Hasselblad H4d Strange Focusing Issue

[leifhurst]

I can't tell if this is an issue with the lens or with the camera but here we go.

I've got a H4d-31 along with a 120mm Macro. I predominately use True Focus while shooting and it's never been an issue until today. About half way through a session with a client today, I notice the images are soft and out of focus. I remove and reattach the lens. Power cycle the camera and it's the same. I switch it over to manual focus and everything is fine. I finish out the session (albeit a little slower) and get him on his way. I put the camera on the work bench and I notice when True Focus is engaged on the camera and I lock focus, that while the shutter is firing during an exposure, the focusing meter jumps quite a bit. For instance if it's set to between 0,7 and 0,8 and I press the shutter button, the lens will creep over to 0,7 during the shutter actuation. I know True Focus operates by adjusting the focusing plane due to yaw movement but in my testing the camera is dead still from press True Focus to firing the shutter.

In Manual Focus, it does not move or change while firing.

Any ideas? 

[leifhurst]

Follow up question... is the True Focus system driven by potentiometers for axis positioning? Is it possible that one became stuck? Strangely, I gave the camera a little tap and everything is working now.

[Douglas Fairbank]

This may not answer your question but the true focus makes the correction just before the shutter fires, the lenses do not use potentiometers, the info is digital. Maybe you could clean the gold contacts with a soft cotton cloth or a cotton bud and a trace of alcohol.