Optics often come up in discussions that compare Soviet and German tanks. The famous "Zeiss optics" are often invoked by those who are not very well versed in the subject matter. The issue was not in Soviet sights. Plenty of them survived to this day, and any who wish can evaluate their quality on their own. German tanks were first and foremost superior in their observation devics. Their visibility was better than that of Soviet tanks, which was often a deciding factor in victory on the battlefield. However, the evolution of German observation devices is an interesting topic for discussion.
Pre-war evolution and lessons from Spain
The Germans did not have an advantage in observation devices right off the bat. The observation devices and sights used on German tanks after 1933 were the result of a long evolution that is often forgotten. Successful designs are often reached via trial and error. The Germans were not an exception here. Work on observation devices began during the First World War. The commander's cupola as we know it appeared back in 1918 on the Sturmpanzerwagen Oberschlesien that remained on paper and LK-II that was built in metal after all and is better known as the Strv m/21.
A variant of this tank with a turret and a machine gun was built during WWI, but there was no time to finish it. Joseph Vollmer's design that didn't quite make it to the battlefields of WWI had quite good visibility for its time. It had a commander's cupola with observation slits and observation devices in the turret, some of which could be closed with armoured shutters. Compared to this tank, the Renault FT looked like a cramped and blind tin can. Swedish tankers who tested a Renault FT said the same thing. It had a commander's cupola, but you couldn't see much from it. The LK-II still suffered from the typical issues of tanks of that era, namely that the observation slits weren't protected and fire aimed at them could harm the crew.
|The LK-II had a commander's cupola and vision slits, some of which could be covered with shutters. After the end of WWI these ideas were lost.
|Periscopic sights were common for pre-war German tanks.
|Sweden picked up German pre-war tank design ideas. The Strv m/31 and other tanks that were built there show signs of German influence.
|Initial draft of the Nb.Fz. tank. This was a pivotal vehicle for German tank building, as many observation solutions migrated from this tank to other German tanks.
|The Germans settled on the horseshoe shape for their tank turrets starting with the Pz.Kpfw.I. This tank also heralded a new era for tank observation devices.
|The Pz.Kpfw.II tank had a combat driving vision device, a typical feature of German tanks.
|Improved observation devices that appeared as a result of studying experience from Spain.
|Driver and commander's vision ports on German medium tanks in 1939 looked like this. These were some of the best vision devices at the time, but it turned out that using glass blocks was not the best idea.
The issue with protection for observation devices also had to be corrected on the commander's cupola. The existing design with no protection for its vision slits was vulnerable to small arms fire. However, the Pz.Kpfw.IV Ausf.A and Pz.Kpfw.III Ausf.A and B still had the old vulnerable design. Starting with the Pz.Kpfw.III Ausf.C and Pz.Kpfw.IV Ausf.B the tanks had a new cupola with a special shutter to protect the vision slits. This cupola design lasted for a very long time. The Pz.Kpfw.IV Ausf.B also received a new driver's vision device, the Fahrersehklappe 30. It had two shutters that slid up and down, offering more reliable protection. This device was also used on the Pz.Kpfw.II Ausf.E and used until mid-1940. It later appeared on the Pz.Kpfw.II Ausf.F. This device was designed to protect the driver from high caliber machine guns. New Sehrklappe vision ports were also introduced. These were larger and had thicker glass blocks.
By the start of the Second World War the Germans walked a long path developing their tank optics. By that point they were the clear leaders in observation device design. There were certain drawbacks, but those will be discussed later.
The Polish Campaign revealed some issues with German observation devices. The medium tanks were more or less okay, at the very least there were no obvious issues, but evidence still pointed to deeper problems. The Fahrersehrklappe 30 didn't fully protect the driver from shell splinters or bullets larger than rifle caliber. The system with lifting shutters took up too much space and could jam. A new variant of the Fahrersehrklappe 30 was introduced in the spring of 1940 as a result. There was only one shutter instead of two that reliably covered up the observation slit. A new commander's cupola was also developed. Its shutter was split into fragments that could be raised and lowered individually.
|Medium tank observation devices were improved as a result of the Polish campaign. Further improvements were limited to thickening their armour.
|The Pz.Kpfw.II's commander's cupola was the first instance of prism periscopes being used on German tanks.
|The Germans copied the Gundlach periscope, but only in part.
|An example of German conservatism. The Tiger (P) had no periscopes at all.
|Observation devices in the Tiger Ausf.E.
|Observation ports were priority targets for infantry.
"The entire commander's cupola had flown off my "Tiger". I had shrapnel in my temple and face. The wounds bled profusely, of course, but nothing had happened otherwise. The entire affair could have turned out considerably worse. Kramer had always chastised my smoking. But he had been taught a lesson; if I hadn't bent over to light up my cigarette, then my head would have been in the cupola at the critical moment. It hardly needs to be mentioned that I would have "lost my head" in the truest sense of the word.
I wouldn't have been the first one that had happened to. The reason could be found in a design failure. On the initial "Tigers" the cupola was still welded. It rose up high and had direct vision slits. The cupola hatch stood up vertically when it was opened. Thus, from a distance, anyone could recognize that the tank was vulnerable from the top.
A high explosive round only had to hit the hatch and the entire charge then came down on the commander's head. If a commander wanted to close the opened hatch, he had to lean over on the outside of the vehicle and expose himself to the hip to unhitch a safety latch that released it."
Another thing mentioned in Carius' memoirs is often counted as a positive. German commanders often fought looking out of their turrets. Carius considered this an advantage over Soviet tanks. This fact brings up an interesting consequence: the vision of German tanks was still insufficient. A head sticking out of a turret was a priority target in battle. Carius admitted this himself and later acquired a binocular periscope to look through.
|The Panther was in a similar boat when it came to observation devices.
|The Tiger and panther later received new commander's cupolas, but they were still very tall and vulnerable.
|The situation with observation devices on the Pz.Kpfw.IV by 1944 was dire. There was no way to look sideways aside from the commander's cupola. The vision ports in the turret hatches were covered by spaced armour.
|German tanks were extra vulnerable from the flanks by the end of the war, the same thing that happened to Soviet tanks in 1941-42.
|The Germans were capable of making rotating periscopes, but didn't put them on tanks.
The situation with tank production in 1944 had its effect on tanks. The German "beasts" had to transition to monocular periscopic sights. However, it's not hard to notice that the crisis began long before the situation became difficult. Other nations had their own issues, but the overall picture is clear: while everyone else's tanks got better vision, the Germans only got worse.