Need for parallax adjustment for shooting out to 400 m

[canoetrpr]

I've been looking at the Zeiss conquest scopes and realized that the lower mag models 2-10x HD5 and 3-9x 40mm have parallax adjustment fixed at 100 yards.

3-15x HD5 is adjustable from 50 yards up.

Assuming that this is for a hunting situation for say Elk, that will never be over 400m, how important is it to have adjustable parallax? I'm guessing it is not and I probably don't want to be messing with the knob anyway.

I've concluded from another thread that the lower mag scopes will do me fine at that distance so that leaves the Parallax knob as a feature I'm trying to decide on.

 

[Bakersfield7.62]

They say that if the max power is 10x or less there is no need for parallax knob my 2c...
But on a shot at an elk at 400 yards rested in a less than ideal shooting position I would rather have the knob just to feel better about the shot

 

[dero338]

parallax error at a "X" distance and set at "Y" power depend on optic quality
example, my nikon monarch 2.5-10 has about a foot of parallax error at 400yards
but if your eye is carfuly aligned with the optic centerline, there is no problem to take the shot