image, the DOF will be identical, and the image will be sampled more densely.

The fun part is the comparison between the 5DSR and the 7D2..... both cameras have the same pixel pitch and are approximately at the same level of sensor technology... If you crop the 5DSR image to the same field of view as the 7D2 image, the two images should be identical. Same DOF, same sampling density......

Lenses do not magically change properties when swapped onto different bodies. The optics do not change. The photon entering the lens does not know what sensor is at the far end of the lens and can not change it's path based on that.....

DOF does not change because you have moved between crop and FF. DOF changes when you walk closer (or further) from your subject (framing) or when you change the aperture of the lens.

DOF is nothing physical in itself. It depends on viewing size, too (i.e. size of COC), besides distance and focal length. Look here, equation 9 and 12: http://toothwalker.org/optics/dofderivation.html .
As the COC is differently taken for both formats, DOF decreases for APSC in case of same focal length, aperture and distance, as we want the same relation between diagonal and COC, which is confirmed by a dof calculator, as long as you print to the same sized image!
Zeiss: "The size of the object field is reduced by the crop factor while the object-side light cones remain the same, as long as we use the same lens and do not change the aperture setting. That is why the points of the light cones may not be located so far from the focal plane if we want to maintain the same ratio of diagonal to circle of confusion. Reducing the size of the film format therefore reduces the depth of field by the crop factor."
Use http://dofmaster.com/dofjs.html to check it: e.g. 85mm/f2 at 5m distance. DOF = 27.2 cm (APSC) and 40.9cm (D800).

Only when viewing the APSC image at a smaller size related to the crop factor, your DOF will be the same. The important thing is the size of the COC relative to the size of the sensor, to get the impression that a point on the object side is projected within the COC to be still seen as a point in the image plane.

If you crop the FF image to APSC, you change the magnification which goes into the DOF equation as 1/M^2, influencing the perceived DOF (for same output size). The larger you display the image, the more obvious it will become that deviations from the "plane of perfect focus" are out of focus, and the smaller you display the image, the less obvious it will be. So what is appearing to the human eye to be in focus is dependent on viewing size (and therefore cropping and magnification) and distance to the print/image, which is used to define COC, which then determines the DOF.

 

[neuroanatomist]

Because a full frame sensor is 4 times bigger than the M 4/3 Olympus, you’ll have the equivalent of a 600mm f/8 lens.

Compared to which FF camera? Not the 5DSR

@Mikehit, he's talking about equivalence, which is the proper way to compare sensor formats. Sensor area impacts lots of important factors, including image noise and magnification (which, along with aperture, determines depth of field). Moreover, he's correctly stated the equivalence – a 300/4 on m4/3 is equivalent to a 600/8 on FF. Many people in this forum and elsewhere fail to grasp the concept, notably including Panasonic...well, I'm sure they do get it, but for marketing reasons they chose to lie and print 25-600mm f/2.8 on the barrel of the FZ200. Somehow, I don't think Panasonic made a superzoom P&S with a 214mm/8.4" front element.

And f2.8 DOF does not become f8 DOF - you don't magically de-blur that background just because you are magnifying the image.

You're right, it's not magic…it's physics. DoF is a function of aperture and magnification, and if you increase magnification, you increase DoF. A DoF calculation assumes a fixed output size and viewing distance. For subjects framed identically, the image projected on to a m4/3 sensor will be half the physical size of the same image projected onto a FF sensor, so to achieve the same output size the image from the smaller sensor must be magnified twice as much. Conceptually though, it's easier to phrase that using the other side of the equation…aperture. Thus, we say that f/4 on m4/3 gives equivalent DoF to f/8 on FF.

 

[neuroanatomist]

Lenses do not magically change properties when swapped onto different bodies. The optics do not change. The photon entering the lens does not know what sensor is at the far end of the lens and can not change it's path based on that.....

DOF does not change because you have moved between crop and FF. DOF changes when you walk closer (or further) from your subject (framing) or when you change the aperture of the lens.

Sorry, but you're out of your depth (of field) on this one, Don. I think you are trapped within the circle of confusion…

Speaking of which, if you actually change nothing else, i.e. keep subject distance and aperture the same, use the same lens and focal length, and only swap out the camera…the depth of field will actually be shallower with the smaller sensor. So yes, either way sensor size absolutely affects DoF, whether you change magnification by changing the subject distance, or whether you merely change the sensor behind the lens.

 

[Mikehit]

Lenses do not magically change properties when swapped onto different bodies. The optics do not change. The photon entering the lens does not know what sensor is at the far end of the lens and can not change it's path based on that.....

DOF does not change because you have moved between crop and FF. DOF changes when you walk closer (or further) from your subject (framing) or when you change the aperture of the lens.

Sorry, but you're out of your depth (of field) on this one, Don. I think you are trapped within the circle of confusion…

Speaking of which, if you actually change nothing else, i.e. keep subject distance and aperture the same, use the same lens and focal length, and only swap out the camera…the depth of field will actually be shallower with the smaller sensor. So yes, either way sensor size absolutely affects DoF, whether you change magnification by changing the subject distance, or whether you merely change the sensor behind the lens.

This is why I asked

But... are you talking same framing or focal length limited? The former has some merit, the latter definitely not

.

A 300mm lens will project the same image size onto the sensor irrespective of sensor size. If you need to crop and MFT image you will need to crop a FF image as well. And if you crop to the same FOV, the DOF for both formats will be dependent on pixel density (not sensor size).

If you are talking about a frame-filling image then that is a different thing.

 

[Mikehit]

I told you what I what talking about, light gathering, a FF sensor gathers 3.81 times as much light.

The difficulty with linear resolution is there is a difference in aspect ratio (4:3 compared to 3:2) so it’s apples to oranges. Let’s just compare megapixels: 20.1 versus 13.2 (50.3/3.81) so the E-M1 Mark II has 65% more megapixels and that’s not even close to equal. It’s about the same difference as between the original 5D and the 5D Mark II.

That is what confused me.
You said you are not talking about resolution - but pixels give resolution. More pixels = more resolution = effect on DOF.
I am not sure what effect 'light gathering' has on it. Or were you not talking about DOF at that point (most people refer to 'equivalence regards DOF but maybe you were not in this case?

 

[Orangutan]

Lenses do not magically change properties when swapped onto different bodies. The optics do not change. The photon entering the lens does not know what sensor is at the far end of the lens and can not change it's path based on that.....

DOF does not change because you have moved between crop and FF. DOF changes when you walk closer (or further) from your subject (framing) or when you change the aperture of the lens.

Sorry, but you're out of your depth (of field) on this one, Don. I think you are trapped within the circle of confusion…

Speaking of which, if you actually change nothing else, i.e. keep subject distance and aperture the same, use the same lens and focal length, and only swap out the camera…the depth of field will actually be shallower with the smaller sensor. So yes, either way sensor size absolutely affects DoF, whether you change magnification by changing the subject distance, or whether you merely change the sensor behind the lens.

Are you talking about equal framing or equal distance? This discussion is meaningless unless we're talking equal distance, in which case I believe Don is correct. This can be seen trivially in that a FF sensor can be viewed as containing within in it smaller sensors of any size, and the DoF is the same (aside from lens distortions) across the sensor. If you want to discuss equal framing then please be explicit about that.

 

[neuroanatomist]

Lenses do not magically change properties when swapped onto different bodies. The optics do not change. The photon entering the lens does not know what sensor is at the far end of the lens and can not change it's path based on that.....

DOF does not change because you have moved between crop and FF. DOF changes when you walk closer (or further) from your subject (framing) or when you change the aperture of the lens.

Sorry, but you're out of your depth (of field) on this one, Don. I think you are trapped within the circle of confusion…

Speaking of which, if you actually change nothing else, i.e. keep subject distance and aperture the same, use the same lens and focal length, and only swap out the camera…the depth of field will actually be shallower with the smaller sensor. So yes, either way sensor size absolutely affects DoF, whether you change magnification by changing the subject distance, or whether you merely change the sensor behind the lens.

Are you talking about equal framing or equal distance? This discussion is meaningless unless we're talking equal distance, in which case I believe Don is correct. This can be seen trivially in that a FF sensor can be viewed as containing within in it smaller sensors of any size, and the DoF is the same (aside from lens distortions) across the sensor. If you want to discuss equal framing then please be explicit about that.

Sorry if that was unclear. When I said "Change nothing else but the camera," I meant change nothing else. If all you change is the sensor size, then obviously you are changing the framing. In that case, depth of field is shallower with the smaller sensor because the circle of confusion is smaller. If you change the subject distance to match the framing, i.e., moved further away with the smaller sensor, then depth of field is deeper with the smaller sensor. But either way, depth of field is changing with sensor size.

Don's point was that sensor size does not affect depth of field, only lens and subject distance parameters do so. He's wrong.

 

[BurningPlatform]

The crop-DoF debate finally reaches CanonRumors. The discussion here (and Don, specifically), is about visible DoF when you have the same framing with different crop factors. That is also what you use when you say that a mFT 100mm is FF 200mm equivalent.

If you photograph a subject from the same distance with an mFT camera with aperture 4 and 100mm lens (200mm FF equivalent), you get (approximately) the same number of circles of confusion across the frame on the out-of-focus background objects as you get from a real 200mm lens with aperture 8 on an FF camera.

So the question is, why does e.g. Panasonic quote the FF equivalence when talking about the focal length but not when talking about the aperture?

 

[Mikehit]

So the question is, why does e.g. Panasonic quote the FF equivalence when talking about the focal length but not when talking about the aperture?

My guess is because DOF is not just sensor size but pixel density as well. And at the end of the day, people care more for 'reach' than they do about DOF.

 

[bdunbar79]

So the question is, why does e.g. Panasonic quote the FF equivalence when talking about the focal length but not when talking about the aperture?

My guess is because DOF is not just sensor size but pixel density as well. And at the end of the day, people care more for 'reach' than they do about DOF.

Well yes, it is affected by subject distance, focal length, aperture, and magnification. That's where the sensor size matters.

 

[romanr74]

Lenses do not magically change properties when swapped onto different bodies. The optics do not change. The photon entering the lens does not know what sensor is at the far end of the lens and can not change it's path based on that.....

DOF does not change because you have moved between crop and FF. DOF changes when you walk closer (or further) from your subject (framing) or when you change the aperture of the lens.

Sorry, but you're out of your depth (of field) on this one, Don. I think you are trapped within the circle of confusion…

Speaking of which, if you actually change nothing else, i.e. keep subject distance and aperture the same, use the same lens and focal length, and only swap out the camera…the depth of field will actually be shallower with the smaller sensor. So yes, either way sensor size absolutely affects DoF, whether you change magnification by changing the subject distance, or whether you merely change the sensor behind the lens.

Are you talking about equal framing or equal distance? This discussion is meaningless unless we're talking equal distance, in which case I believe Don is correct. This can be seen trivially in that a FF sensor can be viewed as containing within in it smaller sensors of any size, and the DoF is the same (aside from lens distortions) across the sensor. If you want to discuss equal framing then please be explicit about that.

Sorry if that was unclear. When I said "Change nothing else but the camera," I meant change nothing else. If all you change is the sensor size, then obviously you are changing the framing. In that case, depth of field is shallower with the smaller sensor because the circle of confusion is smaller. If you change the subject distance to match the framing, i.e., moved further away with the smaller sensor, then depth of field is deeper with the smaller sensor. But either way, depth of field is changing with sensor size.

Don's point was that sensor size does not affect depth of field, only lens and subject distance parameters do so. He's wrong.

Why is the circle of confusion changing? Isn't the only thing changing the size of the COC relative to the sensor size (but not the absolute size of the COC)?

 

[Orangutan]

If all you change is the sensor size, then obviously you are changing the framing. In that case, depth of field is shallower with the smaller sensor because the circle of confusion is smaller.

Please explain this: I can convert a FF to a smaller sensor by putting tape over the outer edges. Are you saying that this would affect the circle of confusion, and therefore the DoF? If so, I've got some reading to do.

 

[midluk]

Of course the usual equivalence breaks down when you begin to not look at complete pictures but crops thereof (e.g. on a monitor zoomed in at 100%). You of course have to do the calculations for the new modified crop factors.

And the usual equivalence assumes your resolution is high enough to be invisible at the usual size of the prints and viewing distance.

 

[BurningPlatform]

So the question is, why does e.g. Panasonic quote the FF equivalence when talking about the focal length but not when talking about the aperture?

My guess is because DOF is not just sensor size but pixel density as well. And at the end of the day, people care more for 'reach' than they do about DOF.

But many people think they get equivalent bokeh from a severely cropped 2.8 lens than they do from an FF equivalent 2.8 lens. As bokeh is really the reverse of DoF, that is really not the case. Bokeh is not related to pixel pitch, but is related to the whole frame.

Also, giving the equivalent aperture would also make it more clear how much less light the sensor in total has to work with with a cropped sensor. E.g. a 20 megapixel FF sensor gets 4 times more light per pixel than an mFT 20 megapixel sensor, and this does mean that either the sensor has to be much more efficient, or you get more noise and less high ISO performance. As there is not too much room to increase the Quantum Efficiency of sensors any more, this problem with crop will not disappear.

 

[bdunbar79]

As an example, suppose I am using a 7D with a 100mm lens set at f/4, and my subject is 25 meters away. My DOF is 9.81 meters. If I don't do anything else at all, and simply swap out to a 1Dx, my DOF changes to 16.4 meters. All I changed was the sensor. And this has to do with magnification. DOF calculators of course assume the same output size and same viewing distance.

 

[neuroanatomist]

So the question is, why does e.g. Panasonic quote the FF equivalence when talking about the focal length but not when talking about the aperture?

My guess is because DOF is not just sensor size but pixel density as well. And at the end of the day, people care more for 'reach' than they do about DOF.

I think the obvious answer is marketing. 25-600mm f/2.8 sounds good. 25-600mm f/16...not so much (it's a 5.6x crop sensor). But if you want to rationalize it, while sensor size affects DoF, it doesn't affect 'exposure'. In other words, for a given scene such that 1/100 s, f/2.8, ISO 400 gives the desired exposure, those same camera settings will give the same exposure (in terms of image brightness) whether you're using a FF sensor, m4/3, or Panasonic's FZ200. But that's a red herring, because in addition to DoF, the level of image noise is determined by the total light gathered, which is proportional to the sensor size. So, an image taken with those settings on the Panasonic 5.6x crop sensor would have the same brightness as an equivalent image taken on a FF sensor, but the DoF would be equivalent to f/16 on FF, and the image noise would be equivalent to ISO 16,000 on FF.

 

[bdunbar79]

If all you change is the sensor size, then obviously you are changing the framing. In that case, depth of field is shallower with the smaller sensor because the circle of confusion is smaller.

Please explain this: I can convert a FF to a smaller sensor by putting tape over the outer edges. Are you saying that this would affect the circle of confusion, and therefore the DoF? If so, I've got some reading to do.

When these discussions about sensor size and DOF take place, seems some get lost whirrrrrrring round and round in the circle of confusion.

 

[Sporgon]

So the question is, why does e.g. Panasonic quote the FF equivalence when talking about the focal length but not when talking about the aperture?

Because of exposure. From an exposure point of view an f/2.8 lens is an f/2.8 lens irrespective of what sized sensor it is put in front of, it just produces a different optical effect depending on sensor size. Just because a FF f/2.8 lens produces a DOF on crop closer to an f/4 lens on FF doesn't make that an f/4 lens in any way, shape or form. To put a different f stop on a lens from the one it really is could lead to exposure confusion.

Of course you can say the same thing about focal length, a 50mm lens is a 50mm lens ! However in this case it is harmless enough to give it's FF equivalent focal length, or FOV, as it is not effecting anything else, and can be a benefit in understanding what FOV the lens will be equal to on a given sensor size.

 

[bdunbar79]

Lenses do not magically change properties when swapped onto different bodies. The optics do not change. The photon entering the lens does not know what sensor is at the far end of the lens and can not change it's path based on that.....

DOF does not change because you have moved between crop and FF. DOF changes when you walk closer (or further) from your subject (framing) or when you change the aperture of the lens.

Sorry, but you're out of your depth (of field) on this one, Don. I think you are trapped within the circle of confusion…

Speaking of which, if you actually change nothing else, i.e. keep subject distance and aperture the same, use the same lens and focal length, and only swap out the camera…the depth of field will actually be shallower with the smaller sensor. So yes, either way sensor size absolutely affects DoF, whether you change magnification by changing the subject distance, or whether you merely change the sensor behind the lens.

Are you talking about equal framing or equal distance? This discussion is meaningless unless we're talking equal distance, in which case I believe Don is correct. This can be seen trivially in that a FF sensor can be viewed as containing within in it smaller sensors of any size, and the DoF is the same (aside from lens distortions) across the sensor. If you want to discuss equal framing then please be explicit about that.

Sorry if that was unclear. When I said "Change nothing else but the camera," I meant change nothing else. If all you change is the sensor size, then obviously you are changing the framing. In that case, depth of field is shallower with the smaller sensor because the circle of confusion is smaller. If you change the subject distance to match the framing, i.e., moved further away with the smaller sensor, then depth of field is deeper with the smaller sensor. But either way, depth of field is changing with sensor size.

Don's point was that sensor size does not affect depth of field, only lens and subject distance parameters do so. He's wrong.

Why is the circle of confusion changing? Isn't the only thing changing the size of the COC relative to the sensor size (but not the absolute size of the COC)?

If you assume the same output size and viewing distance, the smaller sensor's "image" had to undergo a larger enlargement to get to that same size, vs. a larger sensor's image. The enlargement ratio is larger.

 

[romanr74]

Lenses do not magically change properties when swapped onto different bodies. The optics do not change. The photon entering the lens does not know what sensor is at the far end of the lens and can not change it's path based on that.....

DOF does not change because you have moved between crop and FF. DOF changes when you walk closer (or further) from your subject (framing) or when you change the aperture of the lens.

Sorry, but you're out of your depth (of field) on this one, Don. I think you are trapped within the circle of confusion…

Speaking of which, if you actually change nothing else, i.e. keep subject distance and aperture the same, use the same lens and focal length, and only swap out the camera…the depth of field will actually be shallower with the smaller sensor. So yes, either way sensor size absolutely affects DoF, whether you change magnification by changing the subject distance, or whether you merely change the sensor behind the lens.

Are you talking about equal framing or equal distance? This discussion is meaningless unless we're talking equal distance, in which case I believe Don is correct. This can be seen trivially in that a FF sensor can be viewed as containing within in it smaller sensors of any size, and the DoF is the same (aside from lens distortions) across the sensor. If you want to discuss equal framing then please be explicit about that.

Sorry if that was unclear. When I said "Change nothing else but the camera," I meant change nothing else. If all you change is the sensor size, then obviously you are changing the framing. In that case, depth of field is shallower with the smaller sensor because the circle of confusion is smaller. If you change the subject distance to match the framing, i.e., moved further away with the smaller sensor, then depth of field is deeper with the smaller sensor. But either way, depth of field is changing with sensor size.

Don's point was that sensor size does not affect depth of field, only lens and subject distance parameters do so. He's wrong.

Why is the circle of confusion changing? Isn't the only thing changing the size of the COC relative to the sensor size (but not the absolute size of the COC)?

If you assume the same output size and viewing distance, the smaller sensor's "image" had to undergo a larger enlargement to get to that same size, vs. a larger sensor's image. The enlargement ratio is larger.

But through magnifying to same picture size...