Rangefinder's Range of Effect

[HistoricalAccuracyMan]

Stereoscopic Rangefinders: "Improves Long Range Accuracy"

Coincidence Rangefinders: "Better aiming speed and improved base accuracy"

Historically, that is somewhat the case: stereoscopic rangefinders were superior for long range targets, while coincidence rangefinders were better for targets that were closer to you. What I want to know is, for the sake of choosing what rangefinders would work best for my ships, what is defined as "long range" when it comes to Stereo/Coinc Rangefinders? Meaning, does the Stereoscopic RF only improve accuracy beyond a certain distance that is considered to be the start of "long range," or is "long range" dependent on what caliber guns you have (long range for a 6" gun would be a chip-shot for a 16" gun)? I feel like this could really clarify some things because let's say that the Stereoscopic RF improves gun accuracy from 15km and out to the max range of your guns and say that it is the same value of 15km and outward for every gun. This could immediately tell you whether or not your ship is set up for hitting the enemy at range, or getting close and annihilating them. Plus, if it functions like that, you would know to not take a Stereoscopic RF if your guns can't go out to 15km, or can't shoot much farther than that.

Basically.....at what distance does "long range" start to mean something or is "long range" dependent on your gun size (in which case, what is considered "long range" for every gun size or is there some sort of formula/equation I can follow to figure it out)?

[disc]

23 hours ago, HistoricalAccuracyMan said:

Historically, that is somewhat the case: stereoscopic rangefinders were superior for long range targets, while coincidence rangefinders were better for targets that were closer to you.

There are differences between rangefinder accuracy characteristics -- mainly relating to target shape and operator proficiency --but I have never heard of this before. What is your source?

[Hangar18]

I have no idea, it really bothers me. just swap between them and look at the gun accuracy changes

[HistoricalAccuracyMan]

I've watched a couple documentaries over Naval Combat and Navy Tech, as well as read a few articles over the subject--I also believe Drachnifiel on YouTube has a video over rangefinders. You are right when it comes to target shape and operator proficiency--those affect the accuracy too--but a handful of those documentaries and articles talked about how, sometimes, the stereoscopic rangefinders were used for long range gunnery more that the coincidence rangefinders were because the stereoscopics were usually wider/longer (however you want to look at it) thus resulting in better accuracy and the coincidence rangefinders were generally used for secondary armaments, since their range was a lot shorter than that of the main battery.

[akd]

There is really no justification.  Just a fake choice to provide more choices, but ends up undermining the tactical impact of the actual technology.  The more meaningful decision was how long of a base to use and where to mount it, not coincidence vs. stereoscopic.

Quote

Which rangefinder system is superior remains a matter of controversy to this day. The Germans immediately adopted the stereoscopic rangefinder, while the British and most other navies went with the coincidence system. The biggest advantage of the stereoscopic system is that it allows ranging on objects without a strong vertical element, such as shell splashes and airplanes. It was also generally considered more sensitive in bad lighting and areas of low contrast. However, it did require operators with perfect binocular vision, which the British claimed made it difficult to man them. They also claimed that stereoscopic rangefinders were fatiguing to use.

As best I can tell, the claims are entirely baseless. The US adopted the stereoscopic rangefinder in the interwar years, and never had any issues finding sufficient personnel. On the difficulty of use, a US report summarized the results of US research by stating “Indeed, the general conclusion to be drawn from the experiments outlined in this chapter of the present report is that stereoscopic range finding is curiously, and gratifyingly, resistant to psycho-physiological changes in the operator. This is true for fatigue, loss of sleep, drugs such as metrazol, oxygen deprivation, and postural changes.”

https://www.navalgazing.net/Rangefinding

Edited August 8, 2020 by akd