I see that inshaala turned the question around,

test it ... take a shot with your nikon of a similar subject

Right!!!

Here is the process I'll use ...

[1] If I'm going to get a group portrait of 10 people ... that would be 10 by 2 ft. for each person plus a side margin of about 2 ft.  That's 24 ft total subject width. 

[2] Set 2 stakes 24 ft. apart.

[3] Position the camera at the center of the staked area and just far enough back from the line between those stakes to get both side stakes in the image frame. 

[4] Use as a subject something the size of a person's head/torso and enough detail ... e.g. a pillow with a busy print.  Set a target in the center ... and also at either the far left (or far right). 

[5] Capture image ... inspect to see if I actually got enough detail. 

Great!  Thanks inshaala for making me think it through. 

--
Martin