Universal iris mount too expensive or too small? Try this!

Universal iris mounts are nice, if expensive items, if they don't come as part of a package purchase.

I used to be quite sceptical of their ability to hold heavier lenses (more than 500g) but they seem to reliable based on 3/4 years of field use, even if they don't always hold the lens absolutely rock steady. They are not particularly effective approaching maximum diameter, where the extra thickness of many iris blades don't fit threads very well.

I recently got hold of a Derogy-lensed anon. pill-box meniscus of some size (800g), without the flange. It has just too large a diameter for my largest universal iris clamp. I used the basic system - I have used to make "threaded" cut brass lens hoods and cell mount threads.

The "flange" was cut out of a recycled brass sheet (fingers and eyes!!) and soft solder directly to the flange. The lens cell was removed before this operation.

The rear of the flange doesn't look very splendid but this is not visable. The attachment is most achieved due to the soft solder being pushed down in the thread on the lens. It is certainly far more secure than a universal iris mount.

Removal is easy and the threads can be cleaned up afterwards (300 deg C?) without any damage.
Note that some lens construction may require that the flange is removable for easy removal of the the rear cell!

Thanks, Steven.... Do you use soft silver solder or low lead? Bill

Ordinary high lead soft solder/resin from the local hardwear store for electrical work!
This is not my best soldering work!

Mass production flanges are over dimensioned as they have to rigid in the lathe.

Really good idea!

And thanks for the Universal Iris info, I think I can live without one. Maybe...

Plenty of sheet brass left. This is the old wood floor fire protection in front of a woodstove.

To-day it was flange for a 30" Wray meniscus. Not cleaned up yet.

The "flange" needs quite a few "spot solders" as the brass changes dimensions under heating.