Fix The Focus Stack Warning In Photo RAW
Focus stacking is a technique to get extreme depth of field in a scene. Multiple photos of varying focal depths are captured and the sharpest portions of each are blended together into a single frame. Photo RAW automates the process. Select a se of photos in Browse, fire up the Focus Stacking window, and the blending is done for you.
Photo RAW has an additional feature - the Depth Of Field slider. These allow you to fine tune the focal plane in the stacked image. These sliders depend on focus depth metadata from your original photos. Different camera models write focal depth information in different places in EXIF data. Sometimes, Photo RAW can’t find the information. And sometimes, it’s because earlier versions of Photo RAW didn’t know as much about a vendor’s metadata as it does now.
That’s exactly what happened with photos from my Sony cameras. The initial release of of Photo RAW 2019 didn’t know where to find focus depth information. The 2019.2 release fixed that.
The Focus Stack Warning
If Photo RAW cannot determine the focus depth from your original images, there is a warning icon in the Focus Stacking window. If present, the warning is just to the right of the Depth Of Field slider.
Does this warning mean you cannot do a focus stack? Not entirely.
You can ignore the warning if you want maximum depth of field. By default, the Depth Of Field points are at either end of the slider. You can reset their positions by clicking Max. If this is the type of stack you want, ignore the warning.
But Scott… I want to fine tune the focus plane. What can I do? There is an option - refresh the metadata.
Re-Read Metadata And Refresh Focus Depth Info
Photo RAW scans photos when images or folders of images are first opened. As part of that process, Photo RAW reads various metadata from your photos and stores it in its internal database. Focus depth information is among the data read. However, Photo RAW won’t re-read metadata from photos it already knows about. Why? In most cases, it would be a waste of time and slow down workflow.
However, with each Photo RAW update, it learns more and more about RAW formats. Specifically for focus stacking, a new update may mean Photo RAW now knows how to pull out the focus depth information for your images. So we tell Browse to re-read the metadata.
Select the photos you are going to focus stack and choose Photo > Read Metadata from Photo. The metadata information in the Photo RAW database is updated for the selected photos.
Try The Focus Stack Again
With the metadata refreshed, try your focus stack again. Select the photos in Browse and open the Focus Stacking window. In the case of my Sony A7Rii, the warning icon is gone. Also notice focus depth information is above each of the individual frames in the Focus Stacking window.
When I see focus depth information, I know I can adjust the Depth Of Field slider and adjust the focal plane reliably.
Again… if you are doing a maximum depth of field focus stack (the Max button), you can safely ignore the warning icon in the Focus Stacking window. Otherwise, try re-reading metadata for the affected images. It might just do the trick!
