This is not the right rail for everyone but if you want to create focus stacks of larger objects like flowers or still life scenes this rail will fit the bill perfectly. It will give you 200mm (8in) of movement from one end to the other. If you plan to do high magnification stacks of small subjects stick with the standard rail as its shorter length makes for a more rigid system. But if you want to capture larger subjects this is the rail for you. Even with this extended length it still maintains the same linear accuracy as its shorter cousin. The image below gives an idea of what is possible.
Many thanks to Bob Coates for the use of his images.
The image above is a focus stack of 48 combined images. It was captured using the Extended Length Macro rail and StackShot controller.
The image to the left is the first image in the stack. As you can see the depth of field for this image is quite shallow.
The Extended Rail
Keep in mind when creating a focus stack that is the full 200mm that you will loose the periphery of the image as the rail moves from back to font.
The extended rail, like its shorter cousin is made from black anodized aluminum and stainless steel rails and fasteners.