If all mires are out of focus on a radioscope verification, what is likely true about the lens?

If all mires are out of focus during radioscope verification, it is likely that the lens is warped. A warped lens can cause light to refract improperly, which would lead to blurriness or distortion of the mires' images across the entire field of view. This distortion prevents the practitioner from aligning and calibrating the device accurately, as the intended clear focus provided by an undistorted lens is compromised.

In contrast, improper fitting may contribute to alignment issues but would not necessarily cause all mires to uniformly be out of focus; it might only affect certain areas. A lens that is too thick doesn't typically affect focus in this manner, but might influence other aspects like weight or light transmission. Lastly, if a lens has no power, it would generally cause the mires to appear flat or out of focus in a very predictable manner, but not all at once in a uniform way indicative of warping. Therefore, a warped lens presents the most coherent explanation for the lack of focus across all mires.