A BSI APS-C EOS R camera is coming in the second half of 2022 [CR2]

Dalantech

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Feb 12, 2015
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Not trying to sell you snake oil, but..no...it's not the same. Cropping alters the composition. It is easier to create your composition when you can use the entire sensor and viewfinder compared to anticipating where you will crop for a cropped composition. And since (as others have mentioned) there are no FF cameras with the same pixel density as the highest MP crop sensors, you will have lower pixel density.
My point was that cropping an image does not change the magnification. FWIW: I do all of my composition and framing with the view finder and only crop in post if someone wants a square print or I want the subject to be larger in the frame for a print.
 

Dalantech

Gatekeeper to the Small World
Feb 12, 2015
111
89
I agree. The advantage of a crop camera is just about pixels on subject for a given distance and lens, and apparent DOF for a particular field of view.
Great for a macro shooter like me cause I can fill the frame with the subject at lower magnifications than shooting with a full frame sensor, and that drop in mag gives me more depth of field. Could get the exact same effect shooting full frame and cropping in post to the same crop factor though, and I am getting tempted to get a Canon R5. If Canon comes out with an MP-E 65mm lens with an RF mount I will pull the trigger.
 
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neuroanatomist

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My point was that cropping an image does not change the magnification. FWIW: I do all of my composition and framing with the view finder and only crop in post if someone wants a square print or I want the subject to be larger in the frame for a print.
Cropping doesn’t change the optical magnification, but it does change final magnification. Consider your example – if you are making a 16x20 print, and you crop in post because you want the subject to be larger in the frame for that print, the subject is enlarged further with the crop.

The same applies to DoF. To compare DoF under various conditions, certain parameters are held constant, typically an assumed viewing size of an 8x10 print viewed at 25 cm. Thus, if you shoot at 1:1 optical magnification and crop the output (regardless of whether that crop is in post or with a smaller sensor), the magnification of the subject is greater and the cropped image will have shallower DoF (usually the opposite of what you want at 1:1 where DoF is already very shallow).
 
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Dalantech

Gatekeeper to the Small World
Feb 12, 2015
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Cropping doesn’t change the optical magnification, but it does change final magnification. Consider your example – if you are making a 16x20 print, and you crop in post because you want the subject to be larger in the frame for that print, the subject is enlarged further with the crop.

The same applies to DoF. To compare DoF under various conditions, certain parameters are held constant, typically an assumed viewing size of an 8x10 print viewed at 25 cm. Thus, if you shoot at 1:1 optical magnification and crop the output (regardless of whether that crop is in post or with a smaller sensor), the magnification of the subject is greater and the cropped image will have shallower DoF (usually the opposite of what you want at 1:1 where DoF is already very shallow).

"Cropping doesn’t change the optical magnification" -you should have just stopped right there, cause that is the only part of your reply that is correct. Cropping does not change the magnification of an image, and it most definitely does not change the depth of field. The only thing cropping does is make the subject look larger in the frame -it creates an enlargement. If you actually increased the mag then you would be able to resolve finer details (baring diffraction and lens characteristics). Cropping will not reveal detail that was not already in the image. Magnification and enlargement are not interchangeable terms. Although people use them incorrectly in the same context in much the same way as closeup and macro are misused.
 

neuroanatomist

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"Cropping doesn’t change the optical magnification" -you should have just stopped right there, cause that is the only part of your reply that is correct. Cropping does not change the magnification of an image, and it most definitely does not change the depth of field. The only thing cropping does is make the subject look larger in the frame -it creates an enlargement. If you actually increased the mag then you would be able to resolve finer details (baring diffraction and lens characteristics). Cropping will not reveal detail that was not already in the image. Magnification and enlargement are not interchangeable terms. Although people use them incorrectly in the same context in much the same way as closeup and macro are misused.
“Magnification and enlargement are not interchangeable terms.” You should have led with that and just stopped there, The rest of your post is incorrect. While you are correct that I inappropriately used the term magnification when enlargement was the correct word, enlargement most certainly does affect depth of field.

‘Making the subject look larger in the frame’ decreases the DoF. As stated above, the underlying assumption is that the viewing size (‘frame’) is constant. If you crop out the a 4 x 6 area of an 8 x 10 print and print it at 4 x 6, the DoF won’t change. But if you enlarge that 4 x 6 area to print at 8 x 10, the DoF will be shallower.
 
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Dalantech

Gatekeeper to the Small World
Feb 12, 2015
111
89
“Magnification and enlargement are not interchangeable terms.” You should have led with that and just stopped there, The rest of your post is incorrect. While you are correct that I inappropriately used the term magnification when enlargement was the correct word, enlargement most certainly does affect depth of field.

‘Making the subject look larger in the frame’ decreases the DoF. As stated above, the underlying assumption is that the viewing size (‘frame’) is constant. If you crop out the a 4 x 6 area of an 8 x 10 print and print it at 4 x 6, the DoF won’t change. But if you enlarge that 4 x 6 area to print at 8 x 10, the DoF will be shallower.
You and I are gonna have to agree to disagree on that last sentence. Depth of field, detail, and magnification are fixed as soon as you press the shutter release. Cropping will not reveal anything that was not already in the image.
 

Distinctly Average

EOS M6 Mark II
Sep 30, 2021
61
158
“Magnification and enlargement are not interchangeable terms.” You should have led with that and just stopped there, The rest of your post is incorrect. While you are correct that I inappropriately used the term magnification when enlargement was the correct word, enlargement most certainly does affect depth of field.

‘Making the subject look larger in the frame’ decreases the DoF. As stated above, the underlying assumption is that the viewing size (‘frame’) is constant. If you crop out the a 4 x 6 area of an 8 x 10 print and print it at 4 x 6, the DoF won’t change. But if you enlarge that 4 x 6 area to print at 8 x 10, the DoF will be shallower.
Surely with a given lens only the aperture and distance from subject change DOF?

How can enlarging a shot in post change what is captured? Please explain as I just have no idea why you think that would be the case!
 

neuroanatomist

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You and I are gonna have to agree to disagree on that last sentence. Depth of field, detail, and magnification are fixed as soon as you press the shutter release. Cropping will not reveal anything that was not already in the image.
We can disagree, but only one of us is right. I suspect you don't understand the role of the circle of confusion (CoC) in determining the DoF. You may want to read up on that a bit. It's why, for example, an image viewed at a small size appears to have deeper DoF. Here's an example where the hair and flower appear in focus at small viewing size, but in reality only the flower is in focus. The reduction in size of the full image increased the DoF because it changed the perceived sharpness of the image. The same is true in reverse – enlarging an image results in a shallower DoF.

CoC.jpg


It's ok if you don't understand the concept, even though it's called the circle of confusion for reasons that have nothing to do with people being confused about it, many people are.

DoF calculators take CoC into account for their calculations. Here's an example from one such calculator, a shot at 100mm f/4 with a subject distance of 50 cm. If you change only the sensor size, you see that the FF sensor has a deeper DoF than the APS-C sensor, because the smaller sensor has a smaller CoC, so the resulting image must be enlarged more for final viewing (again, for comparison purposes we assume a fixed output size and viewing distance).

Screen Shot 2021-10-05 at 1.44.31 PM.png
Screen Shot 2021-10-05 at 1.44.37 PM.png


If you pick an even smaller sensor, like the 1" sensor in the Nikon 1, the DoF gets even shallower, because a deeper crop means even greater enlargement is needed.

Screen Shot 2021-10-05 at 1.48.09 PM.png
 
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Distinctly Average

EOS M6 Mark II
Sep 30, 2021
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We can disagree, but only one of us is right. I suspect you don't understand the role of the circle of confusion (CoC) in determining the DoF. You may want to read up on that a bit. It's why, for example, an image viewed at a small size appears to have deeper DoF. Here's an example where the hair and flower appear in focus at small viewing size, but in reality only the flower is in focus. The reduction in size of the full image increased the DoF because it changed the perceived sharpness of the image. The same is true in reverse – enlarging an image results in a shallower DoF.

View attachment 200620
What you are showing there has nothing to do with DOF. The image is taken already so the DOF cannot change. What you are seeing is the enlargement has less data in any given region. This leads to a perception of softness when in truth nothing has changed. We can add to that artificial interpolation that makes everything seem even softer.
It's ok if you don't understand the concept, even though it's called the circle of confusion for reasons that have nothing to do with people being confused about it, many people are.

DoF calculators take CoC into account for their calculations. Here's an example from one such calculator, a shot at 100mm f/4 with a subject distance of 50 cm. If you change only the sensor size, you see that the FF sensor has a deeper DoF than the APS-C sensor, because the smaller sensor has a smaller CoC, so the resulting image must be enlarged more for final viewing (again, for comparison purposes we assume a fixed output size and viewing distance).

View attachment 200621 View attachment 200622

If you pick an even smaller sensor, like the 1" sensor in the Nikon 1, the DoF gets even shallower, because a deeper crop means even greater enlargement is needed.

View attachment 200623
Yes, they do account for circle of confusion. You need to understand why there is a difference, and that is down to ratios of the size of the subject on the sensor. It is a perceived change, not an absolute one. It is made on the assumption the resulting image will be displayed age the same size in both cases.
 

neuroanatomist

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What you are showing there has nothing to do with DOF. The image is taken already so the DOF cannot change. What you are seeing is the enlargement has less data in any given region. This leads to a perception of softness when in truth nothing has changed. We can add to that artificial interpolation that makes everything seem even softer.
Depth of field includes a component determined by perception. Visual acuity is part of what determines depth of field, so when you and I look at the same image printed at the same size, we may perceive a different depth of field if we have sufficiently different visual acuity.

It is made on the assumption the resulting image will be displayed age the same size in both cases.
Do you believe it’s valid to compare a 4x6 print with a billboard? Or a 4x6 print viewed at arms length versus from across the room? Personally, I do not.
 

Distinctly Average

EOS M6 Mark II
Sep 30, 2021
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Sorry, but if you think that only aperture and subject distance alone determine depth of field, then you don’t understand DoF completely.
No, but these are the main influences.
Depth of field includes a component determined by perception. Visual acuity is part of what determines depth of field, so when you and I look at the same image printed at the same size, we may perceive a different depth of field if we have sufficiently different visual acuity.


Do you believe it’s valid to compare a 4x6 print with a billboard? Or a 4x6 print viewed at arms length versus from across the room? Personally, I do not.
I think we are cross talking on different concepts of DOF. The traditional concept does have limitations. Camera manufacturers for instance base thei markings on this concept and use a set viewing size and distance of the resulting print, an 8*10 viewed at 1 foot IIRC.
 

neuroanatomist

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No, but these are the main influences.
Agreed, but not the only factors. For example, if you change the subject distance to match framing between FF and APS-C, that has a larger effect than the difference in CoC from different size sensors or a post-capture crop at the same subject distance (and the effect is in the opposite direction).

But CoC does matter. Some people believe an APS-C sensor is better for macro, because it gives greater DoF. But that’s only true at the same framing. I shoot with both the 100L and the MP-E 65, I generally use FF because at a given magnification it gives a deeper DoF.

I think we are cross talking on different concepts of DOF. The traditional concept does have limitations. Camera manufacturers for instance base thei markings on this concept and use a set viewing size and distance of the resulting print, an 8*10 viewed at 1 foot IIRC.
Those assumptions (8x10 print, 12” viewing distance) are the same ones typically used for DoF calculators. What other concept of DoF is there? I mean, you could compare an image from a FF sensor shown on a 38” display with an image at the same focal length, focus distance and aperture from an APS-C sensor shown on a 24” display and say the DoF is the same, but…why? If you view them both on the same monitor, the FF image will have a deeper DoF.

DoF as an abstract concept isn’t very useful. What is the relevance of the DoF in an image that you aren’t viewing? When you view an image, how you view it (enlargement, viewing size and distance) affects the DoF. Werner Karl Heisenberg’s principle applied (loosely) to photography.
 

unfocused

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Jul 20, 2010
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Oh boy! We've been through this so many times. I'd like to know what, other than lens aperture, distance to subject and focal length of the lens, is going to affect depth of field? Real depth of field, not perception of depth of field.

In this example the depth of field does not change.

Here's an example where the hair and flower appear in focus at small viewing size, but in reality only the flower is in focus. The reduction in size of the full image increased the DoF because it changed the perceived sharpness of the image. The same is true in reverse – enlarging an image results in a shallower DoF.

What changes is, as the image is enlarged, it is easier for the eye to perceive the lack of focus. The reverse is true as well, the smaller the image size the sharper the image is going to appear to the human eye. But, the actual depth of field never changes, it's simply that the larger the image, the easier it is for the human eye to see that an object is not in focus. And, yes, viewing distance will make a difference in perceived depth of field. A billboard viewed from the street may appear sharp, but when viewed from three feet away, any lack of sharpness will become apparent. Depth of field doesn't magically change, it is simply a limitation of our own biology.

This is a correct statement:

Depth of field, detail, and magnification are fixed as soon as you press the shutter release. Cropping will not reveal anything that was not already in the image.
 

Jethro

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Jul 14, 2018
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I think the argument may be around accepted measures of DoF, which do take into account perceived DoF (and a standardised size etc), and which are useful if you are making comparisons between (eg) different sensor types and/or crops.
 
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Distinctly Average

EOS M6 Mark II
Sep 30, 2021
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I think the argument may be around accepted measures of DoF, which do take into account perceived DoF (and a standardised size etc), and which are useful if you are making comparisons between (eg) different sensor types and/or crops.
Thing is, does it really matter? Most photographers I know never think about it, or need to. Skills developed over time give us an ability to know what works. We just want to enjoy our hobby or profession. Always good to discuss these things though.
 
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neuroanatomist

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Jul 21, 2010
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Oh boy! We've been through this so many times.
Yes, because you and others continue failing to grasp the concept and persist in posting incorrect information.

I'd like to know what, other than lens aperture, distance to subject and focal length of the lens, is going to affect depth of field? Real depth of field, not perception of depth of field.

In this example the depth of field does not change.

What changes is, as the image is enlarged, it is easier for the eye to perceive the lack of focus. The reverse is true as well, the smaller the image size the sharper the image is going to appear to the human eye. But, the actual depth of field never changes, it's simply that the larger the image, the easier it is for the human eye to see that an object is not in focus. And, yes, viewing distance will make a difference in perceived depth of field. A billboard viewed from the street may appear sharp, but when viewed from three feet away, any lack of sharpness will become apparent. Depth of field doesn't magically change, it is simply a limitation of our own biology.
Depth of field is perception-dependent. DoF is commonly defined as, “The distance between the nearest and the farthest objects that are in acceptably sharp focus in an image.” The Oxford Dictionary makes it even more evident: “The distance between the nearest and the furthest objects that give an image judged to be in focus in a camera.”

Apparently you have a definition in your head that differs from the canonical one. Can you articulate your perception-independent definition of ‘real depth of field’? Or share an accurate mathematical expression of DoF that omits the CoC term?