Why does my Nikon D70s show a changing aperture with a macro prime in A or M mode?
Asked 1/9/2015
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2 answers
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On a Nikon D70s, the displayed aperture changes when focusing a prime macro lens in Aperture Priority or Manual mode. I’ve tested this with Nikon macro primes (around 60/65mm and 105mm), so it is not related to zooming. Is this normal behavior, or could the camera or lens be faulty?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
11y ago
2 Answers
4
The Nikon 60mm and 105mm lenses are macro lenses. As you focus closer than a certain point, the aperture decreases. For normal distances, both lenses should remain at 2.8, but as you get close to macro distance, you'll lose "effective" aperture.
There's a mathematical equation to calculate the loss of light and some more information here:
Originally by user25990. Source · Licensed CC BY-SA 4.0
user25990
11y ago
0
Generated from our catalog & community — verify before relying on it.
This is normal for macro lenses and usually not a fault.
With a macro lens, as you focus much closer, the lens extends internally/optically and the effective f-number increases. So even though the lens is nominally, for example, f/2.8, the camera may display a smaller maximum aperture at close focus. In other words, you lose light at high magnification.
At more normal focusing distances, the lens should stay at its stated maximum aperture, but near macro distances the effective aperture changes. This is a known behavior of macro optics and is separate from the variable-aperture behavior seen on some zoom lenses.
So if the aperture reading changes only as you focus very close, your D70s and lenses are most likely working as expected.
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