While more commonly known for their filters and their upcoming cine lenses, NiSi recently announced their new NM-180 Macro Focusing Rail. Focusing rails are essential pieces of kit for serious macro photographers that allow them to create images that might otherwise be impossible, but how well does the new NiSi NM-180 stack up? Maybe pun intended.
I’ve been using the NiSi Macro Focusing Rail for a few weeks now. The short version of this review is that for what it costs, it’s an extremely well-made device, that has some thoughtful design considerations and does exactly what it’s supposed to. In my opinion, it’s well worth what it costs. But how do focusing rails work and why do you need one?
Before we take a look at the issues of shooting macro that a focusing rail solves, let’s take a quick look at the NiSi NM-180 and its features. As I mentioned, the NiSi NM-180 has some thoughtful design features that offer the user a lot of versatility when it comes to how they want to use it.
First off, there are four feet on the bottom of it, meaning that you can stand it straight on a desk without having to go through the hassle of mounting it to a tripod and then levelling it. You can still attach it to a tripod, too, but you don’t have to. When you do want to, there is a 3/8-16? socket underneath with a 1/4-20? adapter allowing you to mount it to whatever plate you wish. And the feet are removable, too.
Another option for tripod-mounting the focusing rail is that the entire thing essentially has a built-in Arca Swiss compatible plate. So, if you’re using an Arca Swiss compatible head, you don’t need to bother with tripod plates at all.
On top of the carriage that runs along the rail is an Arca Swiss compatible mount (with a very nicely machined plate) into which you can mount your camera and lens. This head can also rotate a full 360? so that you can track towards or away from a subject or from one side of it to the other for capturing wide views of flat objects.
On each end of the NM-180 is a knob to rotate the threaded rod that runs the length of the unit. On one end is a simple round knob, while the other has a handle with a collapsible knob that makes it a little more obvious just how far you’re actually turning it each increment.
Each full revolution of the handle or knob moves the platform 1.25mm, allowing for some very fine movement increments. On the sides of the rail are two rulers to show you, in millimetres, exactly how far you’re moving the head, creating consistent and repeatable movements and results.
But why is this a big deal? Why do you need a macro focusing rail? Can’t you just move your tripod head or camera or subject and tweak your focus until you get it right? That’s what we do with other photography, right? Well, yeah, you can, maybe, but let’s take a look at that.
The problem with shooting macro is that you’re typically dealing with an extremely shallow paper-thin depth of field. This presents two big issues.
- It’s difficult to nail the plane of focus exactly where you need it to be
- You’re rarely going to get your whole subject sharp front-to-back because you just can’t get enough depth of field.
And this is where a macro focusing rail steps in. If you are just looking to pinpoint a specific part of your subject in a single photo, with the depth of field so shallow, it’s easy to miss your target (even with an autofocus lens), especially if handheld but even when using a tripod. A macro focusing rail lets you move your whole camera setup closer to or further away from your subject in very fine increments in order to shift the plane of focus exactly where it needs to be to capture the detail you want.
For the second problem, because of the movement that macro focusing rails allow, you can create a series of images at different distances from your subject, shifting the plane of focus through it as you shoot. These images can then be stacked together in post and masked in order to create a final image that shows a much greater depth of field and level of detail than you can get in a single shot.
Sure, you can stop your macro lens down instead of stacking, but even at f/32, most macro lenses still probably won’t give you the depth of field you need on an extremely close subject. And when your lens is stopped down that small, you also have to worry about things like diffraction.
The stacking side of things is what I’m mostly going to be concentrating on here because nailing a single shot is quite simple, but being able to move your camera smoothly and precisely in specific increments over potentially a couple of hundred images is a bit more of a challenge and is the real advantage of a macro focusing rail.
How it works (on a tripod)
Here’s the macro focusing rail mounted on top of my Manfrotto Element Carbon tripod with the Nikon D800 and Nikon 105mm f/2.8D AF Micro-Nikkor lens sitting on top. In front of it, I have a tiny subject, lit by a couple of Litra Pro LED lights. In this case, it’s an STM32 development board.
The NiSi NM-180 lets us easily move our camera forward and backwards in order to get what we want in focus. But you can see in this image, that when focused on the near row of pins on the STM32 chip on the board, much of the board is out of focus. Even stopped down to f/11, as we are in this image, the depth of field is extremely shallow when you’re this close to your subject.
This is where stacking comes into play. I can see here that my depth of field is about 1mm, and the NM-180 moves 1.25mm for each full revolution of the road that runs through the middle, so if I take a photo every half-turn of the handle (0.625mm) and keep shooting, I can get a series of images that cover the full focus range from the front to the back of the object.
So, we move our camera to bring the plane of focus to the nearest edge of what we want to capture, take a shot, turn the wheel half a turn to move it back 0.625mm, take another shot, half-turn, shoot, and rinse and repeat until our plane of focus covers the far side of what we want to capture. In this case, that required a total of 61 images.
While we don’t have a single image that has the entire object in focus, we do have a set of images that have every part of the item sharp and in focus at some point throughout the sequence. I exported each of the raw files out as jpgs after processing them, and then brought them into Photoshop as layers of a single canvas – I’m using Bridge, but you can do it from Lightroom just as easily. You could also import the raw files directly into Photoshop, but this takes much longer to process.
From here, there are two processes that you need to do. The first is to auto-align the images. While the tripod and NM-180 are pretty solid, when you’re dealing with such tiny objects and movement increments, you’re almost always going to get some slight lateral movement from shot to shot. Plus, you’re actually moving the camera forwards or backwards from one image to the next, so different objects will be slightly larger or smaller in different images as the camera moves towards or away from them. Aligning resizes and positions all of the images so that they fit on top of each other perfectly. This is just the nature of macro focusing rails and isn’t specific to the NiSi NM-180.
With all of the layers selected in Photoshop, choose Auto-Align Layers from the Edit menu, click Auto, and then hit OK. You can check Vignette Removal and Geometric Distortion if you wish, but do note that this will add a lot of extra processing time.
Even without those two options checked, the alignment process can still take a little while, especially with 61 large images. But when it’s completed, the second part of the process actually creates your stacked images. It’s the next option down on the Edit menu, Auto-Blend Layers. When the box pops up, choose the Stacked Images option and hit OK.
Now, as you can see in the image below, Photoshop isn’t great at stacking. It’s ok, but not great. I’ve tested this in multiple versions of Photoshop from CS6 up to the very latest Creative Cloud version and the results are pretty similar despite having plenty enough images to cover the full range of focus. Sometimes, Photoshop just doesn’t quite catch the edges properly in this pretty-much-entirely-automated process.
For this kind of stacked macro image, especially if you have a higher resolution camera, you’re often best shooting a little wide, so that you can crop the outer edges that aren’t blended quite as well as one might hope. But even in the main part of the image, you can see that that while it does a reasonable job, Photoshop doesn’t always quite nail things perfectly. Pay particular attention to the top edge around the 8MHz crystal.
If Photoshop isn’t working well for you, Affinity Photo also offers focus stacking and there are plenty of other dedicated stacking applications out there, too, like Helicon Focus. Blending the images together manually is often going to produce the absolute best result, although this obviously takes the longest amount of time.
Sitting on the desk
As well as mounting it on top of a tripod, the NiSi NM-180 Macro Focusing Rail can simply be placed on the desk. This might limit your subject options, somewhat, as you can’t really tilt the rail (or the camera). You’re moving horizontally only (or at least parallel to the surface on which the rail is sitting). So, whatever you’re going to photograph needs to be at that same horizontal plane relative to your lens and sensor.
For some objects, though, this will work quite well, as is the case with this cactus, which was shot as a sequence of 24 images.
One cool side effect of stacking this way is that it allows you to get some pretty cool focus racking shots that you can turn into a little video sequence (once auto-aligned in Photoshop). Quite handy if you’re trying to shoot some high-resolution b-roll of teeny tiny subjects that aren’t constantly in motion and you want to rack from one target to another. As you get precise control over exactly how far the camera moves from one shot to the next, you can get some extremely smooth focus racks this way – much smoother than you can get by trying to turn your focus ring manually.
You can see in the animation above that once the images are aligned, they fit together very well, showing virtually no camera movement and very little perspective shift as the camera moves through the tiny scene. Exactly how much perspective shift you’ll see will depend on both the scene you’re shooting and the lens you’re using. If your subject is practically touching the lens, then you’ll notice more than if you’re shooting with a longer focal length from a greater working distance.
The image above was aligned and then stacked in Photoshop in the same way as the previous image of the STM32 development board but here I’ve done some manual tweaking to compensate for Photoshop’s shortcomings where it couldn’t quite get the edges right. It’s still not perfect, but you can see how the NiSi NM-180 and other focusing rails allow you to capture beyond the depth of field limitations of a single shot when shooting macro.
Macro focusing rails aren’t the only way to create stacked images. You can also rack the focus on your lens instead, but depending on the setup you’re using, you often can’t quite get the fine increments required in order to achieve a thorough depth of field range on the entire scene. Some cameras, like my Panasonic G80 and GX80 cameras, also have a focus stacking feature built-in, but they’re often limited to lower resolutions – like 4K, because they’re essentially shooting a video clip and then creating the final image from the recorded frames.
But, choice is good. Even if you do have those other options at your disposal and you’re pleased with the results, macro focusing rails are another great tool to add to your arsenal. And if you shoot macro often, it’s one you’ll likely find yourself using more often than not once you get one. And the NiSi NM-180 Macro Focusing Rail is a good option to go for.
Pros & Cons
- The body is essentially one long Arca Swiss compatible plate, meaning you don’t need a separate plate to mount it to a tripod (although the option is there)
- It has (removable) feet so that you can set it on a flat surface to photograph a subject without having to deal with a tripod
- It moves smoothly, consistently and accurately, with easy to read measurements
- The camera mount can pivot a full 360 degrees to sideways tracking or mounting a second NM-180 rail on top of the first to offer front-to-back and side-to-side movement simultaneously
- The measurements on the side are very easy to read to see exactly how far you’ve moved
- Small and compact for easy packing when you want to take it out on location to photograph macro in the wild
- The central rod rotates smoothly and cleanly with very little backlash
- The Arca Swiss compatible plate for the camera is very nicely machined for easy mounting/removal without having to use tools or coins
The only real con is that you don’t really get the full 160mm of advertised travel. At the end of the rail where the handle is, the carriage hits the handle preventing it from going any further. Even with all of the carriage knobs out of the way, it still doesn’t go all the way to zero, stopping around the 11mm mark.
At the other end, it stops around the 141mm mark. So, your actual travel movement is closer to 130mm in total and not the advertised 160mm. In reality, though, it doesn’t make much difference. If I’m using a macro lens, then I’m shooting something tiny. I’m likely never going to need anywhere close to a 160mm range over movement anyway (or even 130mm). So, it’s only a negative from a technical standpoint, rather than anything that would impact the majority of users in the real world.
Is the NiSi NM-180 the cheapest macro focusing rail out there? No, it’s not. There are some very cheap units out there, like this one. But those ones are very cheap for good reason. They’re absolutely terrible. I actually bought the one I just linked a year ago and after taking it out of the box and trying it just once, I realised just how useless it is and haven’t touched it since. With macro focusing rails, you generally get what you pay for and the NiSi NM-180 is worth every penny of its $129 price tag.
There are also more expensive and much more expensive macro focusing rails out there, too, which offer even greater levels of precision and features – like separate dials for coarse and fine adjustments of the camera position. But the NiSi holds a solid place in the middle. It’s good enough for some serious macro work but inexpensive enough that it’s attainable for the majority of potential macro addicts.
Overall, the NiSi NM-180 Macro Focusing rail has performed very well for me. I can see myself using it fairly regularly in the future when I need to photograph tiny detail macro shots, which seems to be happening more and more often lately. I definitely need to start looking into some better macro stacking software than Photoshop, though. I’m open to suggestions if anybody wants to drop any in the comments!
This NiSi NM-180 Macro Focusing Rail is available to buy now for $129 and is already shipping.