Mongo was testing a D7000 yesterday with a manual lens. Crystal clear and sharp through the viewfinder.

The battery went flat. Pulled it out and put it on the charger.

In the interim, Mongo continued to play with the camera and lens for handling etc. Discovered that it is not possible to sharply focus even a manual lens without the battery inserted !!!!! Focus was close but very soft and a little cloudy.

Poped the semi-charged battery back in and – Presto ! the viewfinder gets a little brighter and it is possible to get razor sharp focus again ! EVEN WITH THE CAMERA STILL TURNED OFF!!!

Discussion: -

  1. One would have thought that in an SLR, there would just be a series of direct optical prisms connecting the viewfinder to the lens with no digital input. This does not appear to be correct based on what happened.
  2. Unless the physical presence of the battery in its chamber flips some sort of lever inside to change something (thus causing the viewfinder to operate normally), one might reasonably conclude that the battery is in use CONSTANTLY (even when the camera is OFF) to maintain the viewfinder function. The only way to test this theory is to place a completely dead battery in the chamber and see the results.
  3. THIS IS ALL VERY ODD !!!