Tom alluded to it, and I'm sure he thought that it followed naturally, but I'll be more explicit:
When he says the "blades get sticky", he means they won't stop down when you shoot. In other words, your lens becomes, in effect, an aperture-less lens. It only shoots at the widest aperture, even though your body ~thinks~ the lens is being stopped down. So, you tend to get a lot of ove-exposed shots.
And, as Tom also points out, the oil will vapourize, eventually coating the optics with a fine mist.
cheers, frank
"The optimist thinks this is the best of all possible worlds. The pessimist fears it is true." -J. Robert Oppenheimer
From: graywolf <[EMAIL PROTECTED]> Reply-To: [EMAIL PROTECTED] To: [EMAIL PROTECTED] Subject: Re: Oily Blades Date: Sat, 07 Feb 2004 23:16:48 -0500
Actually it is grease. What happens is sometimes a lens gets hot (perhaps left in a hot car a lot), and the grease from the focusing helical migrates to the aperture blades sometimes making them sticky. When the happens they is usually a film of grease on the glass too, which does nothing for the image quality. The fix is a complete tear down, cleaning, and relubrication often costing more than you paid for the lens. If it happens to be a cheap zoom, you might as well toss it in the trash.
--
Ian bromehead wrote:What is the reason many lens adverts say oil-free aperture blades ? How do they become oily ? Its seems this is selling point when oil-free, but I don't profess to have the experience to know why its important Thanks Ian
-- graywolf http://graywolfphoto.com
"You might as well accept people as they are, you are not going to be able to change them anyway."
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