With a binocular, 8x is pretty much 8x from one model to another. Oh sure, the expensive 8x will still be sharper brighter and better, but these days, even an inexpensive 8x will do 90% of the work the high-priced model will do.
Not so with spotting scopes. As magnification goes up, the stakes get much higher. At 20x, most spotting scopes look reasonably good, but when you get past 30x, the pack begins to thin out rapidly.
For applications that entail seeing small detail at great distances, the highest magnification is in order. If you want an image that is as sharp at 60x as it as 20x, get out the checkbook. Your choices are limited and not cheap.
It breaks my heart to have to tell some customers that the $300 spotting scope they want just isn't up to the task of seeing tiny objects at extreme ranges. Heck, $300 buys you a good binocular, so why not a good spotting scope?
Sometimes I give the technical answer, but often were both disappointed when I tell them what they will have to spend to get the performance they expect and want. I often lose a sale and the customer gets depressed. Sometimes I get so upset that I want to lend them my Nikon.
Okay, well almost.