Practical limit on Resolution (Diffraction Grating)

[bphysics]

Homework Statement

In order to increase resolution of the diffraction gratings we can use them in higher orders of diffraction. What is the practical limit on using very high orders of diffraction?

Homework Equations

R = $$\lambda$$ / $$\Delta\lambda$$ = Nm

The Attempt at a Solution

I understand how to calculate the resolution via the above equation, but I'm not sure I understand where to draw the line for a practical limit

 

[NobodySpecial]

How does order effect the angle the light comes off the grating at?