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Photo Tips - Focus Stacking

As we know (or should know) the smaller the aperture you use the greater the depth of field will be, or the amount that will be in focus in your photograph. There are limitations to this of course and it becomes particularly noticeable with macro or close up photography where getting enough of your subject in focus is notoriously difficult. Sure, one’s immediate reaction to this is to simply reduce the size of the aperture, heading towards f16 or f22. This will certainly increase what’s in focus but diffraction rears its ugly head - as the aperture gets smaller you will have more in focus but the image will become softer and softer. Not only that, the background bokeh in the images will also be sharper, destroying any subject isolation that you were hoping to create.

One solution to this is to shoot a series of images at say f5,6 or f8 where the in focus areas are fabulously sharp, each at a slightly different point of focus, and then combine them, using only the sharpest parts of each image. Just like in HDR image merging, it’s possible to do this manually, but it is way easier to automate this in photoshop or one of the other image stacking apps that are available.

Photographed at Sanbona Wildlife Reserve near  Barrydale, this photo just does not have enough depth of field to get both flowers of the brakveldwitvygie in focus, despite being shot at f11.

Photographed at Sanbona Wildlife Reserve near Barrydale, this photo just does not have enough depth of field to get both flowers of the brakveldwitvygie in focus, despite being shot at f11.

This is a case where you want to lock down your exposure, so setting your camera to manual is the way to go. Then shoot a series of images of your subject from front to back, adjusting your point of focus as you go. This, in many cases will need to be done manually unless your camera, like the Panasonic G9 and GH5 cameras that we use, has what they call focus bracketing that does it automatically. For the pic of the flower below, we found that shooting 10 images was sufficient but you may need more or less depending on the size of the subject and the aperture you have chosen.

Needless to say, like with HDR images, you’ll once again need a static subject and the camera on a tripod. Once you have taken all your pics, then edit them, getting your levels, contrast, vibrance, and colour corrections sorted. Make sure that you do the same to all the pics. In Lightroom this is easy, edit one pic and then sync the edits with all the images in the series. Open the series as layers in Photoshop (In Lightroom, right-click the selected series and go to Edit In) - Open as Layers in Photoshop. Make sure that all the layers are selected in the Layers Panel and then go to Edit - Auto Align Layers, selecting Auto in the dialog box. Photoshop aligns the images, compensating for any slight movements that may have occurred. Then go to Edit - Auto Blend Layers. Make sure that you select Stack Images and that Seamless Tones and Colors are selected. Click OK. Work happens in the background…

This is a combination of 15 different photographs each shot at a slightly different focus point, resulting in both flowers being in focus with the background still suitably soft.

This is a combination of 15 different photographs each shot at a slightly different focus point, resulting in both flowers being in focus with the background still suitably soft.

In a short while you should have your final image. You may need to crop it slightly to compensate for the Auto Align operation and then make your final tweaks and adjustments.

Be sure to check out our other Photo Tips and tutorials and watch our video tutorials.

As always, if you have any questions or suggestions for future articles, do drop me a mail. Hook up with us on Instagram (@RogerdelaHarpe) and Facebook ( Roger and Pat de la Harpe Photography).

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