To prevent any dampness internally on closed tubes assemblies get hold of an old plastic 35mm film canister, make several fine holes in the base, I used a hot needle held in pliers to do this. Remove the lid and part fill the canister with scilica gell. The canister will fit in place of a standard 1.25 inch eye piece bung.

The gell can be replaced from time to time or rejuvenated by spreading on a baking tray and putting in a warm oven for a while.

I've made several of these now, the problem is getting hold of the film canisters these days....anyone know where to get some from?

I have a couple of dozen 35mm film canisters if anyone wants some!

I'll have a few please.

Pete

Just an update on this, it may be better not to open the silica gell packets, just stuff a couple of small ones into the plastic container to prevent small particles entering the tube. Aparantly the stuff is very abrasive and you wouldn't want abrasives inside your optics!
That said I've not noticed the ones I made acting like salt shakers!


Pete