Focus Stacking Images Taken in the Field?

Can you focus stack images taken in the field? Yes, even stacking just 2 or 3 images of varying focus distances can give you an improved view of a species that can be then displayed in a single image. The key is to not make it a priority over any key iNat objectives: namely, observe but don't disturb!

Focus stacking is improving the depth of field (area of your subject that is in focus) by digitally processing multiple exposures. A simple technique using the Adobe Lightroom/Photoshop suite is as follows:

Focus stacking of multiple images: In Lightroom, process the selected images in RAW or JPG, crop and align as closely as possible. With all images selected, right-click "Edit in" and choose "Open as Layers in Photoshop...". In Photoshop, highlight all layers and from Edit menu select "Auto-Align Layers" (default "Auto" for Projection) and click "OK". from Edit menu select "Auto Blend Layers...", choose "Stack Images" (default "Seamless Tones and Colors" and "Content Aware Fill Transparent Areas" checkboxes selected). Depending on the memory and processing power of your computer, be patient. Stacks with a dozen images may take several minutes. Save where appropriate.

Now in practical terms, each image you stack should overlap in focus a little to the next image to be stacked. Secondly there can be no movement of the species under observation, or the surface that the species is resting upon. If one image has a moved leg or antenna, you might end up with the software discerning that as an extra appendage! Now you can do some editing to obscure the unwanted appendage pre or post focus-stacking... but a word of advice: an altered image is probably not a good candidate for an observation on iNat since you may inadvertently alter a key characteristic or feature of the species (in regards to season, age, sex, etc).

REF: https://flic.kr/p/2iT3c5S (2 iamges stacked)
REF: https://flic.kr/p/2iTCrY1 (4 images stacked)
REF: https://flic.kr/p/2js4aTD (9 images stacked)
REF: https://flic.kr/s/aHsmMZkFA9 (album of stacked images)

A project on iNat for observations that include focus stacked images: https://www.inaturalist.org/projects/focus-stacked-images

Posted on May 12, 2022 05:44 PM by thumbwave thumbwave

Comments

Hi Craig: Saw your post about stacking - I do this extensively in the field for plants that don't blow in the wind... like succulents. Makes a huge difference to have better depth of field. I also shad plants to minimize harsh shadows. Using Olympus EM1 cameras with automated image stacking built in makes things a lot easier - though I still keep all the original images and stack later in Helicon Focus. For insects I haven't had much success - they either move or move in the wind or getting a tripod up to them is too difficult and time consuming. Even with stationary subjects like succulents, ants can sometimes move across the scene in the 1-2 sec it takes to make 10 or more images. (I usually take about 16-24 images, but the Olympus could do up to 999!)

In general, the closer you get the more valuable stacking becomes. I don't post much on inaturalist but my wife (argonauta) posts much of my photos.

Posted by douglasnoaa 14 days ago

Thank you for commenting Mike! Glad you have both made a good share of your travels. Yes, Rosario is quite prolific on iNat!

Posted by thumbwave 12 days ago

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