ILC with IBIS and Weather Sealing?

Started 2 months ago | Questions thread
bobn2 Forum Pro • Posts: 63,854
Re: ILC with IBIS and Weather Sealing?

Barmaglot_07 wrote:

bobn2 wrote:

It makes it non-waterproof. It will only be a hermetic seal if it was designed to have a hermetic seal in the first place.

You have some weird definition of sealing, by which any seal that isn't permanent is not a seal at all.

The question is not about the word 'sealing', it is about the word 'hermetic'. 'Hermetic' sealing is sealed against entry or exit of air or gas. That is very different from being sealed against water, because water (a liquid) and gases have very different physical properties. It's quite possible (and if fact common) to make something that is sealed to water but not sealed to gases. Hermetically sealed items generally have inside a controlled atmosphere because once something such as water vapour (a gas) gets in, it can't get out and therefore will do damage within the seal. It would be very bad design practice to make a water sealed ILC hermetically sealed, because it would inevitably get water vapour inside when lenses were changed and once in it would never get out. Such items will generally be made with somewhere inside a gas vent (made, for instance by Gore) which seals against water but will let gases pass both ways. Since they have gas vents they are not hermetically sealed.

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...because you know, sometimes words have two meanings.

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