faris
Well-known
would give you the same dof on an M8 as on a M7?
What and how are they related?
Thanks.
What and how are they related?
Thanks.
what FL and aperture...
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user237428934
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http://www.dofmaster.com/doftable.html
Choose film and then choose M8 from the list and you can compare for yourself.
faris
Well-known
Tom, thanks a lot.
hiromu
Established
DOF does not change if you use with M7 or M8 AS LONG AS you shoot from the same distance.
It changes IF you try to frame your object in the same way. Since the film/sensor size is different, to frame your object in the same way,
1) you have to use shorter lens with M8 if you keep the distance the same,
or
2) you have to come closer with M7 when using the same lens.
If you do either 1 or 2, then DOF will be different for M7 and M8.
Hiromu
It changes IF you try to frame your object in the same way. Since the film/sensor size is different, to frame your object in the same way,
1) you have to use shorter lens with M8 if you keep the distance the same,
or
2) you have to come closer with M7 when using the same lens.
If you do either 1 or 2, then DOF will be different for M7 and M8.
Hiromu
Jeff S
Well-known
But, if you shoot from the same distance, then the DOF is also different. See attached tutorial and plug in same information in DOF calculator at end, varying only the sensor/film size, i.e., 35mm vs 1.3 crop...http://www.cambridgeincolour.com/tutorials/depth-of-field.htm
Jeff
jaapv
RFF Sponsoring Member.
Anyway, Leica claims in all manuals that the DOF is the same. I suppose they know a thing or two about optics.🙄
Jeff S
Well-known
No doubt, so please explain above. I'd be interested to know where I, or Cambridge tutorial, got this wrong....seriously.
Jef
Papa Smurf
Established
Rehash of an old issue
Rehash of an old issue
jaapy is correct, the DOF is a function of lens aperture, focal length of lens and the focus distance, not the image size on the "receptor", be it film or sensor. However, hiromu is also correct, to a point, we see differently through a non full frame digital viewfinder than we do through a full frame film view finder. If you doubt me, then take any DSLR and a compatible film slr, with each stand in one spot and view a nearby object, first with the DSLR and then the film SLR both cameras using the exact same lens at the same aperture and the same focus distance. You will see a different framing of the object. In this example, the DOF would be exactly the same as it was the same lens at the same aperture and the same focus distance! However, if we were to move closer with the film SLR or farther away with the Dslr in order to achieve the same framing through the viewfinder as viewed with the other camera, we would have changed one of the variables in determining the DOF; therefore the equation must remain true so the DOF will have changed, albeit slightly.
This issue was argued extensively on another forum dedicated to one lens mount compatible with the brand's film SLRs and DSLRs. It is hard to understand, but easy to demonstrate if you perform my little experiment. DOF is a physical function of the mathematics of the lens design, not the recording method. 😉
Rehash of an old issue
jaapy is correct, the DOF is a function of lens aperture, focal length of lens and the focus distance, not the image size on the "receptor", be it film or sensor. However, hiromu is also correct, to a point, we see differently through a non full frame digital viewfinder than we do through a full frame film view finder. If you doubt me, then take any DSLR and a compatible film slr, with each stand in one spot and view a nearby object, first with the DSLR and then the film SLR both cameras using the exact same lens at the same aperture and the same focus distance. You will see a different framing of the object. In this example, the DOF would be exactly the same as it was the same lens at the same aperture and the same focus distance! However, if we were to move closer with the film SLR or farther away with the Dslr in order to achieve the same framing through the viewfinder as viewed with the other camera, we would have changed one of the variables in determining the DOF; therefore the equation must remain true so the DOF will have changed, albeit slightly.
This issue was argued extensively on another forum dedicated to one lens mount compatible with the brand's film SLRs and DSLRs. It is hard to understand, but easy to demonstrate if you perform my little experiment. DOF is a physical function of the mathematics of the lens design, not the recording method. 😉
peterm1
Veteran
As a couple have said depth of field is determined by lens aperture, focal length of lens and the focus distance. A key determinant is the "size of the hole" if I can put it that way. Many smaller pocket digitals use tiny lenses to match their tiny sensor. If the smaller lens is designed with a physically smaller aperture at any f stop (remember f stop is a relative measure not an absolute measure of size of the hole) then it will give a greater depth of field than a lens used on a 35mm format (assuming the same focal length) - but of course you ARE using lenses for the 35mm format on a M8 even though the sensor is smaller. Hence no change in depth of field for any given focal length.
Papa Smurf
Established
Confusing the circle of confusion.
Confusing the circle of confusion.
If I remember correctly from the aforementioned other forum. Online DOF calculators such as the one you refer to use a smaller circle of confusion in the digital lens calculations than in the film calculations. Notice that each crop size also returns different numbers. They do that because of the difference in the image size with film versus a digital non full frame sensors. This is done to compensate for the apparent change in DOF when the images are viewed at the same enlargement. The lens formula does not change when they are designing a full frame lens for film or digital. What does change is some of the compromises in the design. Digital lens must suppress the sensor reflection of itself. The mirror in the mirror in the mirror on and on. Film does not reflect upon the rear lens elements to the degree that a digital sensor does. 😕
Confusing the circle of confusion.
If I remember correctly from the aforementioned other forum. Online DOF calculators such as the one you refer to use a smaller circle of confusion in the digital lens calculations than in the film calculations. Notice that each crop size also returns different numbers. They do that because of the difference in the image size with film versus a digital non full frame sensors. This is done to compensate for the apparent change in DOF when the images are viewed at the same enlargement. The lens formula does not change when they are designing a full frame lens for film or digital. What does change is some of the compromises in the design. Digital lens must suppress the sensor reflection of itself. The mirror in the mirror in the mirror on and on. Film does not reflect upon the rear lens elements to the degree that a digital sensor does. 😕
Jeff S
Well-known
jaapv
RFF Sponsoring Member.
You'd have to ask Leica for an explanation of their statement. I am not their spokesman.
jaapv
RFF Sponsoring Member.
Not quite. There is one more factor. As film has a thickness the image points are three dimensional within a semi-opaque medium (film emulsion) that give less defined COC-s and COC-s that are deformed elipsoid towards the cornenrs. Thus the sensor will give a steeper DOF gradient, giving the impression of a more narrow DOF.
Jeff S
Well-known
No need...the other helpful posts above answered my specific question about the online DOF charts. I never had a question about Leica. As I recall, you're the one who used Leica (snidely) as your source of information.
Jeff
Last edited:
Papa Smurf
Established
You are correct.
You are correct.
You are correct, although there is another factor on why the digital sensor appears to have a narrower DOF. Because it is less than full frame, the sensor only sees the light coming through the center two thirds or so of the lens. Manufacturers are much better at getting the center of the lens nearly exact in the convergence of all light waves to one point, a very small CoC. O.K., before I am flamed on that one, the light falling on any one point of the film or sensor comes from all over the lens, not just one small portion that is why a tiny scratch usually doesn't show up in the image. But the bulk of the light falling upon the center of the film or sensor does pass through the center of the lens.
Back to the original OP question, the OP needs to go to an online DOF calculator and choose a lens focal length, aperture, and focus distance that he will most likely encounter in the real world. Start with the M7 if that is what he has been using. Write done the numbers, then change the menu to the M8's crop factor; I believe someone said 1.6. Now start adjusting the aperture by 1/3 increments until the new calculations approximate the numbers of the M7. Keep in mind that the lens has not changed, just our perception of the resulting image. This is all very confusing and not really necessary unless one is doing Macro photography. Actually, I am usually looking for the OoF, not in focus, and how it isolates the subject. On a SLR one would just have to it the preview button, too bad that our rangefinders do not have a preview button. Maybe that could be the last frontier in rangefinder evolution! Leica, are you listening?
You are correct.
You are correct, although there is another factor on why the digital sensor appears to have a narrower DOF. Because it is less than full frame, the sensor only sees the light coming through the center two thirds or so of the lens. Manufacturers are much better at getting the center of the lens nearly exact in the convergence of all light waves to one point, a very small CoC. O.K., before I am flamed on that one, the light falling on any one point of the film or sensor comes from all over the lens, not just one small portion that is why a tiny scratch usually doesn't show up in the image. But the bulk of the light falling upon the center of the film or sensor does pass through the center of the lens.
Back to the original OP question, the OP needs to go to an online DOF calculator and choose a lens focal length, aperture, and focus distance that he will most likely encounter in the real world. Start with the M7 if that is what he has been using. Write done the numbers, then change the menu to the M8's crop factor; I believe someone said 1.6. Now start adjusting the aperture by 1/3 increments until the new calculations approximate the numbers of the M7. Keep in mind that the lens has not changed, just our perception of the resulting image. This is all very confusing and not really necessary unless one is doing Macro photography. Actually, I am usually looking for the OoF, not in focus, and how it isolates the subject. On a SLR one would just have to it the preview button, too bad that our rangefinders do not have a preview button. Maybe that could be the last frontier in rangefinder evolution! Leica, are you listening?
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