Nikkor 50mm f/2 NAI lens darker on D50 and D60
I originally posted the below on DPReview, but maybe this is a better place...
I recently acquired an Nikkor 50mm f/2 NAI lens and mounted on both D50 and D60. It did not break either cameras.
The exposure is manual. But I noticed that the exposure is off by 1/3 stop at f/2 and only at f/2.
I made a series of exposures
1) f/4 1/30
2) f/2.8 1/60
3) f/2 1/125
All three exposures should be the same. But only #1 and #2 are the same. #3 looks too dark. To get the same exposure, I needed to use the following
4) f2 1/100 (+1/3 stop from #3)
Does anyone know the reason for this? Because
A) the lens is actually not f/2 but f/2.2 (-1/3 slower than f/2)
B) the lens is f/2, but because DSLR sensor works best with perpendicular rays, f/2 has many rays at large angles so it is 1/3 stop darker on the sensor
#1. "RE: Nikkor 50mm f/2 NAI lens darker on D50 and D60" | In response to Reply # 0Leonard62 Nikonian since 15th Mar 2009Fri 12-Jul-13 06:17 PM
I just checked two of my 50mm f2 lenses, I have four.
The first one is an original 5cm f2.0 S NAI lens. I shot 3 photos using my D3200 at the exact aperture/shutter speed settings you did. Even though it's mid afternoon it's a very cloudy day. The three photos looked perfectly exposed. No difference at all in the photos exposure except a very little darkening in the extreme corners due to vignetting at f2.0.
I then took my 50mm f2.0 HC which had been factory AI'd and put it on my D800 and set the correct lens data in the non-CPU entry in the setup menu. It had just started to mist and got a little darker outside so I focused on the white doors of my shed. I then adjusted the aperture in A mode and found that the shutter speeds tracked perfectly.
It showed f2/@1/1000, f2.8@1/500 and f4@1/250.
My lenses seem to be right on at f2.0. I don't know why yours isn't. You might want to make sure that your lens is opening fully when set to f2.
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