Focus Stacking and Stitching: Ralf Graebner and his 'Change' series using found-on-the-street NYC quarter-dollar coins
See my Nikon wish list.
I thought this a very interesting combination of stitching and stacking.
Ralf Graebner writes:
Snce you mention the technique of focus stacking more and more in your blog, I thought I’d introduce to you a photo series that I’ve been working on for 3 years now which wouldn’t be possible without focus stacking.
Over the years I picked up used/beaten up quarters from the streets of New York City. What fascinated me was the range of colors and textures these quarters had taken on being exposed to harsh environments over time, but also the thought that they had all started off looking identical at the time they were minted. I ended up calling this photo series “Change”.
My vision was to create very large, extremely detailed prints. After a lot of testing and creating versions of prints I now have a setup and workflow that gives me more than enough detail to create these 72“ x 72“ prints. Essentially I create a three-dimensionally stitched panorama of each of these coins. The lens I use is a microscopic objective with 6.5x magnification, so I photograph small sections of the surface of these quarters, 10 rows and 10 columns to capture the whole coin (with overlap for the stitching process).
But the true challenge is capturing the surface without loss of detail caused by diffraction. The microscopic objective I use has a working aperture of about 11 (at 6.5x magnification) but the resulting DOF is only about 1/100 mm, much less than the depth of the relief of the quarter. So, if I wanted to capture just 1 mm of DOF I’d have to create a focus stack of 100 shots for each of the 100 sections. But since you need overlap for the focus stacking process also, I move the camera in increments of 8/1000 mm. In case of the red 1984 quarter (which I am proud to say Alec Baldwin bought from me) each section ended up being a focus stack of 170 shots, or 14.500 exposures to capture the whole quarter.
I’ve tested both Zerene Stacker and Helicon Focus, and I do prefer Helicon Focus. But only an older version, 6.1, since newer versions have become dramatically slower, by a factor of 4! (Though, maybe that was a bug that has been fixed in the meantime) This may not have much of an impact with small stacks, but it does make a significant difference if I have to wait 5 minutes for a stack to be created, or 20 minutes.
I studied photography in Bielefeld, Germany, but I can say that your expertise and in-depth reporting also honed my knowledge about the technical side of photography considerably, so thank you for that Lloyd! Now that the Sony A7R III is out I will subscribe to your blog again very soon!
All the best!
DIGLLOYD: very cool project! See ralfgraebner.com for more.