No flange? How to attach brass lenses to lens boards - A simple solution

It's rather frustrating but not surprising that many brass lenses have become separated from their flanges over the years. It's also a pain that many early lens thread weren't standard. However there are several solutions to this problem.

• Get a bespoke flange made - very expensive.

• Find a used flange. Can be expensive and threads aren't standard, an element of luck is needed!

• Use an iris mount - expensive. Lenses are limited to the diameter of the iris mount.

• Cut a hole slightly smaller than the thread and screw the lens in - maybe ok with a lightweight dinky cheap lenses but not with my large Petzvals!

• Glue the lens in - Cheap. Not as crazy as you may think. I've done this before by putting 4 tiny dabs of glue on the back of the lensboard where the lens pokes through. It's quite easy to remove the lens as the epoxy glue shatters off. I'd only do this with a lightweight lens though.

The following method works well even for fairly heavy lenses. It ridiculously cheap, maybe £2 or £3, very easy to make - you just need a hacksaw, file and drill.

Mark four pieces of 3mm thick aluminium by drawing around the lens mount to get a close matching curve. I’ve used aluminium 45mm x 25mm here for my 12" Darlot cone which is quite heavy.

File out the curve shape. This is really easy to do with aluminium as it's so soft. Now cut four more pieces of 3mm thick aluminium, smaller in width but the same length. I’ve use 15mm wide aluminium. With two part epoxy glue the two parts together.

Drill mounting holes to attach to the lensboard. Attach some felt and trim to size. Make sure you leave an overlap of a few mm, this will fold up when you attach to lens preventing scratches. Attach using nuts and bolts rather than screws.

That's it! Not pretty but does the job.