Nothing like a fogged up scope when you've got deer in front of you, is there? I'd opt for open sights too, if my eyes were still good enough.
I can see a golf ball on the green 250 yards away, but have to have reading glasses to see this computer screen.
This is a true story and it happened around 83 or 84.
I went to Vancouver Island to go hunting with my cousin.
We hunted hard all day, but it was sleeting and raining and windy so we quit hunting about 2 hours before we would normally do so.
Driving down a logging road out pops this big (for the area) buck, Rocki slams on the brakes. I jump out, throw the clip into my gun and throw it up to my shoulder. This buck is 25 maybe 30 yards away, broadside and not moving. My scope is completely fogged, I say Rocki my scopes fogged I can't see it, Rocki hops out (the buck still hasn't moved) throws his gun up (while he is doing this I am flipping my scope over to use the sights). I've got the deer in my sights to back up Rocki's shot.
I hear "CLICK" then f*&^, I look over at Rocki, he looks at me, the deer is still standing there. We both start to laugh and un-load the rifles and watch the deer walk away.
Rocki was shooting factory bullets, and the one he chambered was a dud, it was the only time that rifle ever mis-fired on him.
We both figured that after that the buck deserved to walk away.