non cpu metering issue?

[2WheelPhoto]

Hi, I have an old lens I'm playing with. Its an AF 28-70mm Nikkor. My D7000 either hates it or I'm doing something wrong, which is probabably the case. Its set up in my cam's dbase as max f-stop 3.5 and focal length 70mm. I have it loaded onto a function button.

Some pics come out with the light WAY off. For example, I walked out back focused and shot two quick pics the same into nothing and one is blown out of the park. I'm sure I can tweak it right in manual mode and raise shutter speed, but i want the cam to work with it. Cam in aperture priority, and one pic at F/20 and one at F/5.

Any suggestions or steps I'm missing? Maybe something I'm not doing or not doing right? I'm hoping its newB thing I'm overlooking entirely.

Thanks

ISO 100 38mm f20 aperture priority 1/25th

ISO 100 38mm f5 aperture priority 1/400th

 

[Derrel]

Re you sure it was at f/20 and not f/2.0? heh heh heh...it looks pretty blown-out. Is the lens diaphragm functioning well,and not lazy or sticky?

 

[2WheelPhoto]

Thanks, I guess it could be a lens problem, just weird as it consistantly works between f3.5 and f10. Its noticeable as the fstop decreases, and completely blown out at f18 and f20. I don't have another old AF lens to compare to or I'd have a better idea if I'm hosing it or if its my gear.

 

[KmH]

Thanks, I guess it could be a lens problem, just weird as it consistantly works between f3.5 and f10. Its noticeable as the fstop decreases, and completely blown out at f18 and f20. I don't have another old AF lens to compare to or I'd have a better idea if I'm hosing it or if its my gear.

That description is a clear indication there is a a likely aperture mechanism issue, and the aperture is not stopping all the way down to the smaller apertures.

 

[tirediron]

Take the lens off of the camera, set the aperture to it's minimum (smallest, ie f32) and manually operate the stop-down leaver with your finger while looking down the lens. Watch the diameter to ensure that it decreases in size smoothly and doesn't 'catch'. I agree, it does seem like an aperture issue.

 

[Derrel]

Wait a second....you wrote "AF 28-70mm Nikkor"....how exactly is that a NON-CPU lens, if it's an AF Nikkor? If it is an AF Nikkor lens with a CPU in it, you would not want to tell the camera it is a manual lens...so...is it actually an AF Nikkor 28-70, or is it a Ai-S, manual focusing lens?

 

[2WheelPhoto]

Derrel, if i don't program the cam as non-cpu this lens just shows "error".


I really appreciate the help. tirediron, I did just that and its smooth as can be from tiny hole to wide open as big as the glass. At its lowest it stays put wide open.

Also to check and see if my cam is metering correctly and hasn't died, i put my 35mm prime lens on to note the shutter speed for each fstop and took a few pics. worked great. put the old AF lens on, same shutter speed and priority, and its blown out.

I'm wondering if this thing deserves a proper burial. I just so wish i had another ancient AF to benchmark it against because I'm still at such a loss whether its something I have wrong or the lens. I went through the manual again and it mentions some non-cpu require centerweighted and spot metering, I made sure mine was set to center which is where I keep it most of the time and it was, and then I changed it to spot and took a few pics. Same thing, blown out.

 

[Josh66]

Have you tried metering wide open, then stopping down and adjusting your shutter speed by the same amount?

If that works, I would say that the meter just isn't accurate in low light (like when the lens is stopped down). Or, for some other reason, stopping down is causing some other issue with the meter.

 

[2WheelPhoto]

Have you tried metering wide open, then stopping down and adjusting your shutter speed by the same amount?

If that works, I would say that the meter just isn't accurate in low light (like when the lens is stopped down). Or, for some other reason, stopping down is causing some other issue with the meter.

I compared the metering with another lens in the same light and fstop and the shutter speed was almost exact. I'll try your suggestion too if i can figure it out. I"ll meter at 3.5 then stop it on down to f20 plus decrease shutter speed manually-

 

[Josh66]

Have you tried metering wide open, then stopping down and adjusting your shutter speed by the same amount?

If that works, I would say that the meter just isn't accurate in low light (like when the lens is stopped down). Or, for some other reason, stopping down is causing some other issue with the meter.

I compared the metering with another lens in the same light and fstop and the shutter speed was almost exact. I'll try your suggestion too if i can figure it out. I"ll meter at 3.5 then stop it on down to f20 plus decrease shutter speed manually-

Put the camera on manual. Set the lens wide open (or close - stopping it down to the first full stop makes the math easier to do in your head), the set the shutter speed to whatever it needs to be for that aperture. Stop the lens down to the desired aperture - keep track of how many stops you're changing it by. Change the shutter speed by the same number of stops, but in the opposite direction.

Example: If at f/4 your shutter speed is 1/2000, at f/16 the shutter speed should be 1/125. (That's a change of 4 stops. f/4 -> f/5.6 -> f/8 -> f/11 -> f/16 ... 1/2000 -> 1/1000 -> 1/500 -> 1/250 -> 1/125.) If you get a 'normal' looking picture by doing that, there is "something" up with your meter. Probably just not enough light getting in with the lens stopped down to get an accurate reading.

 

[2WheelPhoto]

Thanks, I shot the same pic at "f/4 @1/320" and it came out nice, then shot at "f/16 @ 40". Last pic is blown out.

Seems to be the aperture doesn't close when the cam is on the body? I did the manual test in the above post and lever is smooth and it opens and closes and feels so precise off the cam.

 

[Josh66]

Yes, if that didn't work, I would say that there is something wrong with the lens itself.

Can you manually manipulate the apreture lever with the lens off of the body? Does it function normally?

Sounds like maybe at some point, the aperture blades just stop moving...

 

[Derrel]

Sounds like the automatic diaphragm linkage is broken! I have never,ever heard of an AF Nikkor needing to be programmed as if it a non-CPU lens...

Can you put the lens on the camera, and look through the front of the lens, and see if it is actually stopping down to the mid- and smaller apertures??? My feeling is that the diaphragm is NOT stopping down when the camera is shooting exposures.

 

[2WheelPhoto]

Yes, if that didn't work, I would say that there is something wrong with the lens itself.

Can you manually manipulate the apreture lever with the lens off of the body? Does it function normally?

Sounds like maybe at some point, the aperture blades just stop moving...

Yes sir, did that per my above post when the gentleman suggested it and the little lever worked smooth as glass off cam and the blades opened wide to small. I liked that old timey AF lens on the cam, but maybe its time to give it a proper burial. I really appreciate the help from all of you, and learned a lot in the process.

 

[2WheelPhoto]

Sounds like the automatic diaphragm linkage is broken! I have never,ever heard of an AF Nikkor needing to be programmed as if it a non-CPU lens...

Can you put the lens on the camera, and look through the front of the lens, and see if it is actually stopping down to the mid- and smaller apertures??? My feeling is that the diaphragm is NOT stopping down when the camera is shooting exposures.

We were posting at the same time. Honestly I can't see the blades move when its on cam, I checked for that and thought maybe i just couldn't see well enough to notice.