Nizo: converting to manual ISO/ASA setting

Idea to give a Nizo manual ISO setting (WARNING: doing this without indepth knowledge of this camera and precision measurement tools e.g. for lightmeter adjustment and others, gives unpredictible results and may harm your camera!)

Looking at the way the speed notch reading system works in a Nizo 561 it may be easy to adapt this to a manual system. The Nizo 801 has the same mechanism.

As you can see in the picture the notch is 'read' by the cartridge pushing the red highlighted part further in the shorter the notch (slower the film). This in turn rotates the cog which adjusts the reading from the light meter to set the correct exposure. So basically it is this cog that sets the exposure level.

By removing this highlighted part and the accompanying spring, the cog is free to turn. If a hole were drilled in the casing (easy enough as this can removed from the camera) a knob could be attached to the cog.

The best bit is that this cog actually turns further anti clockwise than the original mechanism allows, but still gives correct readings.

The original mechanism would read from less than the shortest notch (10/16 ISO) to almost, but not quite, 250/400 ISO as the 'notch reader' only pokes out far enough to measure a notch with an 'x' dimension (see Super 8 Cartridge Notch Ruler) as small as approx 8.5mm (the 'x' dimension of 250/400 ISO is 7.62mm and 400/640 is 5.08. This 'x' dimension is marked on the picture in Yellow.

However since you could manually turn the cog that bit further anticlockwise and still get a valid reading you could go at least up to the equivilent of the 400/640 ISO notch.

The only real difficulty I can forsee are getting the correct scale on the camera and giving the ISO knob a satisfactory amount of resistance to turning it, so it is comfortable to turn but will not move whilst filming.

Source: danpuddick posting on filmshooting.com forums. Reproduced here with his permission.