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Several readers have written confused about the D850 operating range, confusing battery ratings with camera temperature operating range.
I can state (from direct use), that the D810 operates right down to 0°F using the EN-EL15 battery and that the D850 with its EN-EL15a battery operates down to at least as cold as 24°F—for extended periods e.g., star shots for 20 minutes or so. It is not to be taken seriously that the 'a' version behaves differently in any significant way.
When battery specs are quoted, they bear little relation to real world shooting. About the only important thing to know is to not charge lithium batteries that are below freezing. Some types will be destroyed if charged when sub-freezing (and some have circuitry or chargers to prevent that from happening by refusing charging current, another reason not to use off-brand chargers).
Discharging most types of lithium batteries down to 0°F is just fine , albeit with reduced voltage and usage time.
Ditto for my 5 kilowatt Lithionics battery in my Mercedes Sprinter photography adventure van, in which I now have experience down to 18°F outside, 23°F inside and internal battery temps to 34°F. Flawless operation.
Above and below, Nikon has done a slipshod confusing job that has tripped up several readers already. It should have been presented/written as follows in order to avoid confusing the long dash with a negative sign:
0°C to 40°C (32°F to 104°F)
The quality of nearly all user manuals for cameras and electronics devices gets an 'F' (failing grade), and not just for sloppy work like here with Nikon—see Why do User Manuals for High-End Cameras Tell Nothing Useful?.
I checked the Nikon D800 manual and it quotes the same operating range as the battery. In fact, *all* quoted operating environment / operating temperature specifications for the Nikon D850 match those of the battery. Or Canon DSLR: the Canon 5Ds user manual states an identical operating range.
Clearly the specifications are in error versus the real world (“cover our butts”) because a great deal of my usage of the D850 for several weeks now was well below the minimum operating temperature. It is my assumption that all these specifications relate back to the battery specifications, which as noted are simply not accurate in the real world and relate to ideal operating performance. I shoot in sub-freezing temps and have for many years with many cameras of many brands, and so have many other Nikon users.
If it were actually true that the D850 did not operate sub-freezing, I would say it is the biggest piece of crap yet sold in the camera market, and that would be overly kind. But it is not true, since that’s what I’ve been doing for weeks (shooting sub-freezing).
BTW, no Nikon should operate anywhere in the northeast USA, southeast asia, Florida, Death Valley, Australia, etc for many months of the year because those places all have humidity well above 85% for many months of the year. And temperature extremes too. I hope the picture is getting clear here.
Leica makes some interesting statements about the Leica M10 battery:
The battery must have a temperature of 10°-30°C /50°-86°F to be charged (otherwise the charger will not turn on, or will turn off again).
Pentax does a better job in the 645Z user manual, stating: “The temperature range for camera use is -10°C to 40°C (14°F to 104°F).”