Some pretty convincing evidence here..
http://www.have-camera-will-travel.com/field_reports/full_frame_vs_crop_sensor_-.html
http://www.have-camera-will-travel.com/field_reports/full_frame_vs_crop_sensor_-.html
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Full frame = more DOF just a myth?
- Thread starter greenLite
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erikstefan
Leading Member
To have the same "Field of View" the FF will have much thinner DOF
These pictures below are not of the same Field of View
Wrong comparison
If on 30D you use 105mm focal length then to get "the same Field of View" on 5D you have to use 168mm focal length, there you will have very thin DOF because of longer focal length needed to achieve the same Field of View.
These pictures below are not of the same Field of View
Wrong comparison
If on 30D you use 105mm focal length then to get "the same Field of View" on 5D you have to use 168mm focal length, there you will have very thin DOF because of longer focal length needed to achieve the same Field of View.
the shallower DOF of the Full Frame happens if you take photos with the same field of view. In this case this would have meant that the guy would have to move closer with the 5d, would have to focus closer, and thus would get hallow DOF at the same field of view.
best
georg
best
georg
Victor Engel
Veteran Member
Either:
Look at the two pictures with respect to what detail is in acceptable focus. On the 30D picture, I judge it to be from about 19 5/8 to 20 1/2. While the 5D image is essentially identical in content, it's smaller, so that makes what is blurred on the 30D actually acceptably in focus on the 5D image. I judge the acceptable range on the 5D image to be from 19 1/8 to about 20 7/8.
If the final image were bigger, my choices would be different. But the 5D would still have a greater DOF.
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- A different lens should have been used for each camera
- More attention paid to detail.
Look at the two pictures with respect to what detail is in acceptable focus. On the 30D picture, I judge it to be from about 19 5/8 to 20 1/2. While the 5D image is essentially identical in content, it's smaller, so that makes what is blurred on the 30D actually acceptably in focus on the 5D image. I judge the acceptable range on the 5D image to be from 19 1/8 to about 20 7/8.
If the final image were bigger, my choices would be different. But the 5D would still have a greater DOF.
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JackM
Veteran Member
Imagine taking a portrait of a person with a crop camera and an 85mm lens. Now imagine taking that lens and putting it on a full frame camera and taking the portrait again. In order to approximately duplicate the composition, you will have to move closer to the subject, thereby reducing DOF.
Similarly, if you were doing the above comparison using a zoom lens and standing the same distance from your subject for both cameras, you'd have to zoom in with the FF camera, again reducing DOF.
Of course a lens projects the same image and same DOF onto the focal plane regardless of sensor size. But the sensor size makes you use your lenses differently.
Similarly, if you were doing the above comparison using a zoom lens and standing the same distance from your subject for both cameras, you'd have to zoom in with the FF camera, again reducing DOF.
Of course a lens projects the same image and same DOF onto the focal plane regardless of sensor size. But the sensor size makes you use your lenses differently.
To get a one-to-one comparison of DOF, both cameras need to be shooting at the same distance from the point of focus, framing the same shot. Obviously, if a 30D is using a 105mm macro, and a 5D is using a 105mm macro, they are not going to be shooting from the same distance. To get the same framing, from the same shooting distance, the 30D would need to shoot at 65mm compared to the 5D using 105mm. That difference in focal length is obviously going to yield differing DOF between the two.
gdanmitchell
Veteran Member
It is true, though there are complicating factors.
Basically you need to compare lenses with different focal lengths that provide the same angle of view. In the real world that is how you would use the two formats.
The deeper DOF of the smaller sensor at a given angle of view and aperture is, to some extent, a bit offset by the fact that an higher magnification factor is needed to make a print of size X from the smaller format.
The world is a complicated place.
Dan
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Basically you need to compare lenses with different focal lengths that provide the same angle of view. In the real world that is how you would use the two formats.
The deeper DOF of the smaller sensor at a given angle of view and aperture is, to some extent, a bit offset by the fact that an higher magnification factor is needed to make a print of size X from the smaller format.
The world is a complicated place.
Dan
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Exactly. That's how you'd do it in the real world. You'd be standing at position, framing the shot at a distance, choosing your aperture, and taking the shot. Doing the exact same thing with a FF camera and an APS camera will deliver different DOFs between the two because the one thing that is different between the two is the focal length that has to be used to get the same framing and angle of view.
People who watch DOF and/or shot both formats know exactly what it is.
David Franklin
Veteran Member
Depends on what you're comparing it to. "Ful frame," compared to any smaller sensor sized camera, when shot with the same focal length lens at the same aperture, at a distance wherein the fields of view are equal, yields LESS depth-of-field than the smaller sensor camera. Or to put it another way, it yields a shallower depth-of-focus.
Here's another more detailed explanation of mine from another thread:
"The bigger the format, the shallower the depth-of-field will be at the same aperture showing the exact same field of view.
This question of depth-of-field differences with the same focal length lens on different format cameras is one that has been asked of me by dozens of assistants over the last 30 years, so I’ve had more experience answering it than have many others.
First, let me say that this question was much easier to answer when “newbs” could see the gross differences created by the vastly different film sizes that professionals used to use, such as from 35mm to 8”x10”, for example.
I’ll try my best to explain in a practical, non-mathematical way. Let’s say that you have a 50mm lens which, when shot on a 4”x5” view camera covers at least the whole 4’x5” film in the film plane. Now think of how much of that 20 square inches of film image created by that lens would be visible if it was focused on the same spot, at the same distance and asperture, but used in a 35mm camera – 1.5 square inches at the center of the 4”x5” image. What this means is obvious. A 50mm lens on a 4”x5” camera is a very extreme wide angle. On a 35mm camera, it is a “normal” lens. Theoretically, the same lens, shot at the same aperture, at the same point of focus would have identical depth of field. That’s true enough, but the image itself would be totally different; the 4”x5” image would show a vastly greater area of the available view than would the 35mm “crop.” This is the most important thing to understand. What most people want to know is not whether the depth-of-field of both the 4”x5” crop and the 35mm crop would be identical while showing a radically different image altogether., but what the depth-of-field differences would be if one were to take images which were identical in their fields-of-view with both formats, using the same lens, focused on the same spot, at the same aperture, from whatever vantage point would be necessary to obtain equal points of view. This is the crux of the matter. In order to show the same field of view as the 4”x5” film, the 35mm camera image would have to be a great deal further away from the point of focus in the scene. When the 35mm camera is moved back by the proper amount to show that wider field, its focus is no longer (warning, just for example, not mathematically accurate) at, let’s say, 1 foot away, but would then be 5 feet away from that same point of focus. Practical depth-of-field decreases as the camera-to-focused-subject distance decreases and vice versa. The result is obvious to any viewer. The depth-of-field of an image take when focused at 12 inches is vastly smaller than one taken at 5 feet. An image taken with same focal length lens, focused on the same point, at the same aperture, producing identical fields of view (the only meaningful comparison - anything else is apples-to-oranges), will always yield less depth-of-field in the image taken with the larger format camera than that taken by a smaller format camera using the same criteria.
While the visible differences between 4”x5” and 35mm are greater than those between 35mm and APS size formats, the principle still applies and is quite obvious to most interested observers. That’s it. I hope this makes it clearer to some of you who may not have quite yet understood this."
Regards,
David
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Keep learning; share knowledge; think seriously about outcomes; seek wisdom.
Here's another more detailed explanation of mine from another thread:
"The bigger the format, the shallower the depth-of-field will be at the same aperture showing the exact same field of view.
This question of depth-of-field differences with the same focal length lens on different format cameras is one that has been asked of me by dozens of assistants over the last 30 years, so I’ve had more experience answering it than have many others.
First, let me say that this question was much easier to answer when “newbs” could see the gross differences created by the vastly different film sizes that professionals used to use, such as from 35mm to 8”x10”, for example.
I’ll try my best to explain in a practical, non-mathematical way. Let’s say that you have a 50mm lens which, when shot on a 4”x5” view camera covers at least the whole 4’x5” film in the film plane. Now think of how much of that 20 square inches of film image created by that lens would be visible if it was focused on the same spot, at the same distance and asperture, but used in a 35mm camera – 1.5 square inches at the center of the 4”x5” image. What this means is obvious. A 50mm lens on a 4”x5” camera is a very extreme wide angle. On a 35mm camera, it is a “normal” lens. Theoretically, the same lens, shot at the same aperture, at the same point of focus would have identical depth of field. That’s true enough, but the image itself would be totally different; the 4”x5” image would show a vastly greater area of the available view than would the 35mm “crop.” This is the most important thing to understand. What most people want to know is not whether the depth-of-field of both the 4”x5” crop and the 35mm crop would be identical while showing a radically different image altogether., but what the depth-of-field differences would be if one were to take images which were identical in their fields-of-view with both formats, using the same lens, focused on the same spot, at the same aperture, from whatever vantage point would be necessary to obtain equal points of view. This is the crux of the matter. In order to show the same field of view as the 4”x5” film, the 35mm camera image would have to be a great deal further away from the point of focus in the scene. When the 35mm camera is moved back by the proper amount to show that wider field, its focus is no longer (warning, just for example, not mathematically accurate) at, let’s say, 1 foot away, but would then be 5 feet away from that same point of focus. Practical depth-of-field decreases as the camera-to-focused-subject distance decreases and vice versa. The result is obvious to any viewer. The depth-of-field of an image take when focused at 12 inches is vastly smaller than one taken at 5 feet. An image taken with same focal length lens, focused on the same point, at the same aperture, producing identical fields of view (the only meaningful comparison - anything else is apples-to-oranges), will always yield less depth-of-field in the image taken with the larger format camera than that taken by a smaller format camera using the same criteria.
While the visible differences between 4”x5” and 35mm are greater than those between 35mm and APS size formats, the principle still applies and is quite obvious to most interested observers. That’s it. I hope this makes it clearer to some of you who may not have quite yet understood this."
Regards,
David
--
Keep learning; share knowledge; think seriously about outcomes; seek wisdom.
I can't believe people are actually debating this!!!!!!!!! With full frame you go in closer with the same lens to get the same stuff in the picture. Going in closer with the same aperture but with the same area of coverage (which you get with the FF) gives you less depth of field.
dave_melb_aus
Member
Michael Reichmann has already written an article with experimental test shots on his site if you don't have time to study this by yourself.
http://luminous-landscape.com/tutorials/understanding-series/dof.shtml
http://luminous-landscape.com/tutorials/dof2.shtml
http://luminous-landscape.com/tutorials/understanding-series/dof.shtml
http://luminous-landscape.com/tutorials/dof2.shtml
Karl Gohl
Leading Member
Here's an explanation I posted in the Rebel forum a few weeks ago. I'm reposting because some thought it sums up the issue fairly well:
It all depends on what you hold constant. In the following I will assume that the camera location and lens aperture are constant.
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Karl (see Plan for equipment list)
It all depends on what you hold constant. In the following I will assume that the camera location and lens aperture are constant.
- Same actual focal length, same amount of enlargement (e.g. both FF and crop enlarge the image 8x bigger than the size of their sensor, so approx 8x12" for FF, 5x7.5 for 1.6 crop) then DOF is exactly the same since the crop sensor print is just a crop of the FF print -- you could lay it down on the middle of the FF print and see no difference. BTW: some will argue that the DOF must be the same since the crop camera just crops the image you would get with a FF. That's fine, as long as they are clear that they are talking about constant focal length and constant enlargement amount.
- Same focal length, same print size. The crop camera shot has been enlarged more, so its DOF is about a stop less.
- Same scene imaged onto the sensor (i.e. crop camera uses a shorter focal length such that the exact same scene is projected onto its sensor as on the FF camera), same amount of enlargement: crop camera shot will have about 2 stops more DOF.
- Same scene imaged onto the sensor, same print size: Crop camera shot gains about 2 stops of DOF due to shorter focal length but loses about 1 stop due to greater enlargement yielding about 1 stop more total DOF.
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Karl (see Plan for equipment list)
Indeed he has however, just like his use of COF as an acronym for Circle of Confusion, a lot of it is COC.
Not least of which is the replication of the myth that DOF extends from 1/3 in front of focus to 2/3 behind it, so you have twice as much DOF behind focus as in front of it. The law of optics that Reichmann misquotes is that this is generally false and only true when focussed on half the hyperfocal distance. The hyperfocal distance itself proves Reichmann's claim is myth - behind you have focus to infinity, which is more than twice anything!
Sadly, its only one of several factual errors in his DOF articles.
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Its RKM
Victor Engel
Veteran Member
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erikstefan
Leading Member
Notes:
Reichmann is right, but doesn't explicitly explain about the difference between Crop sensor and Full Frame. You have to turn around the logic to arrive to the difference between FF and APS-C
For this thread Reichmann explanation says that me and GeorgL will have the same DOF on 5D,
where I said on 5D you have to use longer focal length (168mm) to get the same FoV
http://forums.dpreview.com/forums/read.asp?forum=1032&message=33016929
while GeorgL said if using the same focal length 105mm on 5D you have to to move closer to the object to get the same FoV
http://forums.dpreview.com/forums/read.asp?forum=1032&message=33017048
according to Reichmann me and GeorgL will have the same DOF on 5D.
This DOF on 5D is shallower than APS-C with the same FoV same aperture.
And if you calculate the DOF difference in this way between FF and APS-C you will be surpsired how huge the difference is ( http://www.dofmaster.com/dofjs.html )
erikstefan
Leading Member
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