Focus Stacking – Watch Photography Close Up
Focus stacking is a close up photography technique that is usually associated with photographing insects. However, it also has other applications for other types of macro photography. If you want to get a really close up view of a product such as a watch then you may find that you struggle to get it sharp all the way across the product. The closer you go, the smaller the depth of field becomes. So, although from a distance an aperture of f/8 might normally be more than enough to get everything sharp, this doesn’t apply when you get really close with a macro lens.
The image below shows a single shot taken at f/8 with the focus on the near side of the watch.
As you can see, only a small amount of the watch is actually in focus. Most of it is blurred as if we were using a wide aperture. One way of getting round this is to use an even smaller aperture to increase the depth of field (amount in focus). For example, you could shoot at f/18 or even beyond. However, in many instances this still isn’t enough to give you a fully sharp subject. You can also find that with tiny apertures you can lose a little of the best sharpness due to diffraction. So, even the bits showing up in focus may be slightly softer than you’d want.
The solution to this problem is to use focus stacking. This means shooting a series of images of your subject, each focussing on a different part of it. That way, you end up with a set of images that when put together will allow the whole subject to be sharp. So, you set up your first shot with the focus on one side of the subject (e.g. closest to you). Then you gradually change the focus by small amounts for each shot until you reach the other side. In this example I shot a series of 11 frames to get the fully sharp image at the top of the page after editing. Here are a couple of the shots taken at various stages.
Each of the images gave a different slice of the subject in focus. There are several important things to remember when shooting images for focus stacking. Firstly, make sure that you are shooting with the same settings, including your lighting. You don’t want the exposure to vary or the final image will look odd as it will have stripes that are brighter/darker. Secondly, make sure that your camera is as still as possible. You should use a tripod and ideally a cable or remote shutter release to ensure that the camera doesn’t move at all between shots. Thirdly, take more shots than you think you will need. It is important that you only make tiny adjustments to the focus each time or you may find that you have blurry patches when you come to put them together. Manual focus using live view to zoom in is most reliable for this.
Here is the lighting setup that I used for these shots:
It is a very simple lighting setup using just 1 speedlight mounted on a light stand. It was fired through a diffuser (the inside bit of a reflector) at an angle to soften the light and give an interesting lighting pattern. The camera was set up on a tripod with a flash trigger to set off the speedlight. The watch was on a piece of black Perspex. It was cleaned carefully beforehand as any dust or imperfections will be magnified by this type of close up photography.
Once you have your series of images covering the whole subject you can begin to edit them. I normally start in Lightroom and do a few basic tweaks. The easiest thing to do is to edit 1 image and then use the synchronise settings function to copy the same adjustments to all the frames. Then, select all the photos you are using, right click and choose Edit in Photoshop – Open as Layers in Photoshop. This will bring your files into one single Photoshop document. They will be layered on top of one another.
The next step is the easy bit. Photoshop does all the hard work for you here. Select all of the layers (click on the top one and then hold shift and click on the bottom one). Then choose Edit – Auto-Align Layers – Auto. This will ensure that any movement between frames is adjusted for. Photoshop will automatically align the layers for you. Then choose Edit – Auto-Blend Layers – Stack Images. This runs Photoshop’s automatic focus stacking feature. Once it has finished you should have your subject in full focus. Combine the layers (e.g. flatten the image or use Ctrl-Alt-Shift-E (Cmd-Opt-Shft-E on Mac) to create one combined layer). Then you can carry on editing your image (e.g. retouching any blemishes, sharpening, etc).
If your image doesn’t come out right after performing focus stacking in Photoshop then you probably didn’t have a sufficient set of images for it to work with. Either you missed a bit with your shifting focus or you may have moved the camera or settings. The closer you are to your subject, the narrower the depth of field becomes. So, you will need more and more images to get a good result. I tend to shoot around f/8 for each shot as it gives great image quality.
So, if you are interested in photographing very small subjects then focus stacking might be for you. Here is a quick checklist to summarise what we’ve looked at:
- Keep your camera still for every shot
- Keep your settings the same
- Use manual focus
- Make tiny changes to focus for each shot – use live view and zoom in to help
- Take more slices than you think you’ll need to ensure everything will be sharp
- Synchronise any processing across all the source photos
- Open files as layers in Photoshop
- Select all layers then Edit-Auto-Align-Auto
- Perform focus stacking – Edit-Auto-Blend-Stack
© Joe Lenton, May 2017