Calibrate individual AF sensors?

[Frode]

A bit dissapointed, but in a way accepted mine D4s to be not so good regarding AF in dim tungsten light (indoors). Also thought my AF- S 400 2.8 VR would perform better at f/2.8....always using crossensors.

Then, by an coincidence, i discovered that my outer AF sensors (AF- S and single Point) gave me tack sharp images at f/1.4 with my AF- S 50 1.4. When I tried ANY of the 15 crossensors, they where consistent in front focusing.

Thinking of sending it in for calibration. But before I do that; any thoughts/experiences?

[Erik Lund]

Then I would use the AF fine tune to correct the 50mm for the inner focus fields and try again to see how much the outer focus points are,,,

[Bjørn Rørslett]

If the lens has chromatic aberrations, the spectral composition of the ambient light can be instrumental for focusing. That alone can explain the difference in behaviour between the 50 and 400 mm lens. Factor in field curvature and focus shift when stopping down,  and the matter becomes downright scary.

[stenrasmussen]

I'd say this is typical of the pre-D500/D5 AF sensors. Certain types of artificial light conditions make the camera confused wrt. AF. I would not keep my hopes high in terms of getting the outer AF sensors "pulled back" in order to getting aligned with the central cross ones. The AF sensor has 3 lenses above the AF sensor itself and as one unit can only (as far as I know) be adjusted by three screws to control pitch and roll of the sensor itself. Erik's suggestion is about as far as you can go. Bjørn is absolutely right, aberrations will bewilder the sensors, esp. the linear ones. It is one of the things one has to learn to live with. As with many things in life, a workaround for specific situations can be found.

[David H. Hartman]

Frode,

I would do AF fine tuning with the center focus point and expose the test photos at f/2.0 and hope for the best. Bjørn's last sentence is what I thought of and yes, scary.

Dave Hartman who claims less competence here than those who post above me.

I'm sure I'm in the same boat with my D800

[Frode]

Then I would use the AF fine tune to correct the 50mm for the inner focus fields and try again to see how much the outer focus points are,,,

Thanks Erik!

I did that and the inner focus points did require about +10....

[Frode]

If the lens has chromatic aberrations, the spectral composition of the ambient light can be instrumental for focusing. That alone can explain the difference in behaviour between the 50 and 400 mm lens. Factor in field curvature and focus shift when stopping down,  and the matter becomes downright scary.

Thanks Bjørn!

The 400 behaved the same in late afternoon (lighting) football match as the 50 in tungsten light indoors. When using the inner points, that is.

[Frode]

I'd say this is typical of the pre-D500/D5 AF sensors. Certain types of artificial light conditions make the camera confused wrt. AF. I would not keep my hopes high in terms of getting the outer AF sensors "pulled back" in order to getting aligned with the central cross ones. The AF sensor has 3 lenses above the AF sensor itself and as one unit can only (as far as I know) be adjusted by three screws to control pitch and roll of the sensor itself. Erik's suggestion is about as far as you can go. Bjørn is absolutely right, aberrations will bewilder the sensors, esp. the linear ones. It is one of the things one has to learn to live with. As with many things in life, a workaround for specific situations can be found.

Thanks Sten!

I,ve only used the 400 with the inner points, but I'm sure it's capable of sharper images at 2.8 than it produces now. I think it's the inner points that needs adjustment....

I'll talk to Arnt Ove and hear what he's got to say 🙂.

[stenrasmussen]

Thanks Sten!

I,ve only used the 400 with the inner points, but I'm sure it's capable of sharper images at 2.8 than it produces now. I think it's the inner points that needs adjustment....

I'll talk to Arnt Ove and hear what he's got to say 🙂.

Do that!

[Erik Lund]

I would think they/Nikon adjust all of the focus points in one round,,, and they use a 50mm

[Frode]

Frode,

I would do AF fine tuning with the center focus point and expose the test photos at f/2.0 and hope for the best. Bjørn's last sentence is what I thought of and yes, scary.

Dave Hartman who claims less competence here than those who post above me.

I'm sure I'm in the same boat with my D800

Thanks David!

It looks like it's normal behaviour among these cameraes. Got to borrow a D4 from my local store and this camera behaves the same way.

The sollution looks like some AF- tuning.

Might as well work on my long lens technique also in order to get sharp images at f/2.8......🙂.

[Frode]

Contacted Fotocare (Vegard) and I was told that the "workaround" was to fine tune when using mine combination  (D4s and AF-S 50 1.4) in tungsten lighting.  Another sollution was that  the lens characteristics  itself might be the reason....

Closer examination showed that it was only the 50mm which needed fine tuning in tungsten lighting (only crossensors needed finetuning). The 400 was just fine 😊.

[stenrasmussen]

I've shot the D3S, Df and the D500 i parallell at stage shows with horrible mix of light sources this weekend. The D500's AF system seem almost impossible to fault...it really is that good. So I am convinced Nikon's made a huge step forward from the D4 series as well. One dreaded lens on the Df is the Sigma 35/1.4A. Focusing in artificial light is a hit and miss. Not so with the D500...

[Frode]

I've shot the D3S, Df and the D500 i parallell at stage shows with horrible mix of light sources this weekend. The D500's AF system seem almost impossible to fault...it really is that good. So I am convinced Nikon's made a huge step forward from the D4 series as well. One dreaded lens on the Df is the Sigma 35/1.4A. Focusing in artificial light is a hit and miss. Not so with the D500...

Sten, I`m not listening, you hear.......can`t afford a D5 these days....

The Sigma sounds like my AF- S 50 1.4....

Several people I trust also tells me that the AF of the D500 is great, even compared to D4/D4s. The high iso performance is rather so so am I told (it`s good up til iso 1600). Of course YMMV.

[MFloyd]

I used a D4s (not a D4) for almost two years until I replaced it with a D5.  Never, but never I got AF problems with the D4s. And I'm working in quite challenging AF conditions (action/sport).