Modern Nikkor lenses: 60mm F2.8 Micro Nikkor with manual aperture ring (left) and 18-200mm F3.5 – 5.6 VR zoom. Notice the absence of the aperture ring on the zoom. Image made with Nikon D2Xs and 200 mm F4.0 Micro Nikkor and flash.
With today’s electronic technology-driven cameras, many of our exposure controls are as convenient as a finger push on the camera body. And with experience, we never have to remove our eye from the viewfinder.
The shutter speed and aperture selection is controlled electronically through the selector wheel on the camera body. However, in natural science photography there are cases where electronic aperture selection is not possible because the electronic connections between the lens and the camera body are not workable.
Do I mean the camera malfunctions? No, not at all. What I mean is that, through the addition of some components between the camera body and lens, the electronic circuitry is interrupted. This happens with some extension tubes and bellows (below), as well as microscope adapters. This is not uncommon, nor does it really pose a problem when you are aware of what’s really happening.
So without electronic aperture selection, apertures need to be selected manually with the aperture selector ring and the exposures made in Aperture Priority (or Av) shooting mode. The camera will measure the light that falls on the internal metering sensor and set the shutter speed appropriately.
There may be one problem, however. Some lenses do not have a manual aperture selection ring on the lens barrel. Nikon calls these lenses “G” lenses. We fondly call them “gelded” lenses. Many Canon lenses are without the ring as well. So, it ends up that these are not really appropriate for this type of photography. We need to look for those lenses with aperture rings available. There a number of current Nikkor optics with the aperture ring. The 60 mm, 105 mm, and 200 mm macro lenses still have the aperture selector ring. Also the series of manual Nikkor lenses from 20 mm to 105 mm also retain the aperture selector ring.
Fortunately, under the correct circumstances, many older lenses (Canon and Nikon, too) may be used on modern D-SLR cameras. These lenses frequently have the aperture selector ring. And with adapters, Nikkor lenses may be used on Canon EOS series camera bodies. This is a nice option due to the great selection available of Nikkor optics.