There have been many breathless articles in the technology press lately about how the Sony A7r IV is the “best camera for this or that purpose”, due primarily to its resolution – often without really looking at anything else about it. While I have not personally used an A7r IV yet, reports from actual users are almost uniformly positive – there is no doubt that it is an exceptionally capable camera, one that will not constrain essentially any photographer’s creativity. Its resolution, however, is not the primary reason to choose an A7r IV (or any of its equally capable competitors).
The difference in sensor resolution among modern high-resolution cameras is unimportant in almost every case. The Sony A7r IV may be the best choice for you – or it might be the Nikon Z7 or D850, the Panasonic S1r, the Leica SL2 or a medium-format Fujifilm GFX. The only camera whose resolution really exceeds that of a modern 40+ MP sensor is the Fujifilm GFX 100 (not including Phase One and Hasselblad backs that are several times the price of the $10,000 GFX) – and the GFX’s resolution only matters in special cases involving very large prints or significant cropping. Any of the 40+ MP cameras offer significantly higher resolution than a 24 MP body, which matters if you are printing 20×30” or larger (or 16×24” with very close-up viewing conditions).
The real differences among this group of cameras don’t come down to an easily expressed number like resolution. Each does some things better than the pack, and each matches some styles of photography better than others. If you photograph a lot of moving subjects, Sony’s eye-tracking AF is significantly ahead of the pack (and Panasonic’s lack of phase-detection AF is a negative feature). Nikon’s unique low ISOs offer an utterly noiseless file if you have the light or the camera support to use them, and there is a special look to those files. Leica has an unusual microlens arrangement that improves quality with their classic M and R lenses. Panasonic and Leica have a tripod-only ultra-high resolution pixel shift mode that competes with a $50,000 Phase One IQ4 150. Finally, Fujifilm and Hasselblad offer medium format where the competition is full frame – there’s a slightly different look to the larger format (even excluding the GFX 100 and its significantly higher resolution).
Realistically, most of us will choose among these cameras based on our existing lens collections and what system we are used to. If you’re choosing without regard to a large investment of money or learning in one system or another, the features in the previous paragraph matter much more than a slight difference in resolution. Even more important is how the camera feels in your hand, and how well you get along with its controls. A camera is a tool you interact with in a very direct and personal way, and some of us will fit better with one than another. Do you like a space-age Sony or a very traditional Fujifilm GFX 50R that might be mistaken for a film camera until you notice the rear screen? Does a Nikon whose dials have been in much the same place since the F5 in 1996 resonate with your muscle memory? Do you like a bigger camera like a Panasonic, a Leica, a Nikon D850 or a medium-format Fujifilm, or do you prefer a smaller Sony or Nikon Z7? If you love Apple products with (at most) the minimum possible number of buttons, maybe you’ll love the Leica SL2. If you want everything to be on a physical button, dial or switch, how about a GFX 50R or a Panasonic S1r?
A Panasonic S1r showing many of its controls – many features are shared with the Leica above, but they’re accessed in different ways.
The use of a higher resolution camera is essentially to make a larger print, or a print with more detail. At a constant resolution, the A7r IV will make a print 1.15x as large in each dimension as a Nikon Z7 or D850 and 1.14x as large as a Panasonic S1r or a Leica S2. It will print 1.09x as large as a Canon 5Ds or 5DsR, and less than 1.2x as large as its own predecessor the A7r III. On average, the “next print size up” is between 1.33x and nearly 2x as large – even with closely spaced print sizes, the resolution does not buy a full print size at equivalent detail from any modern high resolution camera. A full print size is roughly the jump from 24 MP to the ~45 MP class cameras. The jump from a 36 MP camera like the original A7r to the 60 MP A7r IV is almost a full print size – and that’s one of the most appealing A7r IV upgrade scenarios.
Looking at it another way, the Sony offers 264 dpi on a 24×36” print, the Nikons 229 dpi, the Panasonic and Leica 232 dpi, the Canon 241 dpi, and the A7r III 220. These are all very similar numbers, and any competent printer software can rescale any of them to 300 or 360 dpi for the printer at extremely high quality. It will be very hard, if not impossible, to tell the difference. If you aren’t making prints of at least 20×30” , any one of these cameras will significantly exceed 300 dpi at 18×24” – the printer will be throwing away data from all of them…
Yet another approach is to look at what film format would have been required to make the prints we are making from digital files. It’s tricky, because film, development and scanning technology vary so much. Tech Pan exposed at ISO 6 and developed in Microdol is going to give a very different effective resolution at the same film size from Tri-X pushed to ISO 1600 – the same is true between, say, Velvia 50 or Ektar 25 and Kodacolor Gold 800. Taking a relatively
average film scanned on a high-end flatbed scanner, the 40+ MP cameras have pushed well past any standard medium format film, and are approaching the quality of 4×5” film.
Each of these cameras will exceed what any rational computer display is capable of. Even the $5000 (plus $1000 for the stand) Apple XDR display can’t display any of these cameras’ files at 100% – as a matter of fact, it can’t quite display a full file from a 24MP camera. A 4K monitor, TV or projector is only around 8 MP, and most social media sites use images at around 1-2 MP. The very few 8K displays in existence will just about display an image from a ~45 MP camera horizontally at 100%, but will crop the top and bottom of the image significantly.
The A7r IV is in a class of cameras that offer enough resolution for exceptional 24×36” prints even viewed very close, but it is not alone in that class, and its extra resolution is at most a marginal advantage. Any of these cameras will print beautifully even well in excess of 24×36”, both because of good resizing algorithms and because really large prints tend not to be mounted a foot from the viewer’s nose. Even for a 40×60” or larger print, there wouldn’t be a major difference between the A7r IV and other cameras in its rarefied class. If the subject is amenable to the size, weight and somewhat slower autofocus of a GFX 100, it offers 1.22x the resolution of the A7r IV, and 1.46x the resolution of an A7r III – 1.46x is clearly visible with careful examination. The GFX 100 offers a one full print size advantage over most members of the high-resolution full frame class (and something similar over its own 50 MP stablemates), and a partial print size even over the A7r IV.
If the resolution isn’t the reason to choose among the high-resolution cameras, then what is? First of all, before seriously considering any of these cameras, do you have access to a 24” or larger printer and regularly print at that size? If not, the whole group of 40+ MP cameras don’t really outperform 24 MP cameras with a comparable lens. It takes a 20×30” or 24×36”
print to really see the quality difference between really good 24 MP APS-C with a great lens and ~45 MP full-frame with a great lens. You can see it under very close inspection on a 16×24” print, but almost certainly not on the wall, and almost certainly not on any smaller print. If you are printing in the range of 20×30” and larger, there are fully modern choices from Sony, Nikon, Fujifilm, Panasonic and Leica all capable of very high quality (plus older models from Canon and Pentax). If you are printing up to 16×24”, add the Sigma fp, plus 24 MP full frame models from all of the manufacturers of high-resolution cameras except Fujifilm, plus Fujifilm’s APS-C lineup with its excellent lenses. Maybe add 24 MP APS-C DSLRs and other mirrorless cameras – the sensors are clearly up to a 16×24” print, but many of the APS-C specific lenses are not.
If you are going to print big, and want the image quality the high-resolution cameras can provide, what is a rational way to choose among the various >40 MP options? Resolution barely matters (except in the case of the GFX 100, which has a notably higher resolution that could be important on a 40×60” or larger print). Most importantly, if you have valuable Sony, Nikon or L-mount full-frame lenses, there is a very strong incentive to stick with your system unless you are moving for reasons having nothing to do with image quality. The Nikon FTZ adapter is pretty much flawless – Nikon DSLR lenses work exceptionally well on the Z system , and should almost be counted as native lenses. The exception is lenses for which a Z-mount equivalent exists, since most of the Z lenses are significant improvements over equivalent DSLR lenses. The very compact 24-70 f4 Z lens is actually as sharp as any version of the much larger 24-70 f2.8 DSLR lens (and the much larger 24-70 f2.8 Z is supposedly by far the best standard zoom Nikon has ever made). The 50mm f1.8 Z is a far superior lens to any 50mm SLR Nikkor, at least comparable to recent top-end ~50mm lenses like the Sigma ART, and gives up shockingly little even to the mighty 55mm Zeiss Otus.
Looking at lens lineups, Sony and Nikon have a significant lead over L-mount and GFX. Sony certainly has the largest selection of dedicated mirrorless lenses, including multiple options where no other manufacturer has more than one. One extreme example is standard primes – Nikon has two options (one of which is the exotic manual focus $8000 Noct), L-mount has 6 (two Leicas over $4000, one Panasonic for $2300 and three Sigmas). Sony makes four of their own lenses from $250 to $1500 (two are Sony/ Zeiss collaborations), plus three Sigmas and a Zeiss. In all cases, there are additional manual focus options, and there are inexpensive AF lenses from Samyang and Rokinon for Sony as well. Unlike any other full-frame mirrorless mount, Sony offers a complete lens lineup from ultra-wide to super telephoto without the use of adapters. About the only important missing lens is a 300mm f2.8 – anything else that’s missing is highly exotic (tilt-shift lenses, circular fisheyes, beyond 600mm).
Nikon competes in a different way here – they have a relatively complete dedicated Z- mount lens lineup below 100mm, focusing on extremely sharp, relatively compact lenses with modest apertures, with a huge hole in the telephotos. This hole is filled by the FTZ adapter , which allows 60 years of Nikon F-mount lenses to function as native lenses. Including F-mount Nikkors on the FTZ, Nikon’s lens lineup easily exceeds even Sony’s, including the exotics – Nikon has made everything from a 6mm fisheye that sees behind itself to a 1200-1700mm zoom and a 2000mm mirror lens over the years. Canon has equally stable adapters and a comparable optical zoo, but they don’t have the bodies to compete with Sony and Nikon right now.
There is a special situation if you have either M-mount or R-mount Leica lenses. The best adapter for those is to L-mount bodies – Leica makes excellent first-party versions. The new Leica SL2 has a special microlens design that purports to offer higher image quality with Leica lenses that weren’t originally made with digital cameras in mind. The SL2 is expensive, but quite possibly worth it for owners of valuable Leica lens collections.
There is much less incentive to preserve lens compatibility if your lenses are APS-C (or, in the case of Panasonic, even Micro 4/3). There are very few APS-C lenses that are worth using in crop mode on a high-resolution full-frame camera – and many of the exceptions are Fujifilm lenses that are not compatible with any full-frame body. The incentive to stick with your system if you are moving from a crop-frame camera is that all of these cameras behave a lot like other bodies from the same manufacturer. If you’ve been using a D7200, a Z7 will feel a lot more familiar than an A7r MKIV – and, conversely, if you’re coming from an a6000, the A7r mk IV will be the familiar choice. Gear other than lenses tends to be compatible across a single brand, so any investment in Sony, Nikon or L-mount compatible flash and many other accessories will be compatible with the same manufacturer’s high-resolution camera. Leica and Panasonic flashes are compatible within brands, but not with each other – Leica uses the same flashes as the rangefinder M, medium format S and APS-C TL lines, while Panasonic flashes are compatible with Micro 4/3
There are a couple of cases where existing lenses don’t matter as much. One is for Canon shooters who have gotten tired of waiting for Canon to release a high-resolution body other than the elderly 5Ds. If you have Canon lenses, there are basically three options other than buying a midrange EOS-R body. One is to keep waiting for Canon – their adapters should make excellent use of existing EF mount lenses on an EF-R body, and the new R-mount lenses are lovely, just waiting for a body. The second is to move to Sony, using third-party adapters to mount Canon lenses (by far the best adapters are for Sony bodies). These adapters are not as foolproof as Canon-to-Canon or Nikon-to-Nikon. The third option is to move to a system of your choice, giving up your Canon lenses.
The second situation is if you’re moving from a system where existing lens compatibility matters less, or if you don’t like your existing system for some reason. If your lenses are Pentax, you may not see a new body you want – or the bodies for your system could disappear entirely. If you have glorious old Hasselblad V-mount lenses, you might very well want to consider Hasselblad’s CFV II 50C back on a classic Hasselblad body, perhaps along with the 907X “sliver” body to use modern autofocus lenses – but one of the modern high-resolution cameras is another option.
In either of these cases, or if you have an existing system, there are more important things than resolution. Maybe an A7r IV is the best camera for you. The superb autofocus, battery life and improved ergonomics certainly make a case for it. But perhaps you like the best features of Nikon, Fujifilm, Panasonic or Leica instead. A gaudy resolution number should not stop anyone from considering any of those systems as well – no matter what tech publications looking to reduce everything to a single number say.