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Non-CPU Lens Data     Back to Nikon D300 Menu Hierarchy
by Makoto Honda     February 19, 2008   

When using a non-CPU lens, you can input the lens data to the camera (focal length & maximum aperture). Doing so will enable color matrix metering, improve the metering accuracy of center-weighted and spot-metering, as well as iTTL flash accuracy. Also, the aperture information displays in the viewfinder/panel. Without this manual setting, pictures taken by a non-CPU Ai lens tend to be under-exposed by as much as EV 0.7. (I do not understand why this much discrepancy when D300 is supposed to be AI-enabled.)

To set the non-CPU lens data, the following two steps are needed:

1) Preset the data of your non-CPU lenses prior to use.

You can enter lens data for up to 9 non-CPU lenses. This is done quite easily in the SETUP MENU.


Non-CPU lens data Hit OK after setting the following three items for each non-CPU lens you intent to use.
Lens number Set the lens number (to be recalled later) in the range of 1 - 9.
Focal length (mm) Set the focal length of the non-CPU lens.
Maximum aperture Set the maximum aperture of the non-CPU lens.

2) Select the lens number of a non-CPU lens you are using.

Hold the camera "button" and turn the main command dial until the lens number you want appears on the camera-top display. This will set the lens data to your camera. Each time you use your non-CPU lens, you just have to make sure to select the corresponding lens.

Now, which "button" to use depends on which button you had assigned to Choose non-CPU lens number function. You can set any of the three programmable buttons for this purpose: FUNC button, Preview button or AE-L/AF-L button. Select the button first (f4, f5 or f6 below) and for Button+Dial function, select Choose non-CPU lens number as below. I use FUNC button on the camera front for this purpose. 


f  Controls

f4   Assign FUNC button Default is Auto bracketing for dial (no setting for press only). Click here for detail.
f5   Assign preview button Default is Preview (no setting for dials). Click here for detail.
f6   Assign AE-L/AF-L button Default is AE-L/AF-L (lock both AE & AF). Click here for detail.

Button+Dial - When pressed in combination with a command dial:

1 step speed/aperture ---- Shutter speed (for S or M exposure mode) or Aperture (for A or M exposure mode) can be changed in 1 EV increment.
Choose non-CPU lens number ---- Choose a pre-registered non-CPU lens number. Click here for detail.
Auto bracketing ---- Main command dial to set the number of shots; sub-command dial to set bracketing increment.
Dynamic AF area ---- Main or sub-command dial to select 9 points, 21 points, 51 points or 51 points [3D-tracking]. Dynamic area AF & continuous AF mode only.
None ---- No function assigned.



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