"Try before you buy" is the mantra of binocular purchasing, but that goes double for Canon IS bin for reasons stated above, what is often called "swimming" images.
Some models have better stability than others and some samples have better stability than others.
Your best bet and most reasonably priced 10x is the 10x30 IS.
I had one, a good sample, and liked it very much. My only gripe was the smallish exit pupil - 3mm, which I found a bit dim compared to my 4-5mm exit pupil bins - on dark, overcast days in the fall and in the winter.
They are small, light, fit the hand nicely and if your dad doesn't have a problem with the "swimming" now and then, he should be well pleased.
The edge sharpness is also very good.
An annoyance that some people have found is that with the smaller models, you have to keep the button pressed with your finger while the larger models have a 5-minute delay.
I found that for my large hands, the button fell in a good position so it wasn't fatiguing.
You'll also need to purchase some lithium AA batteries for longer life.
They are not WP like the more expensive, bulkier, and heavier, but optically superior 10x42 IS L.
If you are buying these from a store, and they have more than one sample, compare them and see if there's one that has the least amount of "swimming".
Look at an object and then shake your hands a bit and see how the IS responds to the vibrations.
The sample that keeps the image steadiest is the one to buy.
If surprising your dad isn't important, take him with you and let him try the 10x30 IS.
What you experience through the IS bins, may not be what he does, though the "shake" experiment will help if you would rather surprise him with the present.
nly setback ,Close focus is about 25 ft with the 12s
