Nikon D7200 autofocus doesn't work or works erratically in liveview

[ntz]

Hello,

I have a problem with my Tokina 70-200mm f/4 lens with Nikon D7200. In live view mode the autofocus doesn't work or works erratically, when using the viewfinder the autofocus seems working. It drives me nuts how this could happen ... few caveats:

1) I've tested other lenses, autofocus in live view mode seems working with them .. See please lenses in my signature, AF works with them in live view except for Tokina 70-200mm

2) I am using a back-button focus, but seems there is no difference if I switch back to camera standard settings

3) While in live view, all options in menu in "CUSTOM SETTINGS MENU" head "a Autofocus" are greyed out when the LiveView is on, for other lenses too so perhaps this ain't issue ..

4) In LiveView the autofocus is not completely dead, it tries to do something on AF-ON button, but it doesn't come to focus.

Questions:

What might cause that autofocus in LiveView doesn't work for specific lenses ? Is it problem with camera or problem with lens ? Some idea what to do with that ?

thank you in advance for any input ..

best regards, ~dan

 

[flyingPhoto]

what are you trying to auto focus on? not all lenses are exactly great at various subjects.

for example, i was laying under a fruite tree a few weeks ago with my d7500 and a nikon 75-300 lens, and it would NOT autofocus on the white blossoms against a super bright sky. had to manual focus
just couldnt pick anything out from the back ground. many lenses have that issue if there is not enough contrast between object and back ground.

 

[ntz]

what are you trying to auto focus on? not all lenses are exactly great at various subjects.

for example, i was laying under a fruite tree a few weeks ago with my d7500 and a nikon 75-300 lens, and it would NOT autofocus on the white blossoms against a super bright sky. had to manual focus
just couldnt pick anything out from the back ground. many lenses have that issue if there is not enough contrast between object and back ground.

Hello,

thank you for your input ... I tried multiple objects of course .. seems there is some general problem .. sometimes it seemed that autofocus in live worked when I was zooming for example on green grass under the good light and the focus point was close, but on distant objects the autofocus in general doesn't work at all (in all modes AF-F and AF-S) .. through viewfinder the autofocus works fine ..

I cannot tell if it worked before or not, I've hit this issue when I just wanted to "calibrate" my focus (found such a article), normally I shoot with these lens handheld and with viewfinder, so there focus works and if shooting from tripod I tend to use manual focus usually ..

I tried all focal lengths 70-140-200, I've tried the kit lens 18-140 and they AF in LiveView at 140mm on same object with no issue so that led me to conclusion that there is something wrong with these Tokina lens

 

[flyingPhoto]

Distortion performance top

The Tokina 70-200mm has typical barrel distortion at 70mm and pincushion at 200mm. It's about the same as other 70-200 lenses and the same as Nikon's 70-200/4 VR.

Plug these figures into Photoshop's lens distortion filter to correct it. These aren't facts or specifications, they are the results of my research that requires hours of photography and calculations on the resulting data.

​	FX at 3.3' (1m)​	FX at 10' (3m)​	FX at 33' (10m)​
70mm​	+1.0​	+2.8​	+3.0​
105mm​	-1.0​	0.0​	-0.5​
135mm​	-2.0​	-1.0​	-1.2​
200mm​	-3.0​	-2.5​	-2.0​

© 2014 KenRockwell.com. All rights reserved.

​

 

[flyingPhoto]

the thing with off brand lenses is that you are not garunteed perfect function on all cameras.

Considering the lens is rather new, and the camera is made after any known compatability issue date, SEND IT TO THE COMPANY THAT MADE IT.

Seems like something is truly wrong with it.

 

[RowdyRay]

I wanted to touch on the "compatibility" issue. Because it may be just that. Is the D7200 running the latest firmware?

When I got my used Canon 80d I updated the firmware and put it through it's paces to check it out. All was fine until.....I used live view with the Tamron 150-600mm G1. Locked the camera right up. Literally. Had to remove the battery. Tried the other 5 lenses I owned and worked fine. Shortly after another member asked about the same thing. I googled and found others had the same issue. Contacted Canon and Tamron. Got responses but no resolution. Yet.

Tried Googling your issue with no luck. Contact Nikon and Tokina. Ask if they've had similar complaints. Or, if if it could be a firmware/compatibility issue or defect.

 

[ntz]

Hello Rowdy ... Tokina is known to ignore the mailbox entirely and Nikon, okay, I can ask them .. Yes, I have the latest firmware .. I have already some plan .. I will go to the local store and "try" another 70-200mm lens to see, if another piece of same hardware does it .. if so, it will be clear ..

 

[smoke665]

have a problem with my Tokina 70-200mm f/4 lens with Nikon D7200. In live view mode the autofocus doesn't work or works erratically, when using the viewfinder the autofocus seems working.

Not surprising, that you're experiencing this. Your camera like many others uses Contrast Detection to focus when in live view, a slower system which bypasses the regular AF sensor and uses the image formed on the main sensor itself. In low light or scenes that lack contrast it will hunt because it cant find an edge.

The viewfinder uses a separate Phase Detect sensor with two sensors per AF point. It compares both and instructs the camera to adjust the focus till they match. It's not as suseptable to issues with low contrast or light.

 

[ntz]

Not surprising, that you're experiencing this. Your camera like many others uses Contrast Detection to focus when in live view, a slower system which bypasses the regular AF sensor and uses the image formed on the main sensor itself. In low light or scenes that lack contrast it will hunt because it cant find an edge.

The viewfinder uses a separate Phase Detect sensor with two sensors per AF point. It compares both and instructs the camera to adjust the focus till they match. It's not as suseptable to issues with low contrast or light.

Thank you Smoky for an input !!!

 

[RowdyRay]

Hello Rowdy ... Tokina is known to ignore the mailbox entirely and Nikon, okay, I can ask them .. Yes, I have the latest firmware .. I have already some plan .. I will go to the local store and "try" another 70-200mm lens to see, if another piece of same hardware does it .. if so, it will be clear ..

Ok, just checking. Sounds like a good idea. Curious what the result is.