How can I configure my Nikon D-90 with minimum shutter speed of 1/60th of a second and aperture of f1.4 and have it adjust the ISO and speed as needed? I currently have it working with 1/60th fixed speed, but then outdoor pictures are overexposed.

I want the f-stop to hold at f 1.4 and the speed to be fast enough that I don't get blurred pictures and adjust the ISO as needed with faster shutter speed if maximum ISO would over expose.

Is this possible on the Nikon D-90?


2 Answers 2


If I understand correctly, you want:

  • a fixed aperture value (in this case, f/1.4)
  • a variable shutter speed not to go below a given minimum (in this case, 1/60th of a second)
  • variable ISO in order to maintain said shutter speed.

You want aperture priority mode, configured to use a minimum shutter speed. According to the D90 manual on page 166:

In exposure modes P and A, sensitivity will only be adjusted if underexposure would result at the shutter speed selected for Minimum shutter speed. Slower shutter speeds will be used only if optimum exposure can not be achieved at the ISO sensitivity value selected for Maximum sensitivity.

The only cases in which the camera would drop below your minimum shutter speed is if the camera has already adjusted the ISO and still cannot obtain a correct exposure.


It sounds like you want Auto ISO. In your menus, you can turn it on and set a minimal shutter speed. It will bump the ISO to keep the exposure above that shutter speed.

  • \$\begingroup\$ I think that is what I've done, only the shutter speed is fixed not minimum, hence my question. \$\endgroup\$
    – WilliamKF
    Jun 11, 2011 at 0:37
  • \$\begingroup\$ @WilliamKF Are you in aperture mode then? \$\endgroup\$
    – rfusca
    Jun 11, 2011 at 0:49
  • 1
    \$\begingroup\$ In manual mode, it keeps aperture and shutter speed constant and varies ISO to maintain 'proper' exposure. In aperture mode, it holds aperture constant, and varies ISO to stay above the shutter minimal. \$\endgroup\$
    – rfusca
    Jun 11, 2011 at 0:51

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