AF NIKKOR 70-300 1.4-5.6 ED Acting Weird

[danny_o]

I bought this lens new. For years, it was an almost constant favourite, on my various cameras.

Maybe 5 years ago, this lens became erratic, unwilling to autofocus on my D200.

 

Naturally, I switched to manual focus, but I brought the lens in to L.L.Lozeau, in Montreal, and asked for recommendations: CLA, repair. or what.

 

The techie tried the lens on several cameras at the counter. and the lens focussed perfectly. I didn't have my D200 with me at that time, though.

 

I purchased another D200, used of course, and the lens will not autofocus on either of the Digital cameras.

 

I have several buddies with more recent (D 7100) cameras, and the lens will not autofocus on any of them.

 

Meanwhile, I have several other autofocus lenses for Nikon, and all perform perfectly on my D200 cameras.

 

Also, and most importantly, I use several Nikon film cameras with autofocus: F90x (2 of them), F65 and F4; on all film cameras, this autofocus lens operates and focusses beautifully, as do any of my other Nikkor or other lenses.

 

SO: I have a Nikkor autofocus lens that used to perform accurately on my digital camera ( and on various others), which no longer will focus automatically on any digital camera. NB, if I switch off the autofocus switch on the camera, the focus ring rotates freely, and focus is accurate.

 

Meanwhile, this same lens connects perfectly on any autofocus film camera that I have.

 

I've cleaned the contacts on all of my cameras ( film and digital), I've cleaned the contacts on the lens.

All other autofocus lenses operate as expected on all cameras.

 

At this point, I have been working around this silly problem, since I also use several manual lenses, but the ridiculous bugger still baffles me.

 

Any ideas?

[Mary Doo]

Hmm... intriguing. Looks like you tried everything and tested with various variables. But, just checking:

• Were you testing in low light or low ISO? Have you tried cranking up the ISO for the test?
  
• By any chance the back dial (round thing at the back of the camera) is in lock position?
  
• Both camera and lens are set to autofocus?
  
• Have you tried resetting the camera to factory defaults, and completely reboot the camera by removing the battery and putting it back?
  

[Andrew Garrard]

Just to make sure someone more knowledgeable is on the right page, this is the 70-300mm f/4-5.6D ED AF ZOOM-NIKKOR, not the newer 2016 AF-S VR f/4.5-5.6G version? I presume so, since the G lens would be a pain on the F4.

 

I'm sure someone more experienced with lens diagnostics can help, but just an out-of-the-box thought in case... I imagine the film bodies are relying solely on the current output from their AF sensors, whereas I wouldn't be surprised if the newer AF systems on the digital bodies were trying to make use of the distance information recorded by the lens to help with predictive AF. This may be gibberish, but... might the distance encoder in the lens be b0rked? Have you tried all AF modes to see if it makes a difference? Have you tried live view AF on the D7100 (which would bypass any phase detect questions)? Even in manual focus you should be able to see focus distance in the EXIF, which would tell you whether this is definitely, or just probably, a red herring.

 

I wouldn't expect there to be any mechanical difference in the AF capabilities between the bodies you tried, but have you attempted turning the lens's AF screw with a screwdriver, just in case it's tight and the F65 has a much stronger AF motor than I would expect it to? (The F5's one is scary and could double as a power drill, and would probably overpower a sticky lens, but I wouldn't expect your film bodies to be particularly stronger than the digitals'.)

 

Best of luck. I'm intrigued by this one; I've had AF stop working on lenses in the past, but it's never been body-specific.

[danny_o]

Just to make sure someone more knowledgeable is on the right page, this is the 70-300mm f/4-5.6D ED AF ZOOM-NIKKOR, not the newer 2016 AF-S VR f/4.5-5.6G version? I presume so, since the G lens would be a pain on the F4..

 

Andrew, yes that is the lens in question.

 

Your suggestion, that " the distance encoder in the lens (might) be b0rked? " seems to make sense. My understanding of the electronics involved lies somewhere between Zero and None-at-all, which is why I put the question out to the forum.

 

When I first bought the D200, that lens worked perfectly on it, but after a few years the performance became erratic, until it died completely. I was actually surprised to find that the lens works perfectly on the film cameras. That the D200 can fully use any of my other autofocus lenses only adds to the confusion.

 

As for the focus screw in the lens, yes, actually, that was something that I tried early on, and I've just tried it again at your suggestion. No problem with that, it rotates very easily, almost without tension.

 

Anyway, aside from being an intriguing curiosity, I've adapted to simply using the lens as a manual focus when using it on the digital cameras; strangely, and fortunately, the "Focus Indicator" in the viewfinder display works, and glows when the chosen focal point is in perfect focus.

 

Thanks for the suggestions, and I think you might be right about the "distance encoder".

[hjoseph7]

Look like somebody on Photo.Net had the same problem: Nikon AF 70-300mm 4-5.6G won't autofocus

[Andrew Garrard]

Look like somebody on Photo.Net had the same problem: Nikon AF 70-300mm 4-5.6G won't autofocus

 

Except, I believe, that lens doesn't autofocus at all. Refusing to autofocus on multiple dSLRs but working fine on multiple film bodies is... weird. Short of asking a Nikon service centre to have a look in the hope that they might not charge you for an interesting case, I suspect it might stay a mystery - I suspect engineering time overtakes the going rate for replacing this lens fairly quickly, although I've not checked.

 

Good luck, Danny. My guess was pretty obscure; I'm hoping someone here might come up with something more plausible, but if I'm right, I'll feel smug. :-) If you get the chance to try live view, I would be interested to know if that helps. That said, I notice the D850 manual (at least) says "use an AF-S or AF-P lens" for live view autofocus or you may not get "the desired results"; I hope that means the camera would still try to autofocus with a screwdriver lens, enough for a diagnostic, but I could be wrong, and haven't tried it.

[mike_halliwell]

I'm wondering whether it's a rotational wear issue resulting in pin misalignment?

 

The fact it used to be happy on your D200 and stopped points at something happening to either (or both) of those two (!)

 

Just checking...I'm guessing there wasn't Firmware update for the D200 that stopped it working with that lens? Not that that should cause intermittent then permanent failure.

 

I like the encoder thought!