Extreme macro photography with Novoflex Castel-M first impression

In another post, I reported on the AstrHori 25mm/2.8 2x-5x Macro, which offers a completely different introduction to the world of macro photography. The Castel M makes this a little easier.

Introduction

For close-up and macro shots, the depth of field becomes so small that it’s almost impossible to achieve the desired depth of field with just one exposure or aperture. The latter, in particular, leads to further problems due to diffraction blur. Focus bracketing is therefore recommended, with the images later combined in special software.

Especially with Olympus cameras, you have the option of doing focus bracketing handheld with a flash. But generally, you’ll use a tripod and a macro slider to gradually move the entire camera and lens combination.

I recorded a video about it:

Novoflex Castel Q

The Novoflex Castel Q is a focusing slider that has served me well for a very long time. Its rail, like the camera plate, is Arca-Swiss compatible. I’ve used the slider quite often, especially in combination with my “mushroom tripod,” a Berlebach Mini.

But in combination with the AstrHori 25mm/2.8, the slider reaches its limits, because even with the Castel Fine, the smallest feed rate is about 1/4 mm. That sounds very low, but for example, with an ABM of 2:1, we’re talking about a sharpness of about 0.24 mm at f/5.6. This means that this combination is already at its limit at 2:1, especially when we’re talking about larger scales.

Options

There are macro sliders from both AstrHori itself and, for example, from Niss, which allow a feed rate of 0.05 mm for the AstrHori and 0.01 mm for the Niss. The latter would be sufficient to allow a movement smaller than the depth of field, even at a magnification of 5:1.

Both macro sliders are already in the range of approximately €150 and almost €200, respectively, and have corresponding scales that would allow this tiny advance.

But you have to concentrate on the advance, and that with perhaps over 100 shots needed for a focus stack. And I’ve already discovered this with the Castel Q and the Castel Fine: it’s very difficult.

Novoflex Castel M

The macro slider is designed precisely for such purposes, i.e., extreme macro shots up to a magnification of 5:1. Its rail and camera plate are also Arca-Swiss compatible (a Q mount is apparently on top). However, after initial research, I had to swallow a bit about the price, because €570 for a macro slider is quite steep.

Almost like the other macro sliders, it has a dial on the back that allows the camera to be moved very precisely. A full rotation of 0.8mm is all we’re talking about, and a single division of movement moves the camera by only 0.01mm.

Novoflex specifies a depth of field of 0.037mm at 5:1 and f/4.0, while another calculator specifies 0.055mm. In any case, the smallest movement is sufficient to handle image scales of 5:1 with a calculated overlap.

On the back of the dial is a switch that allows you to set image scales between 2:1 and 5:1 on the macro slider. The dial then clicks into place at the corresponding intermediate steps depending on the image scale. Each full rotation of the dial moves between 12 and 45 individual positions.

You still have to manually adjust the feed rate, but the clicks make the entire process much easier. You simply continue turning until the next click and then take the picture.

According to the documentation, the distances are calculated for a depth of field of f/4.0, which I consider a positive, because at 4:1 and more, even f/5.6 can sometimes cause blur.

The Shots

For such image scales, a sufficiently stable tripod is a must. You should also manually adjust the exposure once, and the same applies to white balance. And for assessing the sharpness, I recommend an external monitor.

A cable release would also be useful to avoid touching the camera as much as possible. However, when taking a stack, I noticed that some blur was present in the individual shots, probably due to movement/vibration. Therefore, from now on, I generally use a self-timer with a 2-second delay. This is at least sufficient to allow the combination to settle down a bit.

Number of shots as another challenge

With such extreme macros, you quickly end up with a series of 100 or 200 shots for a focus stack.

The number of shots naturally depends on the magnification and the depth of the subject you want to capture in focus. Nevertheless, I generally use the electronic shutter here to minimize wear.

Keeping camera noise to a minimum is important. And things like rolling shutter or banding are unlikely to occur here.

The other challenge arises from the large number of RAW files. It’s not uncommon to have a hundred or more shots per shot (stack). However, this would be a good opportunity to generate DNG files from the base images. This saves a significant amount of hard drive space without having to make too many compromises.

Conclusion

The Novoflex Castel-M is a precision tool and worth the money because it significantly simplifies the process of taking such shots. After my experiences with the Castel-Q and the Castel-Fine, I would probably have been annoyed if I had purchased the AstrHori or Nisi focusing slide.

However, one point of criticism remains: why such expensive focusing slides don’t even come with a protective case.

For my part, I still need to learn how to use the Helicon Focus software I use better, as I noticed the typical “clouds” in some places during my first attempts.

What do you think of the Castel-M? Comments welcome.

ciao tuxoche