Macro Port Protector

Hi All!

I plan to make the following macro port protector:

red ... port in aluminum

green ... glass of the port

white ... clamp on (by tight fit o-ring) port protector

blue ... clamp in lid

The white part should be installed "permanently" on the port, most likely with a tight fit o-ring or small set screws. The inner diameter hole should be big enough so that the view angle of the 60mm lens is not disturbed. The blue part would be to protect the the remaining little area, although this might not be necessary. I would add some small holes close to the outer circumfence to let water drain away after the dive.

The material would be black POM (Delrin).

My question: Will the small diameter hole in the white colored cover disturb the light for the lens as long as the viewangle is not disturbed? I would guess that I get less stray light into the lens, which is good. Any ideas of drawbacks?

Thanks for any feedback, Wolfgang

Can't think of many - your biggest issue is that you still want the lens to function with the aperture wide open - or goodbye autofocus and manual focus will be a tough call.

Think when you do the math on the angles the 'protection' will not be great if you want that F2.8 to focus with....

Paul C

P.S nice bit of Autocad though!

Paul C

Paul!

Thanks for your answer. What would you estimate to be the minimum diameter of the inner opening?

If the whole thing is "useless" in the end, I will just make the white thing as protection cap which is removed during the dive.

Problem is, that I will be diving in the Atlantic Ocean soon, partially diving from land. Wind and waves can be quite strong, so I want to protect my gear as good as possible (apart from the insurance). So during the dive I don't need the protection really.

Wolfgang

Easy to try - with the aperture wide (F2.8 / camera in auto focus) poke a bit of card over the port until you see it in the viewfinder - probably take a shot at the wide open position also - your viewfinder may well not see 100% of the frame.

You may also find that the lens is not 'exactly' centred in the port - not unusual - so don't cut it too fine.

FWIW I would go for a hard Delrin cover that you remove during the dive.

Paul C