Following on from Dave Smith’s excellent and very impressive demonstration of macro photography last night (2nd April.)
Dave demonstrated using the Olympus mirrorless camera with built in focus stacking software. The Olympus has two types, which I will call the automated max-8-shot mode and the full-stack mode. Dave was using the full-stack mode which can take hundreds of RAW or JPG images in one stack.
Other mirrorless cameras have a similar full-stack mode, e.g. the Fuji X-T2/3 allows up to 999 frames at 1 to 10 steps at 0-10 second intervals.
I have used focus stacking techniques for several years but I don’t do a lot of it and certainly not at the microscopic level that Dave does.
However I thought I would just add something that might not have been too clearly understood last night.
The camera settings
- Set the camera on a tripod and put the exposure into manual mode
- The aperture, shutter and ISO setting as required
- The focus is set to the nearest point to the camera that is required to be in focus
When you focus stack you have three further parameters to consider.
- The number of frames you want to take
- The size of each step between frames (the very short distance the focus is moved between frames)
- The interval in seconds between frames. Useful to allow time for a flashgun to recharge before the next frame is attempted
The software built into many mirrorless cameras makes these last three parameters very easy to set up and offers hands-free control of the camera as Dave showed last night.
DSLR Focus Stacking
The question arose on how non mirrorless cameras, i.e. DSLR cameras, could focus stack. Dave mentioned using a rail to laboriously inch (or should I say millimeter) the camera closer to the subject between each shot. This was the way it used to be done and may still be done by some. However it is not the only solution.
Manual DSLR Focus Adjustments
I have often successfully created macro shots of flowers using a DSLR by simply turning the lens focus ring by hand between shots. Typically I needed only around 5 to 10 frames. I would do this a few times for one flower to give me the best chance of success. It requires some guess work on how little to turn the focus ring between each shot. A small aperture (e.g. f/16) gives the best chance of each shot having enough of the flower in focus for the stacking software to build a good result. If you take a step too large the image can end up with an out of focus section in the middle of the image.
Before starting I would first focus on the front of the flower then turn the focus ring until the back of the flower was in focus. That way I could see where the focus ring would start and end and estimate how many frames and step size I would need. A solid tripod , live view and a gentle touch prove useful.
This technique also works for landscapes where often only 2 or 3 frames are needed.
DSLR Remote Control Stacking
Another option is to tether the camera to your laptop/PC/mobile phone and use an application program like Helicon Remote to fully automate the process. I have no experience of this application but it appears to offer even more than the mirrorless cameras offer, e.g. it calculates the number of frames and step size for your lens/aperture. This may only work for (most) Nikon and Canon cameras that support tethering.
Dave was using an aperture of f/5.6 for his Olympus four-thirds camera. If you have a larger sensor camera, e.g. APS-C or full frame, this will equate to a similar DoF of around f/8 or f/11 so do try stopping the aperture down and experiment with your lenses. The smaller the aperture (e.g. f/16) will give greater DoF and need fewer frames with larger steps. Going smaller might result in some degradation from diffraction but I have never really noticed this with my flowers when using a good quality lens, however at the ultra small subject size Dave was using diffraction might well become more noticeable as the aperture gets smaller
Dave suggested using cheap extension tubes to get even larger macros of very small objects or to obviate the need for a dedicated macro lens. As I don’t work with such very small subjects I have never needed these on a DSLR or mirrorless camera. So I may be wrong but for any automated process, e.g. the built-in mirrorless app or Helicon Remote, I can only imagine you will need ones that have the correct, camera-specific, electrical contacts to allow the camera to control the lens focussing and, for some, aperture. These are usually advertised as being suitable for auto focus and are a little more expensive than the cheapest, basic, manual-only extension tubes. See link for some advantages and disadvantages of extension tubes, e.g. light loss which one can get over by turning up the flashguns or longer exposure times per frame.
Magic Lantern is a free application that runs on many Canon DSLRs. It is neither developed by nor supported by Canon. It adds a huge range of functions to the camera, including automated focus stacking, trap focus on movement and sound, interval timer, waveforms etc etc. Not all Canon models are supported and not all features work on all models. I have used it on my Canon 5DMkII and found some helpful new functions. I tended to keep one CF memory card with the Magic Lantern installed on it and used that card when I needed this software. It does come with some scary caveats that it could break your camera but it is used by many thousands of photographers and I don’t believe anyone has proven any hardware failure from using the app.
An excellent and very inspirational demonstration of focus stacking from Dave Smith.
I also enjoyed his light painting demo. It would be interesting to see light painting demonstrated using cameras that don’t have that helpful Olympus mode of building up a live image from multiple exposures. Dave suggested that instead of creating one single image of multiple lights one can have greater versatility by taking multiple frames and blending them in Photoshop; it is worth some experimentation designing and adding light trails to an existing image.