Nikon N8008 funny problem

David Lyga · Jul 10, 2020

If I do not fire this camera for maybe an hour or two (which is usually the case) the exposure is still made accurately but the mirror then stays up. To get the mirror back down, I simply press the shutter again. This second pressing pulls down the mirror and does NOT take another exposure or advance the film. In other words, 'no harm done'. If I then take more exposures (either immediately or within about one hour) everything is back to normal with the mirror.

The body looks brand new and there are no dried oil problems that would indicate a possible reason with older, mechanical bodies. This Nikon simply does not want to lower that mirror unless the previous exposure was 'recent'. I am convinced that this is a 'chip processing' problem, but everything else is perfect. - David Lyga

shutterfinger · Jul 10, 2020

Ignore the battery check indicator and install fresh name brand batteries.

David Lyga · Jul 10, 2020

Interesting. I never thought that this was a power problem. But, the next exposures, with the same batteries, are perfect.

shutterfinger · Jul 11, 2020

Vintage SLR's are all mechanical for the shutter/aperture/film advance operations via levers, gears, springs, and the user's finger power.
Introduce meters, now an electronic power source is required if the sensor does not generate power when exposed to light. This is low current draw.
Introduce auto film advance, vertical shutter travel, auto focus and the like requiring more power.
This is all solid state devices and motors. Solid state devices require a specific voltage range to operate in but are current dependent devices. The electronics of these cameras will only drop the voltage .05V to .1 volt when fully activated on fresh batteries. Marginal batteries that are at the low end of the usable range when idle will drop .1V to .2V when a motor runs and not supply the amount of current needed to operate the motor. The vertical travel shutter is charged by a motor that cocks the shutter and sets the mirror. When you meter, make an exposure, the film advances then the shutter gets charged. The mirror locking up then returning on the next push of the shutter button is the batteries building back up a little which is just enough to complete the shutter charging cycle.

Low power may not be the only possible cause but its the most likely.

Alkaline batteries when fresh read 1.56 to 1.6 volts on a volt meter. When the battery reads 1.51V it will barely operate a camera. A battery that reads 1.49V or lower needs to be replaced.

Happy shooting!

David Lyga · Jul 11, 2020

shutterfinger said:
Vintage SLR's are all mechanical for the shutter/aperture/film advance operations via levers, gears, springs, and the user's finger power.
Introduce meters, now an electronic power source is required if the sensor does not generate power when exposed to light. This is low current draw.
Introduce auto film advance, vertical shutter travel, auto focus and the like requiring more power.
This is all solid state devices and motors. Solid state devices require a specific voltage range to operate in but are current dependent devices. The electronics of these cameras will only drop the voltage .05V to .1 volt when fully activated on fresh batteries. Marginal batteries that are at the low end of the usable range when idle will drop .1V to .2V when a motor runs and not supply the amount of current needed to operate the motor. The vertical travel shutter is charged by a motor that cocks the shutter and sets the mirror. When you meter, make an exposure, the film advances then the shutter gets charged. The mirror locking up then returning on the next push of the shutter button is the batteries building back up a little which is just enough to complete the shutter charging cycle.

Low power may not be the only possible cause but its the most likely.

Alkaline batteries when fresh read 1.56 to 1.6 volts on a volt meter. When the battery reads 1.51V it will barely operate a camera. A battery that reads 1.49V or lower needs to be replaced.

Happy shooting!

Thank you and this does make sense, although I had not thought of this. To be honest, whether digital or not, I wonder why these cameras are made with so little leeway concerning the power necessary?

John Koehrer · Jul 11, 2020

^^^^What mr finger said. I've worked on AE 1's that would fire once and not fire again unless the battery rested for a minute or two. Just as mr. finger says when the battery was tested immediately after a successful cycle it was about .1-.2V low just enough to scuttle that second exposure.

David Lyga · Jul 11, 2020

John Koehrer said:
^^^^What mr finger said. I've worked on AE 1's that would fire once and not fire again unless the battery rested for a minute or two. Just as mr. finger says when the battery was tested immediately after a successful cycle it was about .1-.2V low just enough to scuttle that second exposure.

You know, this battery thing is rather interesting. I have a cheap digital camera that takes two AA batteries. That is nice because there is no need to charge. But, with alkalines, they last for maybe only 30 pictures (if most are taken with flash), The amazing part is that if they get 'expired' and I take them out and put them in my battery checker, they register practically brand new!! And ... to make this even more interesting ... if I take the 'expired' batteries OUT of the camera and let them sit overnight, the next day, I can put them back in the digital camera and get maybe five more (flash) pictures. But, if I had left them IN THE CAMERA they would not be good the next day for more shots.

However, with the Nikon N8008 the incompleteness is with the batteries at the beginning. Then, subsequent exposures are perfect (when the batteries SHOULD be more exhausted.) THAT, I do not understand.

shutterfinger · Jul 11, 2020

Don't trust battery testers. What they show good will work in a flashlight but not in a camera.
Batteries do strange things. When sitting idle with no load the chemicals inside react with each other giving them a little more life most of the time. Sometimes the inactivity results in a diminished current capacity then when used a little they provide more current kind of like stiff muscles the day after a heavy workout, they loosen up a little after some more use.

Think of batteries like water in a tank with the out at the top of the tank. The water is the current available, voltage is the pressure needed to push the water out. The pressure is sealed in the tank and when the outlet valve is opened the water flows out until the pressure is depleted.

Digital cameras have a constant current draw on the batteries when turned off as the camera memory has to have power applied to it to keep the settings, clock active.

If the 8008 continues to hang on first use with fresh batteries then its likely a mechanical problem or remote possibility its the electronics.

Edit: I just looked at the owners manual for a battery tester sold at Home Depot for $11. A AA cell will show good with a voltage of 1.125V ±.9V which is .4V lower than the minimum necessary to run a camera.
A low cost VOM will give you better results.

David Lyga · Jul 12, 2020

You are certainly correct when you say that "batteries do strange things". And voltage meters tell only one side of the story. My Nikon N8008, I am confident, has NO mechanical problems, but it has a chip problem. It has be 'informed' that it is capable of running a full shutter/mirror cycle without having to stop. That 'learning curve is completed with the first exposure and, for about one hour, it is retained. And you are correct with stating that, even if turned off, batteries very slowly drain from digital devices. This is why I remove them after use.

The Minolta electronic bodies can also have this problem, whereby if not used for a very long time, sometimes years, needs a 'reboot, in that several shutter passes have to be made before it will remember how to fire and meter properly. - David Lyga

Nikon N8008 funny problem

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