Post by kiev4a on Feb 22, 2007 22:42:41 GMT -5
Think this falls as much under lenses as it does digital-- Anyway, since I got my D100 I have been using a 35-70mm AF Nikkor on it. The lens is compact --not much bigger than a normal, and very sharp for being an "entry level" lens. The 35-70 was basically an early "kit lens."
The other day I shot some photos outdoor on a bright sunny day and when I prococessed them they all seemed overexposed although not to the point where they couldn't be adjusted. That's a little strange because all Nikon DSLRs tend to underexpose about 1/3 stop. I shot some other photos in the early evening and inside the house with the flash and they were exposed properly. None of the camera settings were wrong so I just passed the problem off as my imagination.
Today I shot some more photos outside under a bright overcast and varied the exposures by as much as two stops on the low side. When I pulled the photos up on the computer all were overexposed by about the same amount.
Later in the day I was worrying about whether something was wrong with the camera when a little light suddenly went on in my head. I put a different lens on the camera and shot some outdoor stuff--all of which was right on the money exposure-wise. I got the 35-70 and held it so I could see the aperture blades, opened the aperture all the way and let go of the lever so it could snap back down to f16 when the lens was set. But the blades didn't "snap" back. The closer they got to f16 the slower they closed--sort of gliding.
So, outdoor pictures were getting overexposed because the aperture wasn't closing fast enough. It worked OK in low light because the aperture only had to close part way and the real slowdown doesn't seen to begin until the blades are about 1/3 of the way closed. Can't see any oil on the blades but something is making them bind slightly. Unfortunately the lens isn't worth enough to see about getting it repaired. Of note: The first 35-70 lens I got didn't work properly and I had to return it to the seller. Now this one has problems. Guess this isn't a good lens to buy used.
I thought the investigation of my mystery might be of interest to someone. This is the first time I've ever encountered a sluggish auto diaphragm.
The other day I shot some photos outdoor on a bright sunny day and when I prococessed them they all seemed overexposed although not to the point where they couldn't be adjusted. That's a little strange because all Nikon DSLRs tend to underexpose about 1/3 stop. I shot some other photos in the early evening and inside the house with the flash and they were exposed properly. None of the camera settings were wrong so I just passed the problem off as my imagination.
Today I shot some more photos outside under a bright overcast and varied the exposures by as much as two stops on the low side. When I pulled the photos up on the computer all were overexposed by about the same amount.
Later in the day I was worrying about whether something was wrong with the camera when a little light suddenly went on in my head. I put a different lens on the camera and shot some outdoor stuff--all of which was right on the money exposure-wise. I got the 35-70 and held it so I could see the aperture blades, opened the aperture all the way and let go of the lever so it could snap back down to f16 when the lens was set. But the blades didn't "snap" back. The closer they got to f16 the slower they closed--sort of gliding.
So, outdoor pictures were getting overexposed because the aperture wasn't closing fast enough. It worked OK in low light because the aperture only had to close part way and the real slowdown doesn't seen to begin until the blades are about 1/3 of the way closed. Can't see any oil on the blades but something is making them bind slightly. Unfortunately the lens isn't worth enough to see about getting it repaired. Of note: The first 35-70 lens I got didn't work properly and I had to return it to the seller. Now this one has problems. Guess this isn't a good lens to buy used.
I thought the investigation of my mystery might be of interest to someone. This is the first time I've ever encountered a sluggish auto diaphragm.