Stafford

Are the lens and battery from a Nikon D7100 compatible with the D850?

Steve Perry Loc: Sylvania, Ohio

Sort of.

The battery is technically compatible, although it won't have the same life as the newer (gray colored) battery will (has to do with the output behavior or something). As for the lens, it'll work, but if it's a DX lens the camera will only use the DX crop area of the sensor (19.4MP).

juan_uy Loc: Uruguay

Batteries looks as compatible, although the new EN-EL15a of the D850 would be better (https://www.dpreview.com/forums/thread/4200995#forum-post-60078247)

Lenses are compatible, although DX lenses will be cropped and not use the whole sensor of the D850.

Shellback Loc: North of Cheyenne Bottoms Wetlands - Kansas

Lens - You can use DX lenses with the FX format D750. If you use a DX lens, you will need to set the "Auto DX Crop" item of the "Image Area" menu to tell the camera to either remain in FX mode (and suffer severe vignetting of your images), or to automatically switch to DX mode whenever a DX lens is attached.


From the Nikon web site - https://imaging.nikon.com/lineup/dslr/index.htm

7100 Battery
EN-EL15 Rechargeable Li-ion Battery

750 Battery
EN-EL15 Rechargeable Li-ion Battery

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

There are a few DX lenses, like the 35mm F1.8 and the 10.5 Fisheye primes, and the Tokina 11-16 zoom if used at 16mm, that can work with an FX camera and cover the sensor.

https://photographylife.com/using-nikon-dx-lenses-on-fx-cameras

http://360virtualtourist.com/shaving-nikkor-10-5mm-fisheye-lens-hood/ (if you have the intestinal fortitude)

rgrenaderphoto Loc: Hollywood, CA

What Steve said about lenses is spot on. On batteries, I have never seen any appreciable difference in performance on the EL15 or 15a's, but I never let them go to full drain, and do not pay attention to how long they last.

CaryATL Loc: Atlanta, GA

Yes, the batteries are compatible. The 15a is supposed to perform better in cold weather as well as last slightly longer. I was looking to pick up another battery for my D7100 and discovered the 15a is now the only thing on offer as far as official Nikon. Also, the old 15 had a manufacturing lot that was recalled. My 15 battery was fine, but they fixed the manufacturing problem and issued the updated design as the 15a to avoid confusion. You can buy the 15a and it will work in your D7100 or a D850.

billnikon Loc: Pennsylvania/Ohio/Florida/Maui/Oregon/Vermont

Yes, the battery and lenses for the D7100 will work on the D850. The gray battery that comes with the D850 is designed to give you more running time than the battery you have on the D7100. You could keep the D7100 and use that battery as a back up to your gray one that comes with the D850.
Your lens will communicate itself to the D850 that it is a DX (cropped sensor) lens and you will get acceptable images with it, BUT, that lens will not take advantage of the image quality you can get from the D850. (sort of like putting a VW bug engine in a Bentley) You just don't get the performance you expected.
My advice, sell your current d7100 with lens (or lenses) or trade it in on the D850 and get a quality FX lens. I would further suggest the Nikon 35mm 1.8 as a starter lens, https://www.bhphotovideo.com/c/product/1023361-USA/nikon_2215_af_s_nikkor_35mm_f_1_8g.html.
Or, I really like my Nikon 24-120 f4 lens on the D850.
Couple of extra things to keep in mind, it is quite a step up from the D7100 to the D850, have you considered the D500, you current D7100 lens and battery will work just fine on it. That step may be easier to take than going to the D850.
And the D850 is still hard to get, they are becoming available but in limited numbers. Many camera stores have been waiting and waiting for their shipments of D850's. And most of the ones that are on order are already sold.
Another idea to keep in mind, the D500 will be discounted further in a few weeks on black friday and cyber monday. Nikon usually throws in the vertical grip for free and discounts the very fine 16-80 f2.8-4 lens for 1/2 price. And I believe your stepping up to the D500 would be a better move than moving up to the D850. Just my opinion.