Building An Ultimate Focus Stacking Rail

Introduction

It has been an unending quest to build an automated focus stacking rail for many focus stacking enthusiasts, ranging from modified manual rail to actually CNC machining their own rails. Every now and then, there will be a post in many popular online macro photography forum, Facebook groups, etc, about making an automated rail for focus stacking. Most of these posts and ideas are sound and usable, but they also suffer from some key aspects, namely precision and stability. Though these imperfections can be fixed by using powerful focus stacking software, the software alignment function sometimes can introduce some other artifacts -- distortion, streaking at edges, etc. These artifacts might not be a problem for single frame stacked image, they could pose potential problems for stack and stitch.

Solution

As a stacking rail designer, one thing I have learned is: it is very difficult to make a high precision rail without heavy investment of high precision tools. One solution that I have used for SR-90 rail is to use a readily available industrial precision part, the linear guide rail, as backbone of the rail. This definitely solves many issues plagued by my early attempts of using two guide rods.

So with the idea of taking advantage of readily available components that are machined at high precision and tolerance and the winner is THK KR2001 or its compatible rails. The THK KR2001 is used in industrial automation and has high precision and repeatability. Best of all, there are plenty of surplus supply of such rail, all that needed are some components to convert it to a stacking rail.

Lets Make It Happen

THK KR2001 and its compatible rails are designed for industrial use, to adapt it to focus stacking, there are a couple of things to do: mount a step motor onto it, couple the motor with leadscrew, mount camera on top of the rail. All of these mechanical components can be purchased on our website here.

Besides these mechanical parts, you would need focus stacking controller to make it happen which can also be purchased from our website.

Step 1: Put base stands on to the rail

There are two M3 threaded holes on the base stand and they are used to attach the rail onto it.