Bushnell torture (1 Viewer)

Went birding in my lunch hour yesterday and left my Bushnell Excursion 8x32s on the front seat of my car. Sunny afternoon (not really that warm) with the sun shining directly on one of the barrels. When I picked them up, ouch they were hot. The heated barrel failed to alter focus even though the other did. Deep depression. But no, wait, after an hour or so the focusing was back to normal. A lucky escape....or not. I wait to see if any long term damage has been done especially to the waterproofing or the nitrogen purge.

Moral of this tale- don't leave your binoculars exposed in your car on a sunny day.

I guess the real moral is never leave them where anyone else can see them. Otherwise you could be looking at damage to the car and theft of the binoculars.

That said, I hope there's no permanent damage.

DiP

Well rest assured it had nothing to do with the quality level of the binoculars in question. I had a similar experience with one particular pair of Zeiss FL 7x42s. Leaving them out in the sun...anywhere...caused the focus to stiffen up considerably. I have owned several pairs of that particular unit and this was the only one that ever did it.

That's the beauty of nitrogen.....doesn't expand or contract in temp extremes. Had the bino simply been sealed with air inside, when it got really hot, a seal could have been blown (which reminds me of a very good joke), due to pressure buildup. A word of advice....DON'T DO IT NO MORE!

Nitrogen (which is about 80% of air) expands (or in a fixed volume increases in pressure) like any other gas when it gets hot. All gases do. It was/is called Gay-Lussac's law.

http://en.wikipedia.org/wiki/Gay-Lussac's_Law

But I agree with the advice of not leaving them in a sealed car in the sun. The interior ambient temp will exceed 65C and in direct sun they will get hotter (that's hot enough to go ouch when you pick them up!).