Focus stacking Technique
I have asked myself these questions a lot, and perhaps one or more of them has crossed your mind as well:
- My depth of field is too shallow, my subject is not sharp, how can I fix this?
- I’d like to create new compositions and no longer be limited to taking insects with a perfect profile in order for them to be completely sharp.
- I’ve heard of a druidic science of image stacking but don’t know how to do it.
- I’m touching on this Celtic sorcery with my fingertips, but my results in Photoshop always have blurry areas that I don’t like.
What is Focus Stacking ?
Focus stacking is a technique used in various fields, such as product/packshot photography, landscape photography, and also macro photography, to capture the maximum amount of detail, from the smallest insect to the fine textures of a leaf. This method involves taking several photos of the same subject, each with a different (or shifted) focus, and then combining them into a single image. This process allows for the creation of an image where the entire subject, from the foreground to the background, is perfectly sharp, unlike a traditional shot where the depth of field is limited.
Here’s an example with this ladybug, which would not have been fully sharp with a single shot:
Even with a small aperture (for example, f/16 or f/22), it can be difficult to achieve a sharp focus across the entire subject, and the lost brightness requires compensation with shutter speed or ISO.
Focus stacking solves these issues by allowing you to combine multiple images taken at a larger aperture without sacrificing shutter speed or ISO. This way, you can capture each part of the subject in sharp focus, creating a more detailed image.
Advantages of focus stacking
- Achieve a large depth of field even in macro photography without loss of quality
- Capture maximum details
- Have a perfectly sharp subject when moving out of the profile composition (this likely comes from my passion for comics, where no perfect profile is ever present)
Disadvantages
- It takes longer than a simple shot, with the risk for outdoor photography that the subject or the background may move, which can cause the focus stacking to fail.
- It requires post-processing (which could be a disadvantage for some).
- This technique (like many others) requires practice, especially when shooting handheld.
How to achieve Focus Stacking in macro photography?
The shooting
Since we are talking about macro photography, a macro lens will be the best but it is also possible to take pictures with a lens mounted on elongated rings or with a lens that allows you to increase the magnification factor.
Preferably, you will need a tripod and a remote control but it is still possible to do focus stacking handheld (many Instagram accounts are dedicated specifically to this discipline and use this technique handheld with a flash + diffuser, I let you discover them)
I personally use a 105mm macro lens or a 56mm macro and a remote control, a tripod and a macro rail from the NISI. Here are some pictures of the rail used:
The goal is to install the camera on this macro rail. Position the camera as shown below, turn the rotating head to move your camera forward (or backward). The rail is designed for a movement of 1.25mm per turn.
If you are interested in this product, please feel free to click on the affiliate link NISI or at the end of this article, go to the macro category, you will find the reference NiSi NM 180 micrometric macro rail, you do not pay more but you contribute to developing my activity so everyone is a winner.
I also recommend the NISI filters, I use the CPL and ND filters for my long exposures but I’ll keep that topic for later. This rail allows for great precision in focusing (the essential element for successful focus stacking). It is robust and reliable (it resists the Breton climate, next test in the Peruvian Amazon), installs quickly and is Arca Swiss compatible.
Some advice on the settings:
- Choose a medium aperture (f/5.6 to f/16) to maximize the depth of field of each image (avoid values beyond f16 which can deteriorate the image). I advise you to do a few tests already, an aperture of f5.6 often allows me to have very good results and to gain in brightness but I started with smaller apertures.
- If you are on a tripod, use a remote trigger or the self-timer to avoid vibrations of the camera.
- Use a low ISO to avoid maximum noise.
- No autofocus
- Remove stabilization if your camera is mounted on a tripod
It will therefore be necessary to “sweep” the subject (or the area that you want to obtain in focus) from the closest point to the furthest point. Place your focus as close as possible to the lens and gradually advance the device while triggering, stopping slightly after the desired final area. In the following example, three images of the rectangle are taken to obtain a completely sharp rectangle (I1 = image1, I2 = image2, I3 = image3 and Result):
I1
I2
I3
Résultat
There are several ways to perform this technique:
- Handheld: stay stable and use the continuous shooting function. Be careful, there are many missed shots if you haven’t practice it before.
- With a tripod and a macro rail, my favorite
- With a tripod and using the camera’s built-in focus shift function (I personally use a Nikon camera that allows automatic focus ring shifting; some cameras even offer the option to automatically combine the images).
Post-Processing
The easiest way, if you have an Adobe subscription, is to use Photoshop with the auto-alignment and merging options. You can then manually touch up certain areas but I encountered some flaws with it.
I recommand specialized tool like Helicon Focus which is reference in the field. These software programs allow you to process your photos quickly and effectively for nearly perfect stacking. This application offer powerful algorithms that ensure each photo is aligned and processed consistently, like in this wild orchid example:
Few tips
First of all, like the most technics of photography, this requires practice, especially when photographing outdoor insects, as you can never be sure the subject will stay in place, and thus, succeed in focus stacking. It’s also good to know that the higher the magnification ratio you will use, the greater the difficulty you will have, so it’s better to start with an appropriate ratio, like 1:1.
For this article (and also for my learning), I conducted tests indoors with a lightbox, using my first camera and my 105mm macro lens at a 1:1 magnification ratio. Opposite, my subject with the lightbox and after, my first result:
Here’s a second example with a higher magnification factor:
The biggest problem I encountered with my first results was the depth of the subject. If an element is in the foreground, and the focus needs to be on that element and on other just behind it, there’s a risk of blurring at the transition, as shown below:
The second issue occurs, particularly when shooting handheld, when you try to go too fast. A blurry line will appear if you move the camera too quickly; in other words, there will be a part of the subject that didn’t fall within one of the depth of fields.
Conclusion
Focus stacking is a technique that allows you to capture macro images with exceptional clarity and precision. It requires skill to avoid blurry photos but the results after a few weeks are breathtaking.
I personally chose to invest in good equipment, and quality software is essential to achieve the best results. By working with leading brands like NISI for the macro rail and Helicon Focus, you’ll have the necessary tools to take your macro photography to the next level.
Here’s the affiliate link if I haven’t already convinced you: NISI
Would you like some ideas for subjects for your upcoming experiments?
