[Hitman]

First of all, I would like to put well clear that I do not by any means claim to have the absolute knowledge about U-Boat optical systems. Far from that, there are way many things I still don't know, rather than know. However, I have been for several years already doing a research as in-depth as possible on the subject, and that includes not just the internet, but also exchange of e-mails with the Zeiss corporation historic archives, some questions to one of the few remaining U-Boat commanders (Through a guy who knows and meets him regularly) and a lot more.

That said, I want to start with the page you took that info from. It's this one, which I have seen already linked a few times, and which is in fact plaged with errors For starters, the zoom is stated as 1x/6x, which is not correct, as it was 1,5x and 6x. Now, according to what I know, I will make some comments (And keep in mind I could be wrong)

you could not see through the scope unless it was fully raised. There were no intermediary positions.

Not true. You could always see through the scope since it exited the protective housing. You would however not be able to see anything else as water until it broke the surface.

Keeping the boat at the proper depth was extremely important.

True. But keep in mind the commander worked continuously with the height switch for the scope (On his left hand in the fixed heigth attack scope) to show as less as possible.

Also, raising the scopes at high depth would result in damaging the scopes.

Correct

Fogging was possible to fix when on the surface.

Correct. The scopes had special drain holes that could be opened to dry the interior and eliminate the damp.

- the periscope station (the 3d rotating one with the small seat) had the knobs/switches for rotating the scope, using color filters, zoom level, and aob/range finder wheel.

Correct. AOB/Range finder however not implemented in all models.

- the periscope bearing was only available at the top of the scope, on the static part. It was luminated by a small light bulb that rotated with the scope (easy to see in Das Boot, when the captain repeteadly looks up to see the bearing).

Correct in certain models. Not true for all of them. All observation scopes f.e. had an internal partition in which you could read the bearing. All attack scopes equipped with AOB finder had it also.

- the periscope did not have buttons for firing torpedoes (i think).

Correct.

and no, they didn't have periscope lines which changed color during the night.

Not true. Graticles were made of radioactive material, and it looked pale green in the dark (fluorescent). However, only the lines were like that. Numbers did not light in the darkness.

The aob wheel on the scope might've been actually linked to the TDC itself, but I doubt it, since it had to be reseted for normal viewing.

It wasn't.

Now the AOB dial was in fact linked to both the Bearing dial AND the compass. Changing your course also changed the AOB. The link to the bearing (the auto tdc update feature) was indeed optional. But the link to the compass was not optional. If you say a target at 45 degrees bearing wich had a 45 degrees AOB to you, and then you changed the course by 45 degrees into it, at the end of the turn, you would not have a 0 AOB at 0 bearing on the dial (As you do in SH3 and SH4), you'd have a 45 AOB at 0 bearing as it should be.

Correct. Example Source= Heinz Schäffer, "The journey of U-977"

- the Nav Officer would calculate the torpedo travel time after firing.

The TDC did that more or less. It showed the travel distance. Chronometers with appropiate scales would automatically give the time.

- Actually, the officer should be able to take your place at the scope and conduct the same procedure as you.

They certainly were able to do that! As in US subs, where the IWO was also many times the substitute of the commander, in case of death or illness.

- Of course, both SO and Nav Officer's experience would greatly impact all their calculations.

VERY true!!! The german U-Boat waffe relied more than many other Navies (Except the british, probably) in naked eye estimations for many things. Seaman's eye, as it is also called.

So far the head size has not influenced detection. There HAS to be a reason for using the AP instead of the OP, right? SUre, it must've had a vertical stadimeter, excelent for navigation, but an AOBF too? Why the different sizes of the stations then? where would you fit the mechanics?

The obs periscope had a better light admission, hence its utility for night attacks. Vertical stadimeters and AOB finders could be implemented in any periscopes, they are attached externally. (See the link below, at the end of this post)

Any change in lengths between lenses and prisms ruins the optics. Since the lenses and prisms were housed at the ends of the scope you had to line up thebottom lens to the station housing to be able to view through it.

Not true. The prism and lenses travelled a certain distance together with the scope, keeping the proportions and the ability to see even if not fully raised. In the fixed heigth attack periscope this also happened for the whole travel of the lenses.

I blame youtube for not having movies of night attacks

Most movies and pictures I have seen were FAKED periscope views. There are still certain corretc ones, though, but in those you hardly can see the reticles. Seeing diagrams of reticles in authentic scope manuals and descriptions in technical reports, you can easily notice how they don't match at all with what you see in many films/pictures.

Or simply they became "lighter" as the surrounding became dark? And for how long would they last? Is it similar to fluorescent paint that needs to "recharge" with normal light?

Yes!

Finally, here is an excellent link with information (In german) about the periscopes: http://www.uboot995.homepage.t-onlin...__zubehor.html