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DPChallenge Forums >> Hardware and Software >> Autofocus problems ...
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03/30/2016 06:33:51 PM · #1
with 2 of my lenses. Untill yesterday I had no issues with my lenses, but today the autofocus of my Nikon 24-120mm lens didn't work. I cleaned the contacts of both the lens and the camera, but it still doesn't work. Focussing when using the live view of the camera (Nikon D800) did work well. Trying my other lenses I experienced the same problem with my Nikon 50mm (no autofocus, live view focussing worked well), but both my Nikon 70-210mm and Nikon 300mm worked fine.
Anyone has any idea about what's causing these problems and how to handle them?
03/30/2016 06:59:34 PM · #2
No clue, but my 28-70 started having intermittent autofocus issues as well :(
03/30/2016 08:13:05 PM · #3
It's the aliens. They don't like Nikons.
03/30/2016 08:16:19 PM · #4
Originally posted by Bear_Music:

It's the aliens. They don't like Nikons.


Ha!

Indeed.

I thought I responded to this... asking what you used to clean your contacts... (not the eye ones), but I don't see it.

Soooo...?
03/31/2016 02:22:40 AM · #5
I used the same fluid I use for cleaning my sensor (it's from DigiPads), I guess it's alcohol.

The strange thing is, when using my working lenses, looking through the viewfinder gives me a clear and bright view. But with the Nikon 24-120mm and the Nikon 50mm the view is far from bright, it's like I have a dark filter in place. And when focussing the motor drives the lens but no auto focus or exposure.
03/31/2016 06:52:48 AM · #6
Funny, but you're the second person I've heard complain about this issue in the 3 days, the other with a D750 and 14-24mm.

Questions:
- Is it not focusing at all through the viewfinder or just not locking focus?
- Is it consistent with both the shutter button and the AF-ON button?
- Does it not focus regardless of AF Mode?
- What is your Live View focus mode, AF-S (which should behave the same) or AF-F (which will try and focus regardless of whether a focus button is pressed)?
- Have you swapped lenses and had other lenses work normally?
03/31/2016 06:56:20 AM · #7
Originally posted by Kroburg:

I used the same fluid I use for cleaning my sensor (it's from DigiPads), I guess it's alcohol.

The strange thing is, when using my working lenses, looking through the viewfinder gives me a clear and bright view. But with the Nikon 24-120mm and the Nikon 50mm the view is far from bright, it's like I have a dark filter in place. And when focussing the motor drives the lens but no auto focus or exposure.


OK, so I saw this, so you can skip the last question. It sounds like something may be up with the aperture level where it's not opening all the way on those lenses, which may impact the camera's ability to achieve focus since it wants the lens wide open. If it's multiple lenses then it may be a camera issue. Can you slide the aperture lever on the lenses to get them wide open?
03/31/2016 08:30:18 AM · #8
Originally posted by JakeKurdsjuk:

Funny, but you're the second person I've heard complain about this issue in the 3 days, the other with a D750 and 14-24mm.

Questions:
- Is it not focusing at all through the viewfinder or just not locking focus?
- Is it consistent with both the shutter button and the AF-ON button?
- Does it not focus regardless of AF Mode?
- What is your Live View focus mode, AF-S (which should behave the same) or AF-F (which will try and focus regardless of whether a focus button is pressed)?
- Have you swapped lenses and had other lenses work normally?


When focussing the focus ring of the lens goes from closest position to infinite and back (or the other way around, depending on its original position). It's the same when using the shutter and the AF-ON button. Changing AF-modes doesn't change anything.
When focussing in Live View, it's in AF-S mode; I have to press the shutter/AF-ON button to focus. But is does focus. However, the exposure is way off. With sunny weather I only have 1/15 sec at f/4 on 100 ISO (on the Nikon 24-120), while my Nikon 70-210 shows 1/320 sec at f/4.5 on 100 ISO.

I can slide the aperture to wide open with that small lever on the lens mount and on the Nikon 50mm (the other affected lens) I can turn the aperture ring to wide open as well. But connected to the camera it seems the aperture is much smaller than shown in the viewfinder.
03/31/2016 08:54:28 AM · #9
It sure sounds like you have a communication problem that is resulting in a closed-down aperture on the affected lenses. Nikon lenses are "normally closed down," in other words, the aperture is at minimum size when the lens is powered down. I would expect that this is a "marginal contact" problem with the body, and that the lenses that work correctly manage to make contact, the others don't.
03/31/2016 09:07:47 AM · #10
Originally posted by kirbic:

It sure sounds like you have a communication problem that is resulting in a closed-down aperture on the affected lenses. Nikon lenses are "normally closed down," in other words, the aperture is at minimum size when the lens is powered down. I would expect that this is a "marginal contact" problem with the body, and that the lenses that work correctly manage to make contact, the others don't.

Seems logic. Only question: why did all lenses work well and then suddenly 2 of the 4 lenses stop working correctly? Must have anything to do with the contacts on the body, I guess.
03/31/2016 10:16:33 AM · #11
As Fritz points out, there's something with the aperture control going on with those lenses - the AF system is hunting because it cannot get enough light to determine focus (the Live View method is different, which is why you're OK).

Shine a light into the front of the lens - is the aperture closed or fully open (should be open)? What happens when you press the DoF Preview button when you change the aperture value? Does the aperture value change on the LCD when you turn the control wheel or is it fixed, and if fixed what does it say? When there's no lens on the camera there should be a lever in the center-left position of the lens mount as you look at it - is that lever in any way bent or damaged? When you mount the lens that lever should grab the aperture control on the lens and move it from fully closed to fully open. If it's slightly bent it could be grabbing some lenses and not others. If the apertures are not wide open after mounting the lens then that is what's going on.

Also, since the D800 has aperture preview in Live View try changing aperture settings with those lenses and see if anything happens. I would suspect not if my theory is correct.
03/31/2016 11:55:29 AM · #12
Originally posted by JakeKurdsjuk:

Also, since the D800 has aperture preview in Live View try changing aperture settings with those lenses and see if anything happens. I would suspect not if my theory is correct.

Wouldn't that be a "hypothesis"? (runs for shelter)
03/31/2016 12:13:51 PM · #13
Originally posted by JakeKurdsjuk:

As Fritz points out, there's something with the aperture control going on with those lenses - the AF system is hunting because it cannot get enough light to determine focus (the Live View method is different, which is why you're OK).

Shine a light into the front of the lens - is the aperture closed or fully open (should be open)? What happens when you press the DoF Preview button when you change the aperture value? Does the aperture value change on the LCD when you turn the control wheel or is it fixed, and if fixed what does it say? When there's no lens on the camera there should be a lever in the center-left position of the lens mount as you look at it - is that lever in any way bent or damaged? When you mount the lens that lever should grab the aperture control on the lens and move it from fully closed to fully open. If it's slightly bent it could be grabbing some lenses and not others. If the apertures are not wide open after mounting the lens then that is what's going on.

Also, since the D800 has aperture preview in Live View try changing aperture settings with those lenses and see if anything happens. I would suspect not if my theory is correct.


The aperture of the 2 lenses having problems are closed when on the body. Pressing the DoF button doesn't do anything; you can here the lever shift, but it has no effect on the aperture of the lens (seems logic, the aperture is already fully closed). I tested the 50mm lens by connecting it to the body with the aperture fully open: it is able to focus then, but not to expose. For exposure I have to turn the aperture ring back to f22, and then it can't focus anymore.
Changing aperture with the camera's control wheel does show on the LCD, also exposure changes, but again, it's not really connected with the aperture of the lens, because that one is closed even when the LCD shows f/4.

Talking about the lever on the lens mount, do you mean the one in the body, the small lever on the left that is connected with the DoF button? Or the small one on the top, that is pushed to the left when connecting a lens (i.e. with aperture ring, otherwise is doesn't shift at all)? Both levers seems fine, can't find any damage.
03/31/2016 01:06:29 PM · #14
Originally posted by Kroburg:

Talking about the lever on the lens mount, do you mean the one in the body, the small lever on the left that is connected with the DoF button? Or the small one on the top, that is pushed to the left when connecting a lens (i.e. with aperture ring, otherwise is doesn't shift at all)? Both levers seems fine, can't find any damage.


The one connected to the DoF Preview. It's what will grab the aperture tab on the lens and rotate it to the open position when the lens screws on. If the aperture is closed when mounted then the lever didn't make proper contact with the tab so it could push it open. When you press the DoF preview button in it releases the tab on the lens allowing it to close to the desired spot. I suspect that somehow the lever is missing the tab as the lens is mounted.
03/31/2016 01:08:51 PM · #15
Originally posted by Bear_Music:

Originally posted by JakeKurdsjuk:

Also, since the D800 has aperture preview in Live View try changing aperture settings with those lenses and see if anything happens. I would suspect not if my theory is correct.

Wouldn't that be a "hypothesis"? (runs for shelter)


I've tested the hypothesis on my end, I'm simply asking him to provide independent verification. ;)
03/31/2016 01:35:28 PM · #16
Your theory was right, Jake. Changing aperture in Live View didn't change exposure. I had a closer look at that lever and found it was placed slightly backwards. I used a small instrument to bring it forward again and now all my lenses are working again. I guess I need to be more careful now when changing lenses, that lever might have a weak spot now.

Thank you all for your help, I'm very pleased as you can understand.
03/31/2016 02:14:35 PM · #17
Originally posted by Kroburg:

Your theory was right, Jake. Changing aperture in Live View didn't change exposure. I had a closer look at that lever and found it was placed slightly backwards. I used a small instrument to bring it forward again and now all my lenses are working again. I guess I need to be more careful now when changing lenses, that lever might have a weak spot now.

Thank you all for your help, I'm very pleased as you can understand.


Sweet!! Glad I could be of help.

And see, Robert, I told you it was a theory!! LOL
03/31/2016 03:36:59 PM · #18
Brilliant! This has been classic DPC :-)
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