What magnification would be necessary in a spotting scope for hunting in Alaska? Also what magnification scope would be good for sheep and/or goat hunting?
Magnification can be both friend and foe. What's most important is how well the scope/eyepiece combo resolves detail. A cheap scope at 60 power is much worse than a high quality scope at 30 power. Sometimes 20x is all you can use depending on conditions. Also, useful magnification is related to the objective lens size. As a general rule a 65mm scope is maxed out at about 45-50x. An 85mm scope- 60x and a 100mm scope 70. After those mags the image resolution begins to degrade. Obviously there is a little room one way or the other but, I think you get the idea. Alos, the higher the mag, the larger the objective lens should be to allow more light in order to resolve more detail. Remember, with sheep we are wanting to be able to see lamb tips or broomed horns. A small, high resolution image is better than a larger, low res image. High mag only makes the image larger, and that, at the cost of resolution unless you have a high quality scope. Which is what you want.
Remember also that as you turn up the magnification you also magnify the atmosphere which causes distortion as well.
For a mountain hunting scope the 17-50x65mm (or so) scopes are about the norm and a good choice. But, Swaro has a 20-60x65mm scope.
If you are going with a fixed power scope 30x should be about max. I've used fixed power but prefer the flexibility of a zoom. Even though, all else being equal, a fixed power eyepiece will give a better image. But, for hunting it's not an issue.
Figure out how much you are willing to spend, then go look through some 65mm scopes. Unless you are willing to carry a heavier, bulkier scope like the Zeiss 20-60x85mm. Some guys are, some guys aren't.