I'd never noticed this before

ChrisR · Post by **ChrisR** » Tue Oct 20, 2009 5:12 am

Peering through the viewfinder (D700, right angled attachment, screwed on, with eyecup) at something dark, which might require a couple of seconds at iso 200, the lighting always looks a bit uneven, with a slight hot-spot in the middle. I thought it was the effect of some small reflections in the pentaprism. It's not there on the "Live View", which of course is processed to be lighter or whatever.

I'm reviewing my focus-creep problem today, and the camera happens to have no battery in it. The image is darker, and evenly lit. I can barely see to focus. With a battery in, with the camera turned on or off, it's brighter.
No light is going down via the eyecup.
With the lens end of extension tubes sealed around my eye, viewfinder shut, all I can see is a slight red glow while the viewfinder grid is illuminated, otherwise I can't tell if the battery is in or not (though I can feel a draught while I slide it in!).

So if no light is going down to the subject, the image is being affected electrically, somehow, presumably in the pentaprism. I didn't know they did that.

Do they all do it?

DaveW · Post by **DaveW** » Tue Oct 20, 2009 7:13 am

Hi Chris,

It is a known fact with Nikon DSLR's that even to manual focus using the screen you must have a battery in and the camera MUST be switched on.

I made that mistake when I first got my D200 since I tried to adjust the dioptric compensation on the viewfinder before I first put the battery in. I could not get the screen really sharp as with my old fully manual F2. I at first thought the dioptric adjustment must be electronic and required battery power to move it, but I believe it is simply that today's focusing screens are now overlaid with LCD displays for such things as auto focus indicators etc which do not clear properly unless they are receiving some charge from the battery'

Also, unlike my old F2, you do not adjust the dioptric focus by using an actual subject on the focusing screen, but should use the centre autofocusing brackets that are overlaid on the screen for setting it. With the battery in and camera switched on you adjust the viewfinder dioptric adjustment so the centre autofocus brackets are at their sharpest, then the focusing screen is automatically in focus.

It is there in the handbook telling you to insert the battery, switch on etc then set dioptric adjustment, but does not tell you why. If you switch the camera off, put it to your eye and then switch on you will notice the screen gets lighter.

I don't know if it applies to other modern DSLR's as well?

DaveW

ChrisR · Post by **ChrisR** » Tue Oct 20, 2009 7:20 am

If you switch the camera off, put it to your eye and then switch on you will notice the screen gets lighter.

No, that's not it!! It doesn't do that.
That's why I underlined it!
Whether the camera is switched on or not makes no difference, it's whether the battery is IN or not! Battery in, it's lighter.

I'm not referring to focus, except that it's darker and harder to see the image without the battery .

NikonUser · Post by **NikonUser** » Tue Oct 20, 2009 7:46 am

On my D90 it makes no difference to brightness whether card is in or not; no difference with camera off or on and any permutation.

DaveW · Post by **DaveW** » Tue Oct 20, 2009 8:14 am

Evidently it is not the on or off switch then, but whether battery is connected or not. The Nikon's do use some battery power even if switched off since you will notice that the number of images left on the memory card is still indicated whether the camera is switched on or not. Therefore this charge must also be going to the focusing screen too, whether the camera is on or off?

As I said before I too did not have the battery in at first when I noticed this effect. I did find a link some time ago that recorded it but cannot locate it again. As Chris says NU it is nothing to do with the card but whether battery power is available or not. Try taking the battery out and see. With an old fully manual SLR it would make no difference to screen clarity or brightness.

DaveW

ChrisR · Post by **ChrisR** » Tue Oct 20, 2009 9:43 am

it is not the on or off switch then, but whether battery is connected or not.

Yes, that's right, that's what I said..!

I tried an N80, which is several years old, but fairly modern in terms of Nikon's development, which also does it. An older F801s, which if course is AF etc, doesn't.

DaveW · Post by **DaveW** » Tue Oct 20, 2009 10:53 am

It was a while since I did it Chris so was just going from memory and thought it did it switched off as well, but I knew it occurred when no power was available.

Not only did I find the screen darkened but it was fuzzy too, and if I tried to focus on something I could not get it sharp. Not something I expected since I presumed the optics of the focusing screen would be independent of the power supply, though I did not expect the LCD focus brackets etc to light up.

However my manual did say insert the battery first and then adjust the dioptric correction as I detailed earlier. As I said it is a known effect, though have heard several reasons given for it, though Joseph Wisniewski explains it here on the last post of the link below:-

http://photo.net/nikon-camera-forum/006Yx4

This from a D50 review:-

"Interestingly, the focusing screen is dependent on power – when the battery is not in the camera, the display is dark, grainy, and uneven – and impossible to focus. Of course, without the battery, the camera is a paperweight anyway."

One purchaser of a secondhand Nikon on another site, which was sold stating the battery was dead and needing replacement, thought he had bought a dud camera in need of repair since it would not sharp focus, until he was told this occured without a charged battery. Once a new battery was installed he said the camera was perfect!

I believe it does it too on some of the later Nikon film cameras with similar focusing screen set-up's, not just DSLR's.

DaveW

ChrisR · Post by **ChrisR** » Wed Oct 21, 2009 2:09 am

DaveW wrote:I believe it does it too on some of the later Nikon film cameras with similar focusing screen set-up's, not just DSLR's.DaveW

I tried an N80, which is several years old, but fairly modern in terms of Nikon's development, which also does it.

DaveW · Post by **DaveW** » Wed Oct 21, 2009 2:54 am

A chap on another site I am on, who is a salesman at Jessops, the UK camera stores, says they always put a battery in before handing a demonstration camera over to a customer so they don't get the remark that "the viewfinders dark, you can't see properly through it!"

As you can see from my earlier link written in 2003, even Canon and Olympus had cameras with similar focusing screen overlays, and since then no doubt many more cameras show the same fuzzy darkened viewfinder without battery power.

DaveW