Your lens and camera do not go from 75F to 0F immediately due to the thermal inertia of the lens components and because air, in itself, is not a very good thermal conductor.
Moreover, pro-lens manufacturers use materials that have a very low coefficients of expansion. If I were you I would not worry about sudden contractions or expansion, because they don’t happen and since they don’t happen and the very low coefficient of expansion of the different materials won’t lead to misalignment in pro-lenses. But if you wish you can let the low temperature settle to all components of the lens, which means waiting for a long while as they reduce their temperature to 0F, if you think you need critical accuracy.
But on the other hand, condensation inside the lenses could be a problem due to the electronic that most modern lenses have and fungus proliferation.
If the lens isn’t airtight, when you move it form a place where it has stayed for a long while that has warm temperature and a high absolute humidity to a place with a much lower temperature and lower absolute humidity, this will be the physic phenomena that'll occur:
- The air within the lens will still be the one it got before with
the same humidity.
- Its temperature will fall relatively fast (due to the low thermal
inertia of the air).
- The air trapped will get below its dew point and its humidity will
start to condensate (became liquid).
- You will end up with dew inside your lens.
But on the other hand your climate must already be very dry (relative and absolute humidity) during the cold season and I don’t think you are increasing the absolute humidity of your “house” by much. If you were increasing the absolute humidity by a lot, you should get a dehumidifier for your equipment closet to avoid the physical phenomena explained before.
A similar thing will happen when you go back inside from the freezing cold, if you have been outside for a while, the dew will occur on the outside of your equipment (notice the fogging of the glass in its outside). This is due to the fact that the low temperature of your equipment is lowering the temperature of the air surrounding it below its dew point. Inside the lens the outside air will raise its temperature but won’t generate any dew because it won’t become saturated.