What Is A Macro Rail?

A macro rail is a mechanical rail system that allows you to move a camera fore and aft, or left and right, in extremely small and precise movements.  Depth of field can be incredibly thin when working at close distances with a macro lens.  Precise focus can be tricky to achieve, but with a macro rail, and the help of live view, it’s easy to fine tune the exact point of focus.  A system of gears ensures that you have incredibly precise and repeatable control.  Given the shallow depths of field in macro photography, focus stacking os a technique that is often necessary in order to get detail throughout your subject.  With a macro rail, it’s easy to shoot all the photos needed for your focus stack in a repeatable manner by using the measuring scale on the rail.  Take your shot, advance the camera a tiny amount, then take the next shot.  All of the shots can then be combined together automatically in Photoshop, or using specific programs like Zerene Stacker.

Why not just rotate the focus ring on the lens?

Good question!  The problem is that some lenses have a very small focus throw that will change the focus position too much, even with a tiny change in the focus ring position.  These are lenses where a macro rail, sometimes called a focus rail, will be especially important.  Many lenses also exhibit a large amount of focus breathing which actually causes a change in the focal length when turning the focus ring.  Even though a lens might say it is a 60mm macro lens, it might actually go from 57mm to 63mm depending on the position of the focus ring.

 

 

Additional Reading

  • What Is A Macro Lens?
  • Essential Gear For Macro Photography
  • What Does Focus Throw Mean?
  • What Is Focus Breating?

 

what is a macro rail

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