That document tells us very little, if anything, about the capabilities of the German rangefinder system during the war.
Firstly, though the stereoscopic range takers at the trial are described as having two years’ experience with stereoscopic rangefinders, that doesn’t mean that they were as proficient as German rang takers, trained at the Gunnery School in Sonderburg, which (at the time of Jutland) had 8 years of institutional knowledge in the use of the stereoscopic rangefinder. And whose range taker courses flunked a large part of the participants each year.
The proficient use of a stereoscopic rangefinders takes more skill that the use of a coincident rangefinder. As we can´t know if the range takers in the test were trained to the same standard as war-time German range takers, we can´t on the basis of that test safely conclude that there were no significant difference in precision between German and British rangefinders during the war.
Also that test tells us nothing about the German rangefinder systems capacity for producing data under realistic combat condition.
Thirdly it ignores the German approach towards range finding in general. The Germans knew that the mean rangefinder range, based on several range cuts, would be a lot more precise than any single rangefinder measurement. That was the motivation behind the development of the Mittlungsapparat, which gave the Germans an advantage over the British in range finding.
Optical RFs couldn't take enough ranges/minute with sufficient accuracy to build up a good range plot in the time required
This just shows that one must be careful in concluding anything on the German rangefinder system on the basis of that test. Because the Germans at Jutland were able to calculate range-rate on the basis of rang cuts.
Both von Hass and Mahrholz states that they during the approach of the two battlecruiser forces noted down the time and mean rangefinder range at that moment (in practice the same data collecting as the British Rangeplot) and calculated the range-rate from this data. This calculated range-rate was then compared with the one found on the EU/SV-Anzieger (in practice the same as the British Cross-cut, although only for range-rate). It is in this regard significant that both Lützow and Von der Tann used a range-rate of -400 m/min. during the approach, which was very close to the actual range-rate. Later (c.1917) the German Gangmittler gave an accurate range-rate in 1-4 min. based on ragefinder data. If this Gangmittler was ever tested under battle conditions is not known.
Were not the Germans rather more successful in this respect? In part this might have been due their choice of stereo rather than co-incidence type range finders. The former possessed some advantage under certain poor visibility conditions and the longer base length was advantageous.
I am certain that the German rangefinder system was much more capable to supply rangefinder data to the fire control system at Jutland that the british. For example Von Hase states that his rangefinders rarely measured more than 300 m. different from each other, while during the approach Von der Tanns rangefinders was all within 100 m. of each other.
The reason for this superiority is an open question. I do not think the base length had much to do with it. The German rangefinders base length was only 26 cm longer than the British. Not enough in my opinion to make any difference. Other possible explanations are:
Better trained German range takers. I think it is safe to conclude that the Germans had better trained range takers than the British.
A better integrated rangefinder system in the fire control system. The RW gave the barring to the target to the rangefinder which made it much easier/faster to start ranging on a target.
Weather conditions favored stereoscopic over coincident rangefinders.
Vibrations didn´t effect Stereoscopic RF as much as coincident RF.
German rangefinder readings were sent electro-mechanical to the fire control station, whereas British rangefinder data was transmited by phone or voicepipe (except for the Argo rangefinder), making for a faster and less error prone transferal of data. I think this is correct but I am not sure how The British turret rangefinders transmited there data. Does anyone know?
The Mittlungsapperat was a fast and precise way of calculating the mean rangefinder range, whereas the rangeplot was not.