When are Summer temperatures unsafe for lenses ?

[Sirius Glass]

Puh-leeze. Now we supposed to monitor lens temperatures? I've never had any other lense have the grease vaporize. There are synthetic greases that don't even start to sweat until the hundreds of degrees F.

Even synthetic greases vaporize in the heat that builds up in cars. And yes you have to monitor all photographic equipment in the heat especially the digital ones.