D7000 – peculiar feature

[mongo]

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 !!!

[knumbnutz]

Partial LCD viewfinder ?
LCD takes very little battery to work except when you backlight it. Maybe that ?

[Lance B]

Partial LCD viewfinder ?
LCD takes very little battery to work except when you backlight it. Maybe that ?

No, I am sure it hasn't got a partial LCD VF.

The only thing I can think of is that it might have something to do with lighting up the ground glass screen is some way so as to assist in focusing?

[mongo]

Just discovered Mongo's D200 does exactly the same thing. Would not be surprised if all digital SLRs did the same also. Interesting.

[arthurking83]

Almost certainly something to do with LCD/powered assistance in the vf. Stuff like grid lines, focus points and so on.
That is, if the grid lines are overlaid onto the vf screen via an LCD screen, this LCD screen will need to be powered up to be viewable(and hence for the viewer to see the grid lines. When the batery power is removed, the grid lines become invisible, indicating a reverse polarity in the LCD(LCD's work the same way as a polariser does).
If the LCD is polarised one way so that the grid lines are viewable(say with battery power on), then it makes sense that the LCD is then reversed when power is removed and grid lines are now invisible. The LCD will become darker.
Grid lines and AF points use an LCD overlay.

Dunno how it works exactly, but you will notice how the crop lines also disappear with the battery removed.
D70s does this, so Mongo's hypothesis may be correct(in that all DSLR's do this). I thought they all did anyhow, ever since the D70s days.

[Lance B]

Almost certainly something to do with LCD/powered assistance in the vf. Stuff like grid lines, focus points and so on.
That is, if the grid lines are overlaid onto the vf screen via an LCD screen, this LCD screen will need to be powered up to be viewable(and hence for the viewer to see the grid lines. When the batery power is removed, the grid lines become invisible, indicating a reverse polarity in the LCD(LCD's work the same way as a polariser does).
If the LCD is polarised one way so that the grid lines are viewable(say with battery power on), then it makes sense that the LCD is then reversed when power is removed and grid lines are now invisible. The LCD will become darker.
Grid lines and AF points use an LCD overlay.

Dunno how it works exactly, but you will notice how the crop lines also disappear with the battery removed.
D70s does this, so Mongo's hypothesis may be correct(in that all DSLR's do this). I thought they all did anyhow, ever since the D70s days.

No, not all DSLR's do this. My Pentax's had their own grid lines on the plastci focus screen, which was great as this means that you could use aftermarket ground glass focus screens with your own grid lines (or none if you so wish) on the focus screen. I used the Katz Eye ground glass screens and they were fantastic.

I still cannot see why the focus would be off when there is no battery as it doesn't really make sense as the focus screen should still allow you to focus accurately. I know that the grid lines are powered up by the battery, as it does this with my D700 as well, but for the focus to be out of whack when the battery is removed is strange. I can only hypothesise that the battery also powers up something to do with the focus screen like maybe affecting the ground glass screen's appearance, or just that it makes it more difficult to see in order to focus and therefore you can't focus accurately.

[JM Tran]

that is interesting indeed. I have not noticed this with Pentax and Canon cameras.

[N*A*M]

i have noticed it with my Nikon DSLRs. it's just part of the way the screens work and arthur is probably on the money. not really an issue because even if you could see and focus, you can't take any pictures without a battery. i wonder if the pentamirror bodies are the same.

[Blueywa]

All mine work with battery removed, Body AF/M switch in M mode.

[Sar NOP]

Just discovered Mongo's D200 does exactly the same thing. Would not be surprised if all digital SLRs did the same also. Interesting.

Not with all DSLR, mongo : my D2Hs and D2X don't do that. Their viewfinders stay bright when the battery is removed.