Adapting MF lens to FF camera
Dec 3, 2018 10:18:13 #
My question is: If a medium format lens, say a Pentax 67 lens is adapted to a Nikon F mount FF camera is the lens still the same effective focal length and aperture? By effective I am referring to how when comparing FF to cropped sensor the effective focal length of a given lens is roughly increased by a factor of 1.5. Not trying to start a flame fest, just a simple question.
Dec 3, 2018 10:19:17 #
RWR
Loc: La Mesa, CA
DaveC1 wrote:
My question is: If a medium format lens, say a Pentax 67 lens is adapted to a Nikon F mount FF camera is the lens still the same effective focal length and aperture?
Yes.
Dec 3, 2018 10:31:00 #
DaveC1 wrote:
My question is: If a medium format lens, say a Pentax 67 lens is adapted to a Nikon F mount FF camera is the lens still the same effective focal length and aperture? By effective I am referring to how when comparing FF to cropped sensor the effective focal length of a given lens is roughly increased by a factor of 1.5. Not trying to start a flame fest, just a simple question.
Yes
Dec 3, 2018 10:41:29 #
Bob Locher
Loc: Southwest Oregon
Yup. The lens will have the effect of being a longer lens on your Nikon than it would on the MF Pentax. But if it is say a 150 mm lens, it is always a 150 mm lens no matter what camera it is mounted on.
Often such lenses will work very well indeed when mounted on a camera with a smaller sensor, since only the central part of the image is being used; most lenses are sharper at or near the center. However, the designer also may have made trade offs to get better coverage over the wider design format that could reduce center sharpness. Test to find out.
Often such lenses will work very well indeed when mounted on a camera with a smaller sensor, since only the central part of the image is being used; most lenses are sharper at or near the center. However, the designer also may have made trade offs to get better coverage over the wider design format that could reduce center sharpness. Test to find out.
Dec 3, 2018 12:26:46 #
DaveC1 wrote:
My question is: If a medium format lens, say a Pentax 67 lens is adapted to a Nikon F mount FF camera is the lens still the same effective focal length and aperture? By effective I am referring to how when comparing FF to cropped sensor the effective focal length of a given lens is roughly increased by a factor of 1.5. Not trying to start a flame fest, just a simple question.
A lens has always the same focal length, no matter on what camera you place it, and yet you're right, you have to consider the "crop factor", so a MF lens on a ff camera has a different field of view, than on a MF camera! You'll have to multiply your focal length by 0.something, depending on format! So, for example, if I take one of my 6x4.5 lenses, lets say, the 45-85mm and put it on my Canon 5D, it would compare to a 33.5-67mm in FF!
Dec 4, 2018 12:19:53 #
Dave, I do this often. I adapt my Zeiss lenses used with my Hasselblad to my Nikon FX cameras. The focal length doesn't change.
--Bob
--Bob
DaveC1 wrote:
My question is: If a medium format lens, say a Pentax 67 lens is adapted to a Nikon F mount FF camera is the lens still the same effective focal length and aperture? By effective I am referring to how when comparing FF to cropped sensor the effective focal length of a given lens is roughly increased by a factor of 1.5. Not trying to start a flame fest, just a simple question.
Dec 5, 2018 13:51:29 #
speters wrote:
A lens has always the same focal length, no matter on what camera you place it, and yet you're right, you have to consider the "crop factor", so a MF lens on a ff camera has a different field of view, than on a MF camera! You'll have to multiply your focal length by 0.something, depending on format! So, for example, if I take one of my 6x4.5 lenses, lets say, the 45-85mm and put it on my Canon 5D, it would compare to a 33.5-67mm in FF!
I just came across this topic again and was reading my reply and noticed, that I did not word it right. The mentioned lens, does indeed compare to a 33.5-67mm in ff frame, but that is used on a MF camera! I just wanted to correct myself, because it would be easy to misinterpret what I said! Sorry about that!
Dec 5, 2018 14:25:00 #
Thanks guys I think I have it figured out now.
It seems to me the way to look at this is: A 200mm lens is a 200mm lens. If that lens is used to illuminate a 120 size sensor (or film) it imprints an image that's approximately 57mm X 57mm (6x6.) If that same lens illuminates a 35mm sensor the image that is imprinted is approximately 20mm X 30mm. But the second image is only a portion of the original image, approximately 18% of the original 6X6 image in area. Now if we blow both images up to the same size print; the image from the 35mm size sensor will be magnified by a factor of somewhere around 2.85 times (57mm/20mm), give or take, since the two sensors have different aspect ratios. Its in the enlarging where the apparent extra magnification comes in.
It seems to me the way to look at this is: A 200mm lens is a 200mm lens. If that lens is used to illuminate a 120 size sensor (or film) it imprints an image that's approximately 57mm X 57mm (6x6.) If that same lens illuminates a 35mm sensor the image that is imprinted is approximately 20mm X 30mm. But the second image is only a portion of the original image, approximately 18% of the original 6X6 image in area. Now if we blow both images up to the same size print; the image from the 35mm size sensor will be magnified by a factor of somewhere around 2.85 times (57mm/20mm), give or take, since the two sensors have different aspect ratios. Its in the enlarging where the apparent extra magnification comes in.
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