Iyfjky

Question

To keep the conversation simple, please focus only on native lens design for the mount.

So with the recent Nikon mirrorless announcement, Nikon has been touting the bigger mount. I am no expert in this area so I was wondering if someone would help me understand this topic.

Nikon indicated that the bigger mount is there so that lens can be made faster. Sony disagree. Based on products in the past, such as the current L series canon 50mm 1.2, seem like Nikon statement is false.

So that's both side of the argument. I don't have enough understanding in this matter to figure out who is right, and who is bullshitting.

Would someone with enough understanding explain who is wrong and who is right, and if there is/area actual benefit to having a larger mount when it comes to getting more lights to the sensor via faster lens?

Control lens. 85mm f/1.0.

Does having a larger mount mean that the design of this lens could be less complicated compare to the design of the same lens on a smaller mount? And if the lens design is less complicated, that mean cost can also be lowered.

Thanks.

"focus only on native lens design for the mount"Ã¢Â€Â‚Ã¢Â€Â“Ã¢Â€Â‚Which mount?Ã¢Â€Â‚You mention Sony, Nikon, and Canon, who each have their own mount. — 6 hours ago

Michael Clark 121k7137339 · Answer 1 · 2018-09-27 02:44:11Z

First: Sony doesn't necessarily disagree with Nikon's claim. It's just that Sony designed their 'E' mount with a throat diameter of 46.1 millimeters at a time when it appeared it would be an APS-C only mount for the NEX series of compact mirrorless ILCs.

Sony later made the decision to move into full frame territory using the all-electronic 'E' mount, rather than either using the existing mechanical 'A' mountÃ‚Â¹ that dated all the way back to Minolta film cameras or creating yet another new mount for their FF mirrorless cameras. The 46.1 mm throat diameter of the 'E' mount is just large enough to accommodate the 43.27 mm diagonal of a 36x24 mm FF sensor.

Second: The all-electronic Canon EOS 'EF' mount, introduced in 1987, has a throat diameter of 54 mm. The existence of a 50mm f/1.2 lens in the Canon EF mount with its 54mm throat diameter does nothing to disprove Nikon's claim that their new 55 mm wide 'Z' mount allows better lens design than their previous 'F' mount, which had a narrow throat diameter of only 44 mm.

Basically, since 1987 when Canon introduced the 'EF' mount with a 44 mm registration distance and a 54mm throat diameter, Nikon has been technically limited from matching some of Canon's lens designs due to their own 46.5 mm registration distance and narrower 44 mm throat diameter.Ã‚Â² Similarly, with the introduction of the Sony 'E' mount in 2010 and the application of it to FF cameras with the introduction of the Sony ÃŽÂ±7 series of cameras in late 2013, Nikon 'F' cameras (and Canon EOS cameras as well) were at a disadvantage with regard to designing very wide angle, very wide aperture lenses that can take advantages of the shorter registration distance to both simplify design, reduce size/weight, and match or improve lens performance in a smaller package.

Nikon is touting the newer throat diameter and much shorter registration distance of the 'Z' mount because it is one millimeter wider than the Canon EF mount has been since introduced in 1987 and two millimeters shorter than the Sony 'E' mount has been since introduced in 2010. It's also 11 mm wider and 30.5 mm shorter than their own 'F' mount.

For shorter focal length lenses with wider apertures, a larger throat diameter allows larger exit pupils. A shorter registration distance allows shorter focal lengths without needing to resort to a complex retrofocus design to make lenses with focal lengths shorter than the registration distance. Both of these factors combined mean that larger rear lens elements can be positioned closer to the imaging sensor. This allows for lens designs not possible using narrower throat diameters placed at greater distances from the camera's image plane.

Control lens. 85mm f/1.0

With an 85mm focal length lens, the difference between 16mm and 46.5mm registration distance is not really a factor at all because 85mm is considerably longer than even the 46.5mm registration distance of the Nikon 'F' mount. When one looks, for example, at 85mm lenses for the Sony E-mount and compares them to 85mm lenses with the same maximum aperture for the Canon EF mount or Nikon F mount, it's pretty easy to see that the lenses are about 30 millimeters longer for the 'E' mount to make up for the roughly 30 millimeters shorter mounting flange. The rear elements of the 85mm lenses for the Sony 'E' mount are about 30mm more recessed into the lens.

The wider throat diameter is a factor, because it allows light striking the edge of the imaging sensor to strike it at a more perpendicular angle than a narrower throat diameter would. This increases the amount of light falling on each photosite in the same way that each square meter of ground on the surface of the Earth receives more light/energy from the sun when it is high overhead than when it is low on the horizon. In fact, it would be even more analogous to how much sunlight, based on the angle of the sun, would strike a one meter square on the Earth's surface with a solid 1-2 meter high fence around it, since the pixel wells on typical ILC sensors have depth that usually exceeds their own width.

_{Ã‚Â¹ The Minolta/Sony 'A' mount had a 44.5 mm registration distance and a 49.7 mm throat diameter.}

_{Ã‚Â² The previous Canon 'FL' and 'FD' mounts had 48 mm throat diameters that were 4 mm wider and sat 4 mm closer to the film than the Nikon 'F' mount, giving them a slight advantage when designing very large aperture lenses in medium focal length ranges. That's one reason Nikon's 58mm prime could be designed differently than their 50mm primes. The 3.5mm difference between 46.5mm and 50mm is not quite enough room to fit all of the lens elements needed for a higher quality yet simply designed 50mm lens.}

scottbb 17.5k75184 · Answer 2 · 2018-09-27 04:41:11Z

Using your thumb and forefinger on each hand, make a finger frame, and hold it out at arms length.

enter image description here

Now imagine that your entire field of view is limited by the bounds of this finger frame. Anything outside of the frame is not visible to you.

If you wanted to see a larger (wider) field of view, you have two options:

Move the finger frame closer to your eye. In fact, rest the finger frame on your forehead and nose. You'll still see the bounds of the frame, but you'll be able to see a large field inside the frame.

This is the analog of moving from the > 40Ã‚Â mm flange depth of DSLRs to the much shorter 16Ã¢Â€Â“20Ã‚Â mm flange depth of mirrorless cameras.

Increase the size of the frame by moving your hands apart.

This is the analog of increasing the flange mount size.

Nikon has did both with its Z-mount system. But really, it had no choice. Nikon had to do both:

Introducing a viable mirrorless camera system is required for any manufacturer to be competitive in today's camera market. Nikon did not have one.

Nikon's existing F-mount system dated back to the 1950s. Its 45Ã‚Â mm throat imposed constraints on lens design, that are much more relaxed with the 55Ã‚Â mm throat of the Z-mount.

Nikon indicated that the bigger mount is there so that lens can be made faster. Sony disagree.

No, Sony doesn't disagree. Yes, Sony's E-mount throat diameter of 46.1 is among the smallest of MILC lens mount throats. But that's because it was initially designed for APS-C -sized sensors, with a possible eye towards full-frame sensors. They simply didn't design for benefits of large throat diameters that might ease lens design in the future, because they were focused on the benefits of small camera bodies in 2010.

Based on products in the past, such as the current L series canon 50mm 1.2, seem like Nikon statement is false.

Nikon's Z-mount introduction accompanied by an unimpressive lens lineup didn't disprove the benefits of a large throat diameter; it merely shows they didn't take advantage of the possibilities their new mount opened up to them.

The primary benefit of a large throat diameter on a short-flange distance camera body is not in designing an 85Ã‚Â mm Ã†Â’/1.0 lens. The main benefit will be when (if) they want to introduce a wide angle fast lens, perhaps a 14Ã‚Â mm Ã†Â’/1.4. Wide angle lenses in particular have been limited on DSLR bodies due to the need to use retrofocal optics to achieve the short focal length and wide angle of view. See also:

Why do wide angle prime lenses have relatively small apertures?

Why are wide-angle lenses so much more expensive?

Nikon's announced Z-mount Noct 58Ã‚Â mm Ã†Â’/0.95, is an example of what they can do with the wide mount that they couldn't do with the F-mount. Nikon's previous fast champion, the 58Ã‚Â mm Ã†Â’/1.2 Noct-Nikkor, had a rear element that was pushed to the very edge of its bayonet boundary. The rear glass even had a groove cut into a portion of its circumference, to accommodate the aperture linkage lever:

enter image description here

Had the F-mount throat been 55Ã‚Â mm rather than 45Ã‚Â mm, it's not likely they would have produced a 58Ã‚Â mm lens substantially faster than the Ã†Â’/1.2 at the time. But they certainly would have had the room to fit both the rear element and the aperture linkage lever without having to cram them together.

It's worth clarifying that a bit. There is a point at which the light from the lens crosses in both directions (hence the need for a pentaprism), at which the throat width could be essentially zero, and you would still get an image (ignoring that the mount would break easily). A larger rear lens element isn't precluded by a small flange size, but it requires either moving it farther away from the flange so the sensor can "see" the whole thing (retrofocal), or moving the flange closer to the sensor, which breaks lens compatibility anyway, so you might as well make the throat bigger. — 1 hour ago
You can demonstrate that by making circles with both hands, looking through one at the other. As you move the close one (the flange) closer to your eye, you can see more of the farther one (the rear element), and as you move the rear element farther away, you also see more of it. — 1 hour ago
@dgatwood I don't understand your point re: pentaprism. The pentaprism has nothing to do with capturing an image; it only is useful for seeing through the viewfinder. — 1 hour ago
The rays cross between the lens and the sensor, which is why DSLRs require a pentaprism (or pentamirror) to prevent the viewfinder image from being upside down and backwards. — 1 hour ago
@dgatwood Rays do not usually cross between the rear of the last lens element and the sensor in a compound lens such as we are discussing. The 'crossover point' is generally inside the lens in front of the rear group. With a simple single lens, it would be exactly halfway between the lens and the sensor. With a (non-retrofocus design) compound lens it is usually still somewhere in the vicinity of half the lens' focal length in front of the sensor. With a lens that uses a retrofocus design it is usually even further forward than half the focal length from the sensor. — 24 mins ago

Michael Clark 121k7137339 · Answer 3 · 2018-09-27 02:44:11Z

First: Sony doesn't necessarily disagree with Nikon's claim. It's just that Sony designed their 'E' mount with a throat diameter of 46.1 millimeters at a time when it appeared it would be an APS-C only mount for the NEX series of compact mirrorless ILCs.

Sony later made the decision to move into full frame territory using the all-electronic 'E' mount, rather than either using the existing mechanical 'A' mountÃ‚Â¹ that dated all the way back to Minolta film cameras or creating yet another new mount for their FF mirrorless cameras. The 46.1 mm throat diameter of the 'E' mount is just large enough to accommodate the 43.27 mm diagonal of a 36x24 mm FF sensor.

Second: The all-electronic Canon EOS 'EF' mount, introduced in 1987, has a throat diameter of 54 mm. The existence of a 50mm f/1.2 lens in the Canon EF mount with its 54mm throat diameter does nothing to disprove Nikon's claim that their new 55 mm wide 'Z' mount allows better lens design than their previous 'F' mount, which had a narrow throat diameter of only 44 mm.

Basically, since 1987 when Canon introduced the 'EF' mount with a 44 mm registration distance and a 54mm throat diameter, Nikon has been technically limited from matching some of Canon's lens designs due to their own 46.5 mm registration distance and narrower 44 mm throat diameter.Ã‚Â² Similarly, with the introduction of the Sony 'E' mount in 2010 and the application of it to FF cameras with the introduction of the Sony ÃŽÂ±7 series of cameras in late 2013, Nikon 'F' cameras (and Canon EOS cameras as well) were at a disadvantage with regard to designing very wide angle, very wide aperture lenses that can take advantages of the shorter registration distance to both simplify design, reduce size/weight, and match or improve lens performance in a smaller package.

Nikon is touting the newer throat diameter and much shorter registration distance of the 'Z' mount because it is one millimeter wider than the Canon EF mount has been since introduced in 1987 and two millimeters shorter than the Sony 'E' mount has been since introduced in 2010. It's also 11 mm wider and 30.5 mm shorter than their own 'F' mount.

For shorter focal length lenses with wider apertures, a larger throat diameter allows larger exit pupils. A shorter registration distance allows shorter focal lengths without needing to resort to a complex retrofocus design to make lenses with focal lengths shorter than the registration distance. Both of these factors combined mean that larger rear lens elements can be positioned closer to the imaging sensor. This allows for lens designs not possible using narrower throat diameters placed at greater distances from the camera's image plane.

Control lens. 85mm f/1.0

With an 85mm focal length lens, the difference between 16mm and 46.5mm registration distance is not really a factor at all because 85mm is considerably longer than even the 46.5mm registration distance of the Nikon 'F' mount. When one looks, for example, at 85mm lenses for the Sony E-mount and compares them to 85mm lenses with the same maximum aperture for the Canon EF mount or Nikon F mount, it's pretty easy to see that the lenses are about 30 millimeters longer for the 'E' mount to make up for the roughly 30 millimeters shorter mounting flange. The rear elements of the 85mm lenses for the Sony 'E' mount are about 30mm more recessed into the lens.

The wider throat diameter is a factor, because it allows light striking the edge of the imaging sensor to strike it at a more perpendicular angle than a narrower throat diameter would. This increases the amount of light falling on each photosite in the same way that each square meter of ground on the surface of the Earth receives more light/energy from the sun when it is high overhead than when it is low on the horizon. In fact, it would be even more analogous to how much sunlight, based on the angle of the sun, would strike a one meter square on the Earth's surface with a solid 1-2 meter high fence around it, since the pixel wells on typical ILC sensors have depth that usually exceeds their own width.

_{Ã‚Â¹ The Minolta/Sony 'A' mount had a 44.5 mm registration distance and a 49.7 mm throat diameter.}

_{Ã‚Â² The previous Canon 'FL' and 'FD' mounts had 48 mm throat diameters that were 4 mm wider and sat 4 mm closer to the film than the Nikon 'F' mount, giving them a slight advantage when designing very large aperture lenses in medium focal length ranges. That's one reason Nikon's 58mm prime could be designed differently than their 50mm primes. The 3.5mm difference between 46.5mm and 50mm is not quite enough room to fit all of the lens elements needed for a higher quality yet simply designed 50mm lens.}

scottbb 17.5k75184 · Answer 4 · 2018-09-27 04:41:11Z

Using your thumb and forefinger on each hand, make a finger frame, and hold it out at arms length.

enter image description here

Now imagine that your entire field of view is limited by the bounds of this finger frame. Anything outside of the frame is not visible to you.

If you wanted to see a larger (wider) field of view, you have two options:

Move the finger frame closer to your eye. In fact, rest the finger frame on your forehead and nose. You'll still see the bounds of the frame, but you'll be able to see a large field inside the frame.

This is the analog of moving from the > 40Ã‚Â mm flange depth of DSLRs to the much shorter 16Ã¢Â€Â“20Ã‚Â mm flange depth of mirrorless cameras.

Increase the size of the frame by moving your hands apart.

This is the analog of increasing the flange mount size.

Nikon has did both with its Z-mount system. But really, it had no choice. Nikon had to do both:

Introducing a viable mirrorless camera system is required for any manufacturer to be competitive in today's camera market. Nikon did not have one.

Nikon's existing F-mount system dated back to the 1950s. Its 45Ã‚Â mm throat imposed constraints on lens design, that are much more relaxed with the 55Ã‚Â mm throat of the Z-mount.

Nikon indicated that the bigger mount is there so that lens can be made faster. Sony disagree.

No, Sony doesn't disagree. Yes, Sony's E-mount throat diameter of 46.1 is among the smallest of MILC lens mount throats. But that's because it was initially designed for APS-C -sized sensors, with a possible eye towards full-frame sensors. They simply didn't design for benefits of large throat diameters that might ease lens design in the future, because they were focused on the benefits of small camera bodies in 2010.

Based on products in the past, such as the current L series canon 50mm 1.2, seem like Nikon statement is false.

Nikon's Z-mount introduction accompanied by an unimpressive lens lineup didn't disprove the benefits of a large throat diameter; it merely shows they didn't take advantage of the possibilities their new mount opened up to them.

The primary benefit of a large throat diameter on a short-flange distance camera body is not in designing an 85Ã‚Â mm Ã†Â’/1.0 lens. The main benefit will be when (if) they want to introduce a wide angle fast lens, perhaps a 14Ã‚Â mm Ã†Â’/1.4. Wide angle lenses in particular have been limited on DSLR bodies due to the need to use retrofocal optics to achieve the short focal length and wide angle of view. See also:

Why do wide angle prime lenses have relatively small apertures?

Why are wide-angle lenses so much more expensive?

Nikon's announced Z-mount Noct 58Ã‚Â mm Ã†Â’/0.95, is an example of what they can do with the wide mount that they couldn't do with the F-mount. Nikon's previous fast champion, the 58Ã‚Â mm Ã†Â’/1.2 Noct-Nikkor, had a rear element that was pushed to the very edge of its bayonet boundary. The rear glass even had a groove cut into a portion of its circumference, to accommodate the aperture linkage lever:

enter image description here

Had the F-mount throat been 55Ã‚Â mm rather than 45Ã‚Â mm, it's not likely they would have produced a 58Ã‚Â mm lens substantially faster than the Ã†Â’/1.2 at the time. But they certainly would have had the room to fit both the rear element and the aperture linkage lever without having to cram them together.

It's worth clarifying that a bit. There is a point at which the light from the lens crosses in both directions (hence the need for a pentaprism), at which the throat width could be essentially zero, and you would still get an image (ignoring that the mount would break easily). A larger rear lens element isn't precluded by a small flange size, but it requires either moving it farther away from the flange so the sensor can "see" the whole thing (retrofocal), or moving the flange closer to the sensor, which breaks lens compatibility anyway, so you might as well make the throat bigger. — 1 hour ago
You can demonstrate that by making circles with both hands, looking through one at the other. As you move the close one (the flange) closer to your eye, you can see more of the farther one (the rear element), and as you move the rear element farther away, you also see more of it. — 1 hour ago
@dgatwood I don't understand your point re: pentaprism. The pentaprism has nothing to do with capturing an image; it only is useful for seeing through the viewfinder. — 1 hour ago
The rays cross between the lens and the sensor, which is why DSLRs require a pentaprism (or pentamirror) to prevent the viewfinder image from being upside down and backwards. — 1 hour ago
@dgatwood Rays do not usually cross between the rear of the last lens element and the sensor in a compound lens such as we are discussing. The 'crossover point' is generally inside the lens in front of the rear group. With a simple single lens, it would be exactly halfway between the lens and the sensor. With a (non-retrofocus design) compound lens it is usually still somewhere in the vicinity of half the lens' focal length in front of the sensor. With a lens that uses a retrofocus design it is usually even further forward than half the focal length from the sensor. — 24 mins ago

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