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Pentax 10x50 PCF WP binos - they're fogging up

biocysm
Posted 28/10/2002 - 18:33 Link
I bought a pair of Pentax 10x50 PCF WP binos a couple months ago and i finally put them to the test during my deer hunt. The temp didnt drop below 25 or 30 at any time. They fogged up every morning and so i had to put them over the defroster in my truck every morning. They fogged up every time it rained or snowed and so i was slipping them under my coat constantly for a little defrosting. I was told they were nitrogen-filled but now i'm starting to wonder. Is it possible that i bought some "special" international version that isnt fogproof or nitrogen-filled? I bought them from the SWFA Riflescopes website for $169 (http://www.swfariflescopes.com). Any help will help. Thanx.
Pete Bargh
Posted 29/10/2002 - 13:23 Link
According to our service contact at Pentax PCF WP binoculars will not fog on the inside elements due to there being nitrogen inside. When warm humid air meets a cold boundary condensation occurs. One of the benefits of filling binoculars with nitrogen is that moisture is removed thus preventing fogging of the internal elements.
However, the weak spot of any binocular with regard to fogging is the air glass boundary. When a cold pair of binoculars is introduced into a warmer humid environment then fogging may occur on the external surfaces including the lens elements.
One way of preventing this is to ensure that the lens elements are kept warmer than the surroundings. So just as your spectacles will not fog up when leaving a warm house neither will the binoculars.
One more thing to consider is that even though the binocular is nitrogen filled, and so will not fog internally, the label that states that the binocular is fog proof does not refer to fogging. It refers to the binocular not being damaged by moisture penetration caused by fog, or rain, or snow, or water.

However, despite all this explanation it is possible that the seals on the lens may be damaged thus allowing fogging to occur inside the lens. You could send them back to Pentax for assessment so they can check for faults and proceed accordingly.
Publisher
Magezine Publishing Ltd

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