Started this as a cheap way to get fast glass. Ended up with a small box of metal cylinders, a working knowledge of Russian aperture rings, and opinions.

Here’s what I learned paying for it.

Read the seller’s photos, not the seller’s words

“Clean glass” means nothing. Every listing says clean glass. What tells you something is the picture where the seller shines a light through the lens from the back. If they didn’t take that picture, ask for it. If they won’t, move on. There are eleven thousand of these things for sale.

The Canon EOS R100 sits at the bottom of Canon’s RF lineup by price and by marketing priority. Canon treats it as an entry point — a camera for first-timers who will eventually buy something better. That framing misses what the R100 actually is: a compact APS-C body with a competent sensor, full RF mount compatibility, and a street price low enough that pairing it with serious glass remains financially rational. The crop factor works in its favor at the long end. The absence of in-body stabilization is a real constraint, not a dealbreaker.