North Carolina-class battleships carried two different types of rangefinder in their main battery turrets. The No. 1 turret used a coincidence rangefinder (single eyepiece), while turrets No. 2 and No. 3 used the larger stereoscopic rangefinders (two eyepieces). For technical details see 16F4. Rangefinders.
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Coincidence rangefinder in No. 1 turret only — note the single eyepiece. For more information see 16F4. Rangefinders.
Stereoscopic rangefinders in turrets No. 2 and No. 3 — note the two eyepieces. For more information see 16F4. Rangefinders.