Hello from Russia!
The issue with the optics soviet tanks we (here, in Russia) understand has long time ago.
Soviet sights were good enough. A optical glass - no.
Optical factory is located in the western European part of the country. And with the start of the war, they were under attack.
Some were captured. Some were evacuated to the Urals. Some in the siege (as Leningrad).
The result for the industry was the same: lack of optical glass. Then it's time ersatz.
The problem of Soviet bad optics was solved only with the help of Lend-Lease (hooray allies!). This means that in 41-43 years soviets has bad optics, and in 44-45 it was already on par with the Germans (especially considering decline quality of German optics as a result of the ally bombing).
coh2player tell about IS-2 right. Of course, he was not a tank hunter. 25 kg projectile for tank hunt? The obvious overkill.
About SU/ISU-152 not quite. They are supposed to be used against fortifications, like the KV-2. Their use against tanks was improvised. Like using a 8.8 cm Flak against British and French tanks.
P.S. I was always surprised that СoH2 USSR are rushers and the Third Reich are defenders.
I mean that the Allies did not beneficial to delay the fight, while the Germans on the other hand, benefit from access to the late phase. CoH2 and history? This just ridiculous.
P.S.S. My english just lame. I know.