NIKON 180MM 2.8 ED AI-S LENS not metering correctly in Aperture mode.

I am new to using the older manual focus lenses. I recently bought this 180mm lens. It takes beautiful photos but will not meter correctly on my D7100 or D700 in aperture mode (where my 135mm Ai lens does). At f2.8 the photo is underexposed with exposure increasing as the f stop number increases to the point where at F8 photos are drastically overexposed. At the moment I get around this by working in manual mode and reviewing the photos each time to get the exposure right but I didn't think I would have to do this with an Ai-S lens. I thought is was supposed to meter correctly in aperture mode on the D7100 and D700. What might be causing this to happen? Is there an easy fix?

I am assuming you program non - cpu f/2.8 - 180mm. Also refer to pigs 213,270,277,302,and 310. Although the AIS lenses I have are 28mm,43-86mm and 300mm f/4 I have not had trouble metering but I am usually in M-mode.

Exposure Time: 1/60 sec
F-Number: f/8.0
Exposure Program: Manual
ISO Speed Rating: 1250
Lens Aperture: f/8.0
Exposure Bias: 0 EV
Metering Mode: Spot This with 300mm AIS on a tripod. Available light at our Computer Club Meeting.

Lou CIoccio

Hi Lou, as far as I can tell, I have correctly programmed the D700 and D7100 for this lens. I followed the same steps as I did for the 135mm I own and it works fine. I also tried the lens on a D300 with the same problem result. Somehow this lens is not allowing proper metering on cameras when in aperture mode. When I get the exposure correct in M-mode it produces beautiful photos. I may have to return it to the seller if it won't work in Aperture mode which I believe it is supposed to do. Lou, I am grateful for your reply but am unsure of which reference the pages in your reply refer to.

It could very well be that the aperture blades are a little tight (sticking). When this happens, the blades don't have time to close for when exposure happens. Remove the lens and play with the little aperture lever to see if they open and close very freely when you change the aperture on the lens.
Are you also using the aperture ring to change your aperture? With my manual lenses (without CPU), I have to use the actual ring to change exposure.

Another point is that these manual lenses only work with matrix metering...

Good luck.

I wasn't quite sure but it seems you did every thing correctly. The pages I refer to was how the non cpu is set up but you already knew that. Now I wonder what the difference in AI (refer to AI D) and AIS; the two lenses that I used way back in film days and still have is the 28/3.5 and 43-86/3.5. Those worked fine with the D7K; I was very pleased. Marcel is correct on manual changing the aperture ring and the other thing he brings up is sticky blades as a possibility. If they are sticking it would give false readings.

Lou Cioccio

Think AIS had a milled out indentation for matrix but it was a long time ago

Thank you to everybody for your help. I have tried everything without success. It seems to work alright until placed on a camera. It won't meter correctly at all on a D7100, D700 and D300. The seller told me he last used it in 2000. I will have to return it which is a pity because when the exposure is correct it takes beautiful photos.

downunder said:

I have summed up the problem in the below message I sent to the seller asking to return the lens :"I have found that it does not meter correctly in any mode - and it should do on the D7100, D700 and D300 cameras that I have tried. It is a faulty lens. For some reason, it won't allow cameras to meter correctly. To give you an idea of the dramatic change in shutter spead readings on the camera screen when viewed at the one scene and set on aperture mode - at f2.8 1/1250sec (underexposed); at f4 1/400sec (just right); at f5.6 1/80sec; at f8 1/20sec resulting in massive overexposure at F8. When I get the exposure correct it takes beautiful photos. However, the only way I get the exposure correct is to place cameras in A mode. I then check the shutter speed at F4 which appears to be where the exposure is correct in A mode, and then use a factor of 1/2 the shutter speed for each stop down from F4 eg. in the case above f5.6 1/200sec (or double for F2.8). I then have to switch the mode to manual, set my calculated shutter speed for the aperture I am using, and take the photo but that is a slow way to take a photo, even for a manual focusing lens."

Click to expand...

Have you checked the depth of field to confirm that the aperture blades DO close to the desired aperture? If you could take a pic at 2.8 and another at f8, even if you have to cheat the shutter speed to get the correct exposure, the DOF would confirm if it's the aperture not working OK.

It was concluded in another forum that it is a non-functioning aperture problem that results in a one stop aperture change giving a two stop shutter change. The most likely suggested causes were a bent stop-down lever, a weak spring causing the aperture to stop down slower than it should, or oil or grease on the aperture blades causing it to stop down slower than it should. I don't think the seller intentionally sold me a faulty lens. He didn't even know that this lens could be used on modern digital cameras and last used the lens in 2000. I think he simply didn't test the lens before putting it up for sale, possibly because he no longer has a camera to test it on.

I finished up taking the lens to a Nikon Service Centre (600 kilometer round trip). The lens was irrepairable, something about the little lever at the back of the lens being stuck and loose ball bearings within the camera. The seller was very good and immediately repaid my money and left the lens with me. It makes a good paper weight but what a shame to see a fine lens end up like this.

I cannot speak for the D7100 but no programming is necessary with the D700. I practically never, due in great measure to just laziness on my part) bother to program the lens into the non-CPU menu and never have problems with exposure.

What this sounds a lot more to me is oil on the diaphragm blades, which can cause them to stick, often open.

What I find strange is that the lens was only with the technician from the Nikon Service Centre for a couple of minutes and the receptionist reported that the technician had said something about ball bearings coming loose and falling out. That to me would mean he accessed the internal workings of the lens and specifically the internal diaphragm mechanism within the lens in about 2 minutes. I am sure experts can do things fast but that seemed very fast to me. I just undid the 5 screws at the back of the lens and that took me a few minutes. I found that the little spring that connects the aperture lever to the lens was stretched to the point where it had no strength to move the aperture lever. My understanding is that when a photo is taken on a closed down aperture setting on the lens that the aperture first opens fully wide and then shuts down to the set aperture when taking the photo as the spring pulls back the aperture lever to close it down. I found that I could move the ring the aperture lever is on and freely open the aperture fully and then close it down to the set aperture manually with my hand with no resistance at all. The bad state of this little spring makes me believe that it has something to do with the aperture on this lens failing to stop down to the set aperture from fully open as the last step in taking the photo. This is what was happening with this lens - it was only partially stopping back down when a photo was taken leading to overexposure. Am I being cynical about the explanation provided by the technician? Maybe it is a sticky diaphragm that caused the spring to lose its strength and maybe technicians have ways of getting to a aperture mechanism very quickly but it would take someone with more expertese that me to tell if that is the case.