On most Nikon cameras, exposure is locked using the AE-L button. I’m not familiar with the D200, so I can’t say where exactly this might be located. Sometimes (usually?) it’s combined with the focus lock button (AF-L), and a menu selection can enable one, the other, or both to be locked when the button is pushed.

However, as Neil says, this is moot when in manual mode. FULL manual mode, that is. There are photographers who are using manual mode to lock shutter speed and aperture, and using AUTO-ISO to match sensor speed to the exposure, rather than the other way around, so even that assumption has to be somewhat tempered.

Warmest regards,
- Arved

Lydia, your exposure settings are by definition ‘locked’ when you use manual exposure mode, since YOU set the aperture, shutter speed and ISO. They aren’t going anywhere until YOU spin the dials.

Neil vN

and, lower down:

“Therefore I had to control my exposure – in this case by locking a relevant meter reading in manual mode.”

Please explain how and where to lock the meter reading in manual mode for spot metering. Nikon D200

Thanks a stack