Steve DeMott Loc: St. Louis, Missouri (Oakville area)

Camera is a Nikon D750 - About 16,000 shutter count
Sigma 24mm f/2.8 Lens - Lowest aperture camera will display f/2.8
Nikon 50mm f1.4 D - Lowest aperture camera will display f/1.4
Nikon 60mm Macro f/2.8 D - Lowest aperture camera will display f/3.2 ???
Nikon 105mm Macro f/2.8 D - Lowest aperture camera will display f/3.2 ???
Nikon 28-300mm f/3.5-5.6 G - Lowest aperture camera will display f/3.5
Nikon 70-300mm f/4.5-5.6 - Lowest aperture camera will display f/4.8 ???
All lens & camera bought from KEH 3-4 years ago.
All lenses will produce a correct exposure +/- 1/3 exposure from largest, middle to smallest aperture.
Usually I'm using the lenses at f/5.6-16.
I have cleaned the contacts, both camera and lens.
Preview button works on all lenses the same, aperture doesn't appear to be sticking or slow.

My concern is the macro lenses that won't stop down to f/2.8, as viewed through the camera viewfinder.
Is 1/3 stop something to worry about?

TIA
Steve

kymarto Loc: Portland OR and Milan Italy

No

sippyjug104 Loc: Missouri

Steve, the f-number of the lens is the ratio of the lens focal length to the diameter of the entrance pupil. Therefore, it is a physical attribute of the lens. At the maximum aperture, the blades of the iris should be fully retracted. If there the camera does not report the maximum value, it is more likely the way the camera is receiving the info from the lens and not the lens itself. When the lens is off the camera, and you hold it up to a light, and rotate the aperture setting you should be able to see if the iris fully retracts into the body of the lens.

Steve DeMott Loc: St. Louis, Missouri (Oakville area)

Thanks Sippy

The big question is why would that have changed. I have photos with the D750 that the exif claims f/2.8.
I'd send it to Nikon for a check-up, but another used lens probably would cost less.

The mysteries of life.
Steve

Strodav Loc: Houston, Tx

The lens is fine. I freaked the first time I noticed it and did a little research. You might want to read the following.

https://www.dslrbodies.com/lenses/macro-information/macro-lens-working-distance.html

Here's an excerpt: "Note that all Micro-Nikkors use a combination of focal length and focus extension to get to 1:1 (life-size) magnification ratios, which also impacts the maximum aperture value reported."