I am posting this in the equipment forum rather than the ep forum because it may get more, a broader exposure to more eyepiece experts knowledge, so here goes ! A few of the big names in eyepiece manufacture and sales offer some pretty expensive eps that have been purged with some sort of gas at quite a premium as a water / moisture proofing but not sure why as they aren’t being used out in rainy conditions where they will be saturated with H2O like say sonar systems, used for fishing or subsurface exploration, where weather conditions aren’t a controlling factor. Can the astronomers that have, I assume, studied their benefits, the pros and cons if you will prior to purchase, explain to me and I am sure others what type of seals including the material type that has been developed to maintain the seal in order to eliminate / prevent the sealed gas from escaping ? After all these eps are subjected to some pretty drastic temperature variants which as we all know cause a fair amount of expansion / contraction in these working seals, they have to insure the loss of gas for which you have paid a lot more when you buy the ep. And as well if a seal does let go what are the indicators that it has happened and what then, do you send it back and someone installs a new seal(s) and re-purges ? In marine electronics the screen starts to fog up drastically as the main indicator of the loss of Nitrogen when the heat of the day builds up in the unit but I have never heard of eps regularly fogging up except maybe in high humidity or heavy icy frost where most probably won’t be out observing anyway / very often ! What type and length of warranty do the sellers give the purging or should I say the loss of purging, if in fact it can be detected, is it a lifetime guarantee ? I mean there has to be an answer after all owners, the purchasers have paid for it ! Is it possible many are using these premiums and the gas has long escaped and no one even knows it ? Before I buy them, the thoughts are there, some things have to be answered ! Clear Skies and heres hoping for some great replies to help myself and other potential buyers understand ! PS: I know its been a problem in some of the big brand names in marine sonar equipment for at least 25-30 years, I mean I have been involved with that problem for that long !
Edited by LDW47, 21 February 2020 - 01:11 PM.