Donald Qualls
Subscriber
Maybe because I used a plastic holder rather than wooden?
The film space is the same in the oldest "film only" wood holders and the most recently manufactured plastic ones. I think people who make this work in a double dark slide are taping the Instax print to the septum and then lightly forcing the dark slide into place over it. How they do the taping in the dark and get the print straight, I couldn't say... It might work better in a holder for glass plates, without the film sheath -- but then you'll have a focus offset.