LiveView focus stuck on D750 and Tamron lens

[groz]

Hi,

I have a problem with liveview focussing on my Nikon D750 and Tamron SP 24-70mm f/2.8 DI VC USD Lens. The camera/lens will focus correctly until the first time it can’t focus (e.g. object too close, not enough light). From that point the camera refuses to even try to focus on anything in liveview mode. Switching the camera off and on again doesn’t help. The only thing that works is switching the camera off, detaching and reattaching the lens and switching it back on again. The issue is repeatable 100% of the time, every time the camera and lens first lose focus in liveview mode.

Can anyone suggest the cause of the problem and a permanent fix? I’ve previously owned the same equipment and had no such problems. I don't currently own another lens so can't confirm if the problem is with the camera or the lens.

 

[snowbear]

Does the same thing happen with the viewfinder (live view off)? Other lenses? Can you test the lens on another body?

 

[groz]

The problem never occurs with the viewfinder, only liveview. I've borrowed another Tamron lens and the liveview focus issue does not occur. I don't have another body I can test the lens against though.

It's weird. Liveview focussing works fine until the first time it's unable to get a focus (e.g. object too close). From that point, only detaching and reattaching the lens will resolve it.

 

[RVT1K]

Did you ever resolve the issue?

I'm afraid that I don't have any specific advice but the electronics tech in me says to start with taking the battery out.

I would then recommend using regular rubbing alcohol and Q-tips to clean any and all the contacts on the lens and on the camera body where the lens attaches. Pay careful attention to any contact that is spring loaded and make sure it is free to move.

 

[groz]

Hi RVT1K, thanks for your advice. I've tried cleaning the spring-loaded contacts on the lens with a Q-tip and optical cleaning fluid and it does seem much better. Previously, I could reproduce the issue 100% of the time. Now I struggle to get the issue to occur. I'm not going to say it's 100% fixed though until my wife's done a photo session with the baby and doesn't complain about the issue. I should find out tomorrow.

Separately, I've found a much less time consuming fix than detaching and reattaching the lens when the problem does occur. Simply going back to viewfinder and focusing on something there, then going back to liveview mode is enough to get focussing to work again in liveview mode.

Thanks again.

 

[RVT1K]

I'm glad things are much better even if you are not yet declaring victory.

Personally, I would not use anything on the electrical contacts other than IPA (rubbing alcohol) since it evaporates without leaving any residue. I've used almost exclusively for cleaning in my electronics career.

The electrical signals in your camera are actually quite small and it does not take much to interfere.