Yes you are right, I don't know what I was thinking. I just bought them. So the second picture was with the dark slides removed?
Yes dark slides out in second photo.
With some fine steel wool you may be able to clean them all up. Touch them up with black enamel.
Then you will need inserts for the empty ones. Or pitch 'em if you don't like dealing with rust.
There is a lever at the top of the holder, that actuates a clamp. You will see how it works. In the early days of Plaubel Makina, 6.5cmx9cm glass plates would go directly into the holder. As modern sheet film came around, inserts came into play. You remove the insert, load it with sheet film, and reinsert it into the holder. Very straightforward.
I like using these holders. Just be careful to re-insert the dark slide -carefully- when shooting quickly, I have lost a few frames because the slide wasn't actually in the slot in the holder.
