Nizo 801 auto B feature

[Sasounet]

Hi,

I am currently experimenting with my Nizo 801 "auto B" function. At first sight, it looks like it is working ok i.e. it will expose for a longer time if there is less light and a shorter time when I crank up the light.

However, the iris setting seems to have no effect. For example if I manually set the iris at f4, the camera will expose for 5 sec every frame. If I change the iris to f8, the camera still expose at 5 sec per frame. I would expect the time to go to 10 sec per frame...

Do I have a broken Nizo or is it normal behavior ? I know that the "auto B" feature use a different external light meter, but nevertheless it should take into account the iris opening...

If every Nizo behave like this, would someone more knowledgeable please explain what setting should I use for the iris.

Thank you.

[aj]

The B-sensor is outside the lens-optics. It is the eye-thing above the lens. So it is very unlikely it will take in account what the aperture is. These electronics are from the 70-ies. I.e. not bus-wiring with digital control. It is all analog and manual.

The same on the Bauers who swing out a sensor sideways which then monitors the light-level.

[granfer]

Do you have the manual for the camera? If not, you may be missing the important details. On this camera, the "Auto B" setting has to be used in conjunction with the "Shutter control " function to achieve the correct exposure control, in addition to ensuring that the special light cell is not obscured by anything (remove any lens hood).
Granfer

[71er]

Funny that there is nothing mentioned about it in the Nizo 801 manual.
I also had a look in the manual of the Eumig 881, which has the same feature and the same second light meter, and there it says that the aperture has to be set manually to 2.8 when a 100/160 ASA film is used, which suggests that when using a 25/40 ASA film (the camera can only read them two sensitivities) the aperture should be completely open - probably set automatically via the TTL control.

[granfer]

It IS in the Manual... page 20 "Automatic extended exposure system",
but easily overlooked if you do not read Manuals PROPERLY.

Also see... http://www.hostboard.com/forums/super-8 ... uto-b.html

[71er]

I only found the manual for the Nizo 801 macro and I assumed it would be quite the same with the Nizo 801. I read the section "Automatic extended exposure system" again and there is no mentioning of what the aperture is set on or should be set on when running the camera on "autom. B".

[granfer]

That's because you do not need to set the aperture, I think you will find that...
1. The camera opens the aperture fully regardless of the viewfinder indication,
2. The shutter is open until the correct exposure time is achieved, then it closes to move the film on and opens for the next exposure period.
The rate ( no of frames per second )is based on the received light, the film speed and the fully opened lens only.. the camera determines the FPS. Don't forget, this is for VERY LOW LIGHT USE only( and static subjects!). Believe me, it works beautifully.

[Sasounet]

That's because you do not need to set the aperture, I think you will find that...
1. The camera opens the aperture fully regardless of the viewfinder indication,
2. The shutter is open until the correct exposure time is achieved, then it closes to move the film on and opens for the next exposure period.
The rate ( no of frames per second )is based on the received light, the film speed and the fully opened lens only.. the camera determines the FPS. Don't forget, this is for VERY LOW LIGHT USE only( and static subjects!). Believe me, it works beautifully.

On most super 8 camera the aperture indicator (needle) is physically attached to the iris. (Don't know if it is the case for the Nizo) So if I manually set it to f8 the frame will receive less light than at f2 for the same "auto B" time exposure.

I think that "auto B" is design to work with the aperture set to automatic (where, because of the low light situation will open the iris fully) it then compute the exposure time assuming a totally open iris.

If this is the case, it is too bad as you have no control over the depth of field...

[granfer]

From my experience of this camera (several years ago) ... yes you have to focus carefully because of the depth of field problem., and you have to tripod mount the camera with a very good tripod. This low light facility does dictate the kind of STATIC subject; moving subjects that vary their distance from the camera are out!.

[71er]

If this is the case, it is too bad as you have no control over the depth of field...

You could trick the mechanism by taping a grey filter in front of the second light meter and then manually set the aperture accordingly. As long as the exposure times don't get too long for the automatic it should work and you get a greater depth of field.

[Jim T]

If the auto exposure light meter for the Auto B function is the eye above the lens, can I use an ND filter on the lens to knock the exposure down a stop? I got some footage back and there was just too much light though the lens, I was hoping for night scenes but it looks like early evening due to meter keeping the shutter open for too long.

[aj]

You can use a ND filter on the picture taking lens. This will reduce the light coming to the film.

Don't put it on the mini lens (glass droplet) of the measuring eye above the lens That would make the pictures even more brighter/over exposed.

[filmo]

I have this camera, and shot a lot of trippy stuff with the Auto B function.

Time lapse of the sun coming up, time lapse of moving cars on the freeway, etc.

I was curious just like you, and so I did some testing. Since the 801 loads from the rear, you can indeed look through the lens with the shutter wide open. I did this, and noticed that in cases where auto B would be necessary, the aperture blades are always wide open.

I did a really cool auto B shot of a candle in the foreground with streaky traffic lights in the background ( I set up my shot in front of a second-floor window and removed the aluminum screen so that I could get cleaner color through the window. I used the very longest end of the Schneider zoom, which was where I found the lens gave the best results anyway, but I wanted the background to be soft. I focussed very carefully and used a tripod, of course.
I lived on a busy intersection, so after auto B clicking away for 5 o5 6 hours in a darkened room I got about 15 seconds of the candle flame moving very quickly and melting down with streaks of unbroken car headlights and taillights in soft focus in the background. This was on Kodachrome, of course, so the colors were very nice. I ran that clip through a projector in an endless loop at a party. It was pretty cool. I spliced the clip back into a regular roll, but it's really dirty now, although not scratched in any way. There is some dirt that just won't come off with the film cleaner I use.

[Sasounet]

.
I was curious just like you, and so I did some testing. Since the 801 loads from the rear, you can indeed look through the lens with the shutter wide open. I did this, and noticed that in cases where auto B would be necessary, the aperture blades are always wide open.

I am sure the blades are always wide open when the aperture control is set to automatic... But if I set it to manual, does the blades stay wide open ? I guess I will check myself as soon as my film is finished. Thank you for the tip.

François