RPi HQ Camera: 4.8 mm Computar Video Lens

The Big Box o’ Optics disgorged an ancient new-in-box Computar 4.8 mm lens, originally intended for a TV camera, with a C mount perfectly suited for the Raspberry Pi HQ camera:

RPi HQ Camera - Computar 4.8mm - front view
RPi HQ Camera – Computar 4.8mm – front view

Because it’s a video lens, it includes an aperture driver expecting a video signal from the camera through a standard connector:

Computar 4.8 mm lens - camera plug
Computar 4.8 mm lens – camera plug

The datasheet tucked into the box (!) says it expects 8 to 16 V DC on the red wire (with black common) and video on white:

Computar Auto Iris TV Lens Manual
Computar Auto Iris TV Lens Manual

Fortunately, applying 5 V to red and leaving white unconnected opens the aperture all the way. Presumably, the circuitry thinks it’s looking at a really dark scene and isn’t fussy about the missing sync pulses.

Rather than attempt to find / harvest a matching camera connector, the cord now terminates in a JST plug, with the matching socket hot-melt glued to the Raspberry Pi case:

RPi HQ Camera - 4.8 mm Computar lens - JST power
RPi HQ Camera – 4.8 mm Computar lens – JST power

The Pi has +5 V and ground on the rightmost end of its connector, so the Computar lens will be jammed fully open.

I gave it something to look at:

RPi HQ Camera - Computar 4.8mm - overview
RPi HQ Camera – Computar 4.8mm – overview

With the orange back plate about 150 mm from the RPi, the 4.8 mm lens delivers this scene:

RPi HQ Camera - 4.8 mm Computar lens - 150mm near view
RPi HQ Camera – 4.8 mm Computar lens – 150mm near view

The focus is on the shutdown / startup button just to the right of the heatsink, so the depth of field is maybe 25 mm front-to-back.

For comparison, the official 16 mm lens stopped down to f/8 has a tighter view with good depth of field:

RPi HQ Camera - 16 mm lens - 150mm near view
RPi HQ Camera – 16 mm lens – 150mm near view

It’d be nice to have a variable aperture, but it’s probably not worth the effort.

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