Objectives highlighted in yellow are the ones currently installed on the Nexview 3D turret.
The Nexview 3D has 4 objectives on the turret and 3 internal magnifications, giving 12 FOV (highlighted in the middle of the above image), some of which overlap.
So, which do you choose?
Most often it is the size of what you are trying to measure which determines the FOV you want to work at.
But what about the overlapping fields of view; which objective should I use?
In the case of overlapping FOV; for example, the 10X objective can be used as a 5X, 10X, or 20X, and the 20X objective can be used as a 10X, 20X, or 40X. They both have 10X and 20X options; so, which do I choose? The 20X is the choice over the 10X on flatter samples as it has the better NA, which means you have better optical resolution. However, the 10X has a much further working distance and can be useful on rougher samples when we can't use the 20X.
These are the things you consider when making your objective choice.