Haven't cleaned my C14 corrector for 4 years. It is getting a little dirty now but I reckon I could stretch another 2 years out of it. Mark you don't need to clean the glass if you have owned the scope for under 4 years. The dust and crud you see on the glass is not actually deminishing the image quality at all. The fluid from Bintel is good, but don't be in a rush to get it clean. It just will not make any difference. Only clean the glass when it is absolutely filthy or a bird or bat has dropped its business on it.
