Dust behind front element

[tims]

I'm interested in a used Orion 72mm scope for sale and queried the seller about the condition of the optics. He responded "Fine optics but a little dust behind the front element."
Just wondered: How does the dust get there (during assembly?) and will it degrade viewing?

Thanks

[AlexN]

Its very unlikely that you will ever notice a few spots of dust...

usually it gets in there when you're changing EP's or camera setups etc... Sometimes you can get it out with a can of oil free compressed air.. but I personally don't think that its worth the risks..

The dust will not be noticed during viewing unless its really really bad... I would recommend getting some photos...