Wasout at my favourite firearms retailer the other day, and he has some US military Trigger Finger gloves - basically, these are a fully enclosed mitten, with the first finger and thumb having their own space to freely move (and fully covered. They are 10% wool/25% nylon, so durable and warm, and offer a modicum of water proofing.
I tried them out recently, and they are PERFECT for focusing, keyboard use etc, and warm.
At $3 a pair (one size fits all), hard to go wrong! If anyone wants some, I can order a batch of them.
Oh, one colour only - olive drab green

So, it may clash with your observing wardrobe, if'n you are that way inclined