Looking for ideas for mounting threads onto PT-EP10

[Ryan B.]

I have an Olympus PT-EP10 underwater camera housing with a glass front port to which I'd like to be able to screw-in and remove a 67mm threaded INON underwater macro diopter.
The diameter of the front exterior glass port is 90mm and the lens barrel inside the port is 70mm.
Ideally, I'd like to find a thin 90mm diameter metal or durable plastic ring with inner threads of either 82, 77, 74, or 72mm--as all these diameters are wider than 70mm, and are easily acquirable sizes for step-down rings. (e.g. 77mm to 67mm step-down rings.)
Unfortunately the plastic rim around the front of the glass port is unthreaded (what was they thinking?) and (except for one thin mm) angled and, knowing no other clever way to attach it, the ring will have to be made of a material that can handle salt water and easily bonds to, but does not fog, glass.
Any ideas how to acquire such a ring, or any alternative suggestions?



Thanks, I appreciate your consideration,

 

[MB NZ]

Yes, saw a neat job on a dive boat recently. The lens cap had a large appropriately sized hole drilled in it and a wet diopter was fixed on to it. Not sure how it was fixed, but it's a start!

 

[KeithG]

have you considered a moveable design instead?

my old housing used a reefnet flip up holder to position the diopter infront of the lens. my new housing has a 67mm thread. the flipup is infinitely easier to "switch" lens.

i have also seen holders that rotate the lens in front of the port.

a moveable holder is likely harder to build, but i am going that route for my next dive trip.

for a screw on, your local camera supply may have some step up/down rings but several of these may likely cost more than buying a commercial mount?

i would not try affixing anything to the port lens but would happily glue to the housing. alternatively you could use some of the port front plate screws and attach mounting points via these - 3 longer screws should do the trick.

 

[Ryan B.]

Good ideas all! Thank you, gentlemen.

 

[Ryan B.]

I've come to 1 1/2 solutions. In the one, I took Andrew Rawlingson's suggestion above and drilled a hole through my lens cap. (A 2 1/2" hole saw was the largest I could find, so I widened it with an exacto blade, then sanded.) I put an 82-67mm step-down ring inside the cap (I had to trim a couple lines of plastic so it wouldn't sit too proud and touch the glass), strapped a faucet o-ring around the Inon lens to keep it sliding in too far, then screwed the Inon diopter through the outside of the lens cap and into step-down ring. For grins, I added another step-down ring, 67-58mm, so I could layer an old Hydrophoto diopter on top of that. Easy to put on and off underwater, and is a great improvement to the 14-42mm lens' macro ability, but it is a bit bulky.
For the 1/2 solution, I took a blue 80x90x6mm urethane cylinder wiper ring, $6 on ebay, squeezed an 82-77mm (wider than the 70mm interior barrel of the lens port) step-down ring into it--boiling it to help seal them together--then added another 77-67mm step-down ring for mounting the Inon diopter. This should be the third picture below.
I'm not sure,however, how to affix it to the front of the port without adhesive--which would make the port difficult to repair at some hypothetical time in the future, and also creates hidden niches for salt to build up. I like giffenk's suggestion of using the port front plate screws to attach mounting points, or clamps, but no good ideas yet about what to use for those clamps. Any ideas?

 

[lucca brassi]

If I would on your place , I would took down red ring from housing and replace it with costum ring which would do function you want .

You can do that from delrin piece or aluminium which you need to anodize for protection and you have clean solution .

At CPF machining forum you have experienced people that can do that turning and cuting threads in material

CandlePowerForums

 

[Ryan B.]

Thanks, Lucca (I get it, "Lucca Brassi sleeps with the fishes"). Sounds a bit beyond my limited wallet, though.

 

[EskilJ]

Hi Ryan
I bought the expensive olympus thing for it: PMLA-EP01. It is like the lens cap, with a hole in it and a threading inside. The standard clip-on holders hold it- like on the lens cap, but I think it's from ticker plastic, so the "click-holders" hold better.
Maybe you can improve the action of the existing click-holders on your dust-cap?

 

[Divealpha]

Bought a cheap flip adapter from Bubblescuba on Ebay. ..much better solution, .....