I have a D600 and a modest collection of MF non-CPU (ai and ai-S) lenses. I can't for the life of me figure out how auto-ISO and the auto-shutter speed options work.
I have input the focal length and apertures of my lenses in the non-CPU lens bank, and my exposures are fine at fixed ISO values. However if I enable auto-ISO and the automatic minimum shutter speed, I seem to get only absurdly high shutter speeds and ISOs in aperture-priority mode.
For example, I have a 75-150 f/3.5 Series-E which is configured as a 105/3.5 (as a compromise) in the non-CPU lens bank. I tried both indoors and out, and I never got below ISO 1250, with a crazy 1/2000 shutter speed outside, or ISO 5000 with a 1/320th shutter inside. I tried all of the fast/slow options in the automatic shutter settings menu and it didn't seem to make any difference.
I feel that I understand how it is supposed to work, as with my 28-105 3.5-4.5D AF lens, everything works normally in Auto-ISO - i.e. the shutter is 1/focal length in the middle setting and faster or slower by 1-stop increments in either direction.
Hi Brian. Thanks for your reply. My first test was with the 75-150 3.5 and I tried it wide-open at f/3.5 and also at f/4.
I did some more testing last night, and I am beginning to think that the auto shutter-speed setting ignores the focal lengths input into the non-CPU lens list. Here is a comparison I did just before sunset last night with the camera in aperture-priority mode, matrix metering and auto-ISO with auto-shutter on the middle (default) setting.
With 28-105 AF-D lens set to f/8:
28mm - f/8 1/30 @ ISO 640 35mm - f/8 1/40 @ ISO 800 55mm - f/8 1/60 @ ISO 1400 105mm - f/8 1/125 @ ISO 3600
Now with the manual-focus non-cpu primes also set to f/8: 28mm f/2 Nikkor - f/8 1/30 @ ISO 800 55mm f/3.5 Micro Nikkor - f/8 1/30 @ ISO 1000 105mm f/2.5 Nikkor - f/8 1/30 @ ISO 800
As you can see, the auto-ISO, auto-shutter speed behaves as designed with the AF-D lens. However, it did not seem to care about the focal length of the non-CPU primes. I do not know why it stuck with 1/30s for all of the lenses.
According to the D600 manual, if you set the minimum shutter speed to AUTO in the Auto ISO sensitivity control menu, you'll always get a minimum shutter speed of 1/30th of a second with a non-CPU lens.
I suspect that's what you are running into.
"There is no real magic in photography, just the sloppy intersection of physics and art." — Kirk Tuck