Nikon PB-4 Bellows with Stepper motor

I was long playing with the idea of adding a stepper motor directly to a Nikon PB-4 Bellows to allow macro photography and stacking photos for a deeper depth of field. The Nikon PB-4 is a very sturdy designed bellows from the 1960’s. It has 4 linear tracks. The bellows can be moved to increase magnification. Once that is set, the whole bellows, including the camera can be moved by a third knob. This makes the PB-4 ideal to be modified. I could have gone the easy way: buy a track, mount the PB-4 onto the track and finished. That works, however I wanted to make also something nice.

The concept is relatively simple: Create a base plate. Fix a stepper motor onto the base plate. Connect the stepper motor shaft to the shaft of the bellows. Add a controller and trigger for the camera. The result should do the following: program the increments and numbers of pictures to be taken. Run the software: Stepper motor will move, stop, trigger camera, move, stop, trigger camera. With special software you can stack all photo’s and that should give you a picture with a very high DOF. (take into account this is Macro photography)

Let’s Start:

For the base plate I took a 100x100mm aluminium plate, 12 mm thick. The first thing I did was milling 3mm deep slot in the contour shape of the PB-4 base. 1/4″ hole was drilled at correct position. The PB-4 will sit precisely in this slot and with a 1/4″ bolt the PB-4 can be mounted onto the base plate. Front and back sides of the base plate I milled 2 deep slots of 16x6mm: this will be used to mount the base plate onto a T-track with 2 clamp down knobs.

Stepper motor and gear. Nema 17 plate with 2 M4 holes added, base plate and tripod mount. Nikon PB-4 with exposed shaft.

On the bottom side of the base plate I drilled 1×3/8″ hole. A 1/4″ conversion screw is situated into this hole. This to protect the screw-thread. This 1/4″ screw hole gives me the possibility to mount a Tripod plate, incase I want to use the rig outdoors.

On the side, where the PB-4 shaft is located, I drilled 4 holes: 2xM3 and 2xM4. M4 bolts are used to mount a Nema plate to the base plate. This must be very sturdy to avoid play. The M3 holes are used for 2 of the 4 rods that hold the stepper motor in place.

Once I finished all milling and drilling, I gave the base plate a wrinkle paint coating. It is the same as Nikon used on the PB-4 metal parts. The base plate sits on a wooden base with a T track. It allows for quick adjustment of the whole rig.

The stepper motor is connected to a gear box with a 5:1 ratio. The M3 rods hold the stepper motor and gear box. The bottom two rods are screwed all the way into the base plate. The top 2 rods are secured with two M3 bolts onto the Nema plate. (Nema 17 and equal stepper motor) The shaft of the PB-4 is connected to the stepper motor via a flexible shaft coupling: the PB-4 has a 6 mm shaft once you removed the aluminium knob.

Base plate painted in wrinkle paint, Stepper motor mounted. Wooden base plate with T rails.

The baseplate with bellows sits onto a wooden base plate with the T track.

The controller for stepper motor and triggering the camera I had to outsource. I am sure that with an Arduino and some software know-how this can be done very cost effective. To stack photos I used HeliconFocus.

The first results are promising. With shorter days and current Covid situation this is a nice project to discover the world of Macro Photography. All materials can be found on auction sites or at OpenBuilds.

A 2mm End Mill

If you have questions: please contact me.

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