Why do you need focus rails for ultra macro photography and not just a regular tripod head? To perform focus stacking; a series of perfectly aligned shots, each with a slightly different focus point. Stacking software then blends the in-focus areas from each photo into a composite image that should be in sharp focus from front to back. The macro focus rail lets you dial your camera forward in the precise increments needed to keep the shots aligned. The focus rail is especially useful in super macro photography with reversed and stacked lenses where the depth of field is so shallow that the lens itself cannot focus on the entire subject from front to back.
Macro focus rails aren’t just for focus stacking. If you do tripod mounted macro photography often, a focus rail is very helpful for precisely framing high magnification shots. Achieving the same tight framing with a regular tripod head is not precise enough and can take too long with live subjects.
For most of us, the problem when shopping for 4-way macro focus rails is that high-end units cost around $600, which seems absurd for some pieces of metal. The purpose for such equipment is for photographing small dead subjects under extremely high magnifications with focus stacks sometimes exceeding 150 shots. Here, only the most precise movements with no wiggle can deliver the perfect alignment needed, and the macro focus rails compared here aren’t up to the task.
That’s not the type of super macro photography that I do, nor what I expect most of you are looking for either. I use a focus rail when I find a live bug in my garden that seems like he’ll sit still long enough for an indoor focus stack of between 10-30 shots. That means I may only get a minute before he flies or scurries off. Based on this, I’ve chosen to compare 2 of the most common macro focus rails found online. The Velbon Super Mag Slider and the Neewer 4-way Macro Rail Slider are two completely different designs at different price points. I discovered that each has its strong suit, and they don’t overlap greatly in capability.
Velbon Super Mag Slider Macro Focus Rail (~$120)
The Velbon’s design is so tight and sturdy that there’s no play between parts, which means there’s virtually no camera wiggle. The camera wiggle that I did get when sliding my camera forward was from the tripod itself with my heavy Nikon D810 atop. The adjustment knob is tight, and gives tiny precise movements when turned. A quarter turn moves the camera about 1 mm. The Velbon has 6 cm of travel front to back, and 3 cm side to side.
What it’s good for
The Velbon is constructed well with very little wiggle and very precise adjustments. The precise adjustments make it easier to achieve a perfect focus stack without the blurred bands in the final image where slices of focus were missed. The Velbon is best suited for more studio-type work where the subject will remain still for long periods. That doesn’t always mean dead bugs impaled on a pin; I’ve used my Velbon for compliant models like Stinkbugs and Tortoise Beetles. It’s also better when working at super magnifications of 3:1 or greater of tiny subjects where high precision is more important. At those magnifications, even an adjustment of 1mm can shift the frame a significant distance.
What it’s not good for
Ironically, the Velbon’s precision is it’s Achilles’s heal. Because it takes many turns of the knob just to move the rail a small distance, the Velbon is not well suited for situations that need quick framing. An example is a live bug that decides to move itself a few centimeters after you’ve already framed the shot. By the time you’ve moved the slider that distance to reframe, the bug has probably already moved again. Also, while the front to back focus rail offers a generous 6 cm of movement, the lateral focus rail only has 3 cm of total travel, which really only equates to 1.5 cm in either direction. If the bug decides to crawl an inch to the right after the shot has been framed, the Velbon lacks enough sideways travel to reach it, so you need to pick up the tripod to reposition it.
Available here:Velbon Super Magnesium Slider, Macro Rail
Neewer 4 Way Macro Focus Rail Slider(~$24)
The Neewer is very inexpensive with excellent range of motion, very fast adjustment, less precision and more wiggle. The construction quality is good for $24, but not in the Velbon’s league. The Neewer has a whopping 10 cm of travel on each axis. A quarter turn moves the camera about 5 mm, and the adjustment knob is loose enough that you can quickly span 10 cm in just a few seconds. Each focus rail has a friction adjustment knob to make movements slower and more precise. Movement of the rails is not completely smooth with small bumps along the way.
What it’s good for
What the Neewer lacks in precise adjustment and sturdy build, it gains in adjustment speed. Precision doesn’t matter if your bug has flown off before you took the shot. The $24 Neewer is best for situations where fast framing is needed, or the bug is only likely to stay still briefly.
What it’s not good for
The Neewer is less suited for intricate focus stacks of completely still subjects because its less precise adjustments require a lot of concentration to move in small increments. When shooting at super magnification, the gritty movements can make it difficult to maintain perfectly aligned frames. During adjustment there’s noticeable camera wiggle. However, the wiggle can be mitigated by waiting a few seconds between shots, which is proper stacking technique regardless of which focus rail you’re using. Camera weight will affect how much wiggle you experience, and the focus rails in this test had to contend with my hulking D810.
Available here: Neewer Pro 4 Way Macro Focusing Focus Rail Slider
For shooting intricate focus stacks with completely still subjects, the Velbon is by far the best option with precise movements and sturdier construction. But its adjustment is far too slow to frame shots of subjects that won’t stay still for long, which is where the Neewer shines. The Neewer, however, is less precise and has rough adjustment. The best option for you should be clear based on what you shoot most. However, what if you shoot all around macro and can only choose one? I’d actually lean toward the far cheaper Neewer. It’s better for fleeting shots of live subjects, and though rough, can get by with enough precision for intricate focus stacks if you invest some extra concentration.