Cameras
Will it mount, and what will it actually do?
Which of your lenses keep autofocus on a new body, what a focal length really does on your sensor size, and which card will sustain the video mode you shoot.
Start with one of these questions
“I own lenses from my old camera. Will they fit the mirrorless body, and will autofocus still work?”
Which lenses physically mount, which keep autofocus and aperture control through an adapter, and why adapting works in one direction and not the other. Including the exceptions manufacturers publish themselves.
Check your lenses“Is a 35mm lens wide on my crop sensor? And is f/1.8 on crop 'really' f/2.7?”
How to translate a focal length and an f-number between full frame, APS-C and Micro Four Thirds — separating what changes framing, what changes depth of field, and what changes exposure. They are not the same answer.
Translate between formats“The manual says V60, the box says 'up to 280MB/s'. Which card do I actually buy?”
A card box carries up to four speed systems plus a bus type, and only some of them are promises about sustained writing. How to read them against the bitrate your own camera's manual states.
Decode the card markings
Five things the spec sheet buries
Each of these comes from a manufacturer's own manual, specification sheet or compatibility document — where the exceptions are actually written down.
- Nikon publishes the exception count itself: the FTZ II adapter mounts approximately 360 F-mount lenses, but only 94 of them — the AF-S, AF-P and AF-I types with a motor inside the lens — keep full autofocus and autoexposure. Older screw-drive AF-D lenses mount and meter but focus manually, because neither FTZ contains a drive motor. Observed, Nikon UK FTZ II page, accessed 2026-09-22.
- Adapting works in one direction because of flange focal distance — the gap between the lens mount and the sensor. Nikon states its Z mount has a 55 mm inner diameter and a 16 mm flange focal distance; the F mount it replaced sits much further out. An adapter is a spacer, so a DSLR lens can move onto a mirrorless body and still reach infinity focus, while the reverse leaves no room. Flange figure observed, Nikon USA Z-mount page; the one-directional consequence is inferred from that figure. Accessed 2026-09-22.
- "Full frame" is not one number. Canon's EOS R5 manual states full-frame shooting captures approximately 36.0 x 24.0 mm; Sony's a7 IV specification states 35.9 mm x 23.9 mm; Fujifilm's X-T5 states 23.5 mm x 15.7 mm; OM System's OM-1 Mark II states 17.3 x 13.0 mm. Crop factor is the ratio of those diagonals, not a brand label. All four observed from manufacturer specification pages, accessed 2026-09-22.
- Mount a crop-format lens on a full-frame Canon body and the camera decides for you. Canon's EOS R5 manual: "RF-S and EF-S lenses capture a 3:2 area in the center at an approx. 1.6 crop factor (APS-C size)", and "Areas outside the cropped area are not recorded in RAW shooting." The cropped pixels are gone, not recoverable later. Observed, Canon EOS R5 product manual, accessed 2026-09-22.
- An SD card carries up to four different speed systems plus a bus type, and only some of them are promises. Speed Class (C2/C4/C6/C10), UHS Speed Class (U1/U3) and Video Speed Class (V6/V10/V30/V60/V90) are minimum sustained write speeds in MB/s — 30 MB/s for both U3 and V30, 90 MB/s for V90. The large "up to" number on the front of the package is a maximum read figure, not a guarantee. Minimums observed from SanDisk's support article; the four-system structure observed from the SD Association. Accessed 2026-09-22.
Who this is for
People who have already picked a camera system and are now stuck on one concrete spec or fit question before they spend money: which of my existing lenses will physically mount and still autofocus on this body, what focal length do I need on this sensor size, and which memory card will actually sustain the video mode I shoot. It is not for someone asking which camera is best.