Buying a lensWhat do you check for

[dkhaw]

Hello Members
I was chatting with a pro last week and he told me some horror stories of his Canon lenses fogging up.

Can anyone let us have an idea how a lens could "fog-up"? Is this caused by the repeat in & outs of the lens from a very cold to warm temperature such as air-conditioned indoors out into the hot, humid outdoors? How do we prevent this phenomena from happening on our lenses?

Thanks & kind rgds
Daniel

 

[0000]

Daniel,

You must allow GRADUAL acclimatization. Let your gear warm or cool down SLOWLY.

You do this by putting the gear in a zip lock freezer bag.

Squeeze out most of the air. Not all of it.

Then go out into the warm humidity. After 30 minutes.

The gear should be equalized. Take it out. Shoot.

Seperate bags for bodies and lenses for larger than M stuff.

It works because you gradual take the air you trapped in the bag

from the one enviroment and warm it up SLOWLY.

The reverse is needed if you go from extreme cold to warm

As was the case during my time in Moscow inthe winter.

Simply bag the gear after being outside for a long time and let is warm up inside for a while and them take it out.

Just Bag it!

 

[dkhaw]

Thanks David - I thought this thread was long forgotten! I do use a similar method as yours and it does work.

What I meant about fogging of the lens is a permanent fog-like coating inside the lens which damages the lens forever. My theory is this: Is it caused by the condensation of moisture inside the barrel through transferring the lens in & out of different ambient temperatures too often allowing condensation of moisture to take place? The condensation could be acidic, etc caused by air pollution and it attacks the lens surface leaving behind a permanent coat.

Daniel

 

[wang]

Another possibility is the debris left behind by the opening and closing action of the aperture blades.