Quick answer
The Canon EF 50mm f/1.8 STM is not natively compatible with the Nikon D850. You can use it with a mechanical adapter, but you will lose autofocus and electronic aperture control.
Why native compatibility doesn't exist
Canon and Nikon use different lens mounts: Canon EF (and EF-S) lenses have a 54mm flange focal distance and electronic contacts that communicate with Canon bodies. The Nikon F-mount on the D850 has a 46.5mm flange distance and a different contact layout. Physically and electronically, they are not interchangeable without an adapter.
What an adapter can and cannot do
A simple mechanical adapter (without glass elements) can mount the Canon EF 50mm f/1.8 STM onto the Nikon D850. Because the flange distance of the Nikon mount is shorter, the adapter spaces the lens correctly for infinity focus. However, the D850 cannot control the Canon lens's aperture electronically, and the STM motor relies on Canon-specific communication. Expect to shoot wide open at f/1.8 only, and focus manually.
Lens compatibility FAQ
Can I mount a Canon EF 50mm f/1.8 STM on a Nikon D850?
Yes, with a mechanical adapter that has no glass elements. The adapter fills the flange distance difference and allows the lens to physically attach.
Will autofocus work?
No. The D850 cannot communicate with the Canon STM motor. You must focus manually using the lens's focus ring. Manual focus on a 45.7MP sensor requires careful technique; use magnified live view for precision.
Can I change the aperture?
No. Without electronic communication, the lens stays at its widest aperture (f/1.8). You cannot stop down to f/2.8, f/4, or smaller. Shooting only at f/1.8 limits depth of field control and may not be ideal for landscape or macro work.
Will image quality be affected?
Potentially. The D850's high-resolution sensor may reveal softness or aberrations that are less visible on lower-resolution bodies. Also, without electronic correction profiles, distortion and vignetting won't be automatically corrected. Test the combo before relying on it for critical work. Native Nikon F-mount lenses generally produce sharper, more predictable results.
Is there a better alternative?
For a similar field of view and speed on the D850, consider a native Nikon 50mm f/1.8G or f/1.4G lens. They offer full autofocus, aperture control, and electronic communication. Native lenses cost more upfront but save frustration and deliver consistent performance.
Products mentioned
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Canon EF 50mm f/1.8 STM: The Canon EF 50mm f/1.8 STM has a bright f/1.8 maximum aperture and uses Canon's STM stepping motor for smooth autofocus. On a Nikon D850 via adapter, you lose that autofocus motor and aperture control, so you must focus manually and shoot at f/1.8 only.
Canon EF 50mm f/1.8 STM
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Nikon D850 DSLR Camera (Body Only): The Nikon D850 is a 45.7MP full-frame DSLR with the Nikon F-mount and a wide array of native lenses. Its high resolution demands sharp glass; using an adapted lens without electronic correction may reveal optical flaws more readily than on a lower-resolution body.
Nikon D850 DSLR Camera (Body Only)
