Nikon has led the way in designing exotic glass for its mirrorless Z mount, but is this just a precursor to offering a medium format camera?
In an earlier post, I queried the potential obsolescence of the Sony E-mount. The E-mount was born from the "bonfire of the mirrorless" at the turn of the decade when Olympus and Panasonic (through the Micro Four Thirds group) led the charge to remove the optical viewfinder and with it, the mirror box. Manufacturers saw the potential, and within three years, almost everyone had released a new system (Pentax went one better and released two!). However, what was odd about this dramatic surge of investment and innovation — driven and funded by the mass sales of compact cameras — was that nobody really knew who was going to buy these systems!
Every new system required a new lens mount, and these have two key physical parameters: throat diameter and flange distance. Using these and a little trigonometry, you can calculate the maximum angle of incidence of light on to the sensor; the greater the angle, the more effective the mount. In particular, with no mirror box, the flange distance can be significantly reduced, bringing the mount closer to the sensor and increasing the incidence angle; this allows for innovative lens designs. It's worth remembering that Canon's EF mount long played to the strength of a large throat diameter, while Leica's rangefinder M (which didn't have a mirror box) had a small flange distance.
It's worth stating that Nikon has made great play of having designed the most competitive full-frame (FF) mount in the form of the Z: with a 55 mm internal diameter and 16 mm flange distance (44° incidence angle), it stands head and shoulders above the competition. For comparison, the Canon RF (54 mm and 20 mm) and Sony E (46.1 mm and 18 mm) have incidence angles of 37° and 31.5°.
Back in 2010, Sony led the mirrorless response to MFT, which was to target the prosumer stills sector, with the E mount the foundation for a lens lineup built around the APS-C sensor size. It was only in 2013 that the a7 appeared with a full frame (FF) sensor. Was the E mount ever designed for FF? It's difficult to know, but it is now one of the least competitive mounts at this sensor size, although, with an APS-C sensor, it has a 40° incidence angle. Whether this makes a difference to Sony's fortunes in the short- or long-term remains to be seen. Nikon stuck with the F mount to its detriment, while Canon iterated over the years, making its lens offerings compelling. Of course, it's important to remember that the trade-off for having a large throat diameter is bigger, heavier, and potentially more expensive lenses. A recent interview with Nikon by phototrend highlighted the demand for pancake lenses, which is perhaps something that Nikon is more easily able to leverage: a genuinely svelte lens lineup would make for a fine street camera.
Nikon Medium Format?
Which brings us back to Nikon's large Z mount and speculation about the potential to squeeze a medium format (44 mm by 33 mm) sensor underneath it. In the video below, photographer Matt Irwin outlines the possibility for Nikon to produce an MF Z-mount, where he uses scaled drawings to show what APS-C, FF, and medium format look like inside the Nikon, including a comparison with the Sony E-mount. What's interesting is the similarity in fit for a FF in Sony and MF in Nikon.
As Irwin points out, Nikon is certainly releasing some big, sharp glass at the moment. Has Nikon produced a mount with in-built developmental potential for MF? Crucially, do existing lenses produce an image circle that could cover an MF sensor? Is MF a development that is simply waiting in the wings for release?
The potential to have one lens for APS-C, FF, and MF will certainly have many salivating at the idea. However, it's worth looking at the two most recent mirrorless MF offerings: the Fuji G-mount (65 mm and 26.7 mm with a 31° incidence angle) and Hasselblad XCD-mount (61 mm and 18.14 mm with a 38° incidence angle). The throat diameters are much bigger than any FF mount, although not dramatically so compared to the Nikon Z. If Nikon were to build for MF, it would give an incidence angle of 34.5°, remarkably still better than the Fuji G, but in a smaller package.
It's interesting we have tended not to see manufacturers upscale their mounts to bigger sensors, Sony being the notable exception. It usually works in the opposite direction by putting APS-C sensors inside FF cameras. However, with the cost of sensors reducing and the requirement for camera manufacturers to significantly differentiate themselves from smartphones, is MF the next frontier? I think the short answer is no for one simple reason: market segmentation.
MF cameras are relatively uncommon beasts in the film world and even more so in the digital world, simply because they are more expensive to buy and operate. The bodies and (especially) lenses are bigger, making them costly to manufacture and, coupled with lower sales, push the retail prices higher. That's not to say there isn't a market for them. There is, because the image quality can be sublime, while there are further benefits of shallow depth of field and a better resolution/low light trade-off. However, there are diminishing returns to the investment, and only the top end of the market can sustain them.
Manufacturers have long focused their systems around APS-C and FF as meeting the needs of the market and allowing them to develop lens ranges around them. It's an accepted ideology. Or is it? While Nikon, Canon, and Pentax may have followed this thinking, Olympus and Panasonic have gone MFT, while Fuji was firmly wedded to APS-C before adding MF to its lineup. Is conventional thinking about to be shaken up again? With silicon's cost plummeting and capabilities improving, is FF no longer the holy grail of the pro photographer? Is Fuji's APS-C/MF strategy the right one? Yet, we also see Panasonic adding FF to its MFT offering, and Olympus pushing its high-end OM-D E-M1X. Just as the early 2010s demonstrated, manufacturers don't know what consumers want, yet they are faced with a smartphone onslaught in the face of plummeting sales.
What we don't see in all of this is one mount servicing three sensor sizes. Will we see a bold strategic move from Nikon that will eclipse the other manufacturers? With no "1 system" to divert its attention and an F mount to slowly roll to retirement, it can fully focus its energies on one mount and one future. What will it be?
Footnote: It's worth noting that there is some misuse of throat diameter across a number of websites. The external diameter is from the outside of the mount, the internal diameter is from the inside of the mount, and the throat diameter then excludes any mount lugs. While the throat diameter is preferable, I've stuck to the internal diameter, as its more widely available.
Body image courtesy of Jürgen Matern via Wikipedia, used under Creative Commons.