Focus Stacking For Tiny Subjects

Focus stacking is a photographic technique in which multiple exposures are taken of a subject, with the focus distance set to different lengths. These images are then composited together to create a final image with a greater depth of field than is possible with a single exposure. [Peter Lin] built a rig for accurate focus stacking with very small subjects.

The heart of the rig is a motion platform consisting of a tiny stepper motor fitted with a linear slide screw. This is connected to an Arduino or PIC with a basic stepper driver board. While the motor does not respond well to microstepping or other advanced techniques, simply driving it properly can give a resolution of 15 μm per step.

The motor/slide combination is not particularly powerful, and thus cannot readily be used to move the camera or optics. Instead, the rig is designed for photography of very small objects, in which the rail will move the subject itself.

It’s a tidy build that would serve well for anyone regularly doing macro focus stack photography. If you’ve been trying to better photograph your insect collection, this one is for you. It’s a valuable technique and one that applies to microscopy too. Video after the break.

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Impossibly Huge Depth Of Focus In Microscope Photographs

Sometimes, less is more. Sometimes, more is more. There is a type of person who believes that if enough photos of the same subject are taken, one of them will shine above the rest as a gleaming example of what is possible with a phone camera and a steady hand. Other people know how to frame a picture before hitting the shutter button. In some cases, the best method may be snapping a handful of photos to get one good one, not by chance, but by design.

[The Thought Emporium]’s video, also below the break, is about getting crisp pictures from a DSLR camera and a microscope using focus stacking, sometimes called image stacking. The premise is to take a series of photos that each have a different part of the subject in focus. In a microscope, this range will be microscopic but in a park, that could be several meters. When the images are combined, he uses Adobe products, the areas in focus are saved while the out-of-focus areas are discarded and the result is a single photo with an impossible depth of focus. We can’t help but remember those light-field cameras which didn’t rely on moving lenses to focus but took many photos, each at a different focal range.

[The Thought Emporium] has shown us his photography passion before, as well as his affinity for taking the cells out of plants and unusual cuts from the butcher and even taking a noble stab at beating lactose intolerance.

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DSLR Focus Stacking Assistant Takes The Hard Work Out Of Macro Photography

canon_dslr_focus_stacking_assistant

Focus stacking makes for fantastic macro images, but the process can be tedious without the right tools. While some focus stacking rigs require the camera to be moved away from the subject in small increments, others choose to keep the camera stationary while focusing the lens before each shot.

Both methods produce great results, but you need a steady hand and a lot of patience to get the job done. [Oleg] uses the focus stacking technique relatively frequently, so he decided to automate the process in order to save himself some time. Using an Arduino and a USB host shield from Adafruit, he put together a focus stacking assistant for his Canon EOS camera.

The assistant allows him to set two focal points, leaving the Arduino and his camera with the task of taking pictures. The Arduino commands the camera to tweak the focal point ever so slightly between each image, resulting in an array of images ready for stacking.

He says that the process is a bit slow at the moment, but he’ll be cleaning up the code and building a Nikon-compatible unit in the weeks to come.