[toni-a]

my 24-105 is showing a weird behavior I can't explain, the pictures are sharp but hazy just like when you have water condensation on the lens after using it in snow.

I sent it to service, it came back with excellent pictures, after during my trip to dubai, I took this lens, inside the malls there temperature is set to  16 degrees outside it is 40 degrees, the pictures were hazy with all the lenses.

However after drying the problem resolved with all lenses but my 24-105, it is less severe but it persists.

What could have gone wrong ? could it be a camera bag issue, a problem with the lens sealing ? the coating ? I am clueless about it 

 

[chrismiller]

Condensation I would say. Lenses are not sealed to air and water vapor. I had this with a sigma years ago. I put it somewhere warm and pumped the zoom action for a while.

[davidmanze]

 Has the lens dried out now and does the problem remain?

[toni-a]

 Has the lens dried out now and does the problem remain?

yes it is remaining

not fully hazy as it was but I have white halos around highlights and white areas 

[Brightcolours]

As pointed out, condensation. You need to take care with such temperature and humidity changes, allowing lenses to acclimatise in sealed plastic bags to the new temp. to avoid such issues. The lens being weather sealed does not mean it does not have air inside, of course it does and of course that air contains moisture. Like mentioned above, zoom the lens in and out  to circulate the air and indeed put it somewhere warm.