focusing problem?

[Blob]

My D50 seems to be working fine except I noticed it can't focus on a solid color image like a wall. The wall of my study is dark green and the camera can not autofocus on to it. Nor will it focus on a sheet of white paper unless I am setting a custom white balance, using the PRE function. Is this normal?

I have tried AF-A, AF-S and AF-C and the results are the same. I had to set the camera and body to manual focus to shoot a white screen on my computer--cleaning dust off my sensor cover.

I am using a nikon G lens.

Thanks,

Bob

[coldrain]

Cameras need contrast to focus, they need to see difference in focussed or not focussed. A wall without structure does not offer much contrast for the camera te determine when is the best focus.

I do not know what lens you are using, but the choice of lens does have something to do with the cameras AF performance. A wider aperture lens lets in more light, giving more contrast chance to the AF sensors.
Also, the sharper a lens is, the better the camera can focus, since then fine structures show up for the AF sensor.

So, yes, it is normal what you are seeing. And some lenses let the camera focus easier than others due to detail and light.

[K1W1]

Try an experiment. Put something contrasting on the wall maybe a decent sized piece of bluetack that won't damage the surface and see if the focus works.