Hi there
It's a very interesting thread with lot's of great info and pictures. I have a while to spend here, so I think I can add something usefull. I second the mlespaul info about artillery panoramic sights. I have found similar info about them - standarized and somewhat "traditional" artillery equipment, not changing much over time. By standarised I mean that Russians could use German sights in their artillery pieces and vice versa, and it was done often - all were based anyway on original Goerz artillery panorama, and all were very similar and sometimes almost the same (and interchangeable). Almost any standard artillery sight could be used for almost any artillery piece from any nation, excluding some lighter AT guns. The same Russian sight could be used on 76, 85, 100, 122, 152mm guns and howitzers, and also on all self propelled versions as well (at least Su-76 used standard one, and others most likely could use it too). Even older WW1 sight could be used in WW2 gun. The reticle in Russian PG could be simple cross or a grid like mlespaul said. Probably at some stage of war, when field guns and howitzers were so often used to combat tanks, and even self-propelled versions (which usually had a second direct-fire telescopic sight - not Su-76) often had to use artillery sights to fire at tanks at more than 900-1200m range (telescopic sight was usually scaled only to about 1000m) then came to idea than adding an "arrow" aiming point and some horizontal marks similar like in newer tank sights (TSh-xx family) could be a good thing for both aiming at moving targets and training of tank/artillery gunners. I mean having similar aiming aids in artillery/tank sights could be good thing. So the more advanced version of aiming grid was introduced in artillery sights, I would GUESS that it was in about the same time, or little after, than TSh-1x family of sights were introduced, as the symbology is very similar. So early war vehicles/guns using just a cross could be quite accurate modeling - this is a guess as I said.
Here is a VERY interesting page, with lots of info about guns and artillery (explained from the very basics to advanced issues), chapters about ways of laying the guns (historical, ww2, sights), AT gunnery (ways of aiming), and much more interesting things (like what factors affect gun accuracy), I learned a lot about artillery sights here:
http://members.tripod.com/~nigelef/sights.htm
http://members.tripod.com/~nigelef/anti-tank.htm
OK, I have some additional pictures of PG-1 "Goerz artillery panorama" to share. They come from a book
Guns in Russia
1943 MOD.D-1 152mm Howitzer
(contains large amount of reprints from original gun manual)
full pages,
page 31 contains optics data
magification x4, field of view 10deg
page 33 contains the sight itself and the grid/reticle drawing
and drawings of the sight itself
and the reticle/grid only.
It's not said if specific picture is from war-time or post-war manual, as various sources are said to be used/reprinted. Here gose the late-war/post-war PG-1 reticle/grid scheme. The lower horizontal scale is said to be from separate collimator and has probably something to do with finding bearings while aiming with gun. Didn't translate full text to find how this works.
This specific drawing is quite accurate IMO, but it's good to remember that any reticle drawings are most likely a simplified schemes, not in scale and often with less important details missing - just to show the general sight layout. What is need to actually draw a realistic sight for a game is a knowledge (or a scheme) how the various reticle elements are sized and positioned (for example an info that vertical marks are separated by 5 mils (0-05 in Russian text) and the size of the central "arrow" (or inverted V) is probably same as in TSh-1x tank sights, so:
you can do the math and recalculate the height and width yourself
or have it here, I did it before:
The best source for modeling game sight are of course actual photos of working sight reticles, like mlespaul posted. It's an actual view, not a simplified scheme like on most drawings. Only thing to remember is than it's hard to make a photo showing full FOV of the sight with an ordinary camera, in most cases only the center of the FOV is visible on photo so the reticle grid and elements appear to be larger (in relation to visible part of FOV) than in reality. The knowledge of true size (in mils) of reticle elements (combined with known sight's FOV, 10deg in case of PG-1) helps in determining the real scale and how the sight with it's whole FOV should look.
I believe the drawing I'm posting 1943modd1152mmhowitzerpzn1.th.png could be close to actual look of the sight when someone looks trough it - the elements of reticle seem to be about the proper size.
The horizontal "lead angle" marks are said to be set every 5 mils (different than in TSh-1x tanks where it was 4 mils). The central arrow seem to be the same size as in tanks (4 mils wide each side), the "empty" space (no cross) around the arrow head seem to be 2 mils (same as "empty" area below the arrow in tanks). The vertical size of horizontal marks would be 1 and 2 mils. It's hard to tell this for sure from drawings and picture but it seems so and seem logical.
Now, the scale with 8 horizontal marks, 5 mils each, cover 20 mils each side of the central arrow, 40 mils all . The whole sight FOV is 10deg as we know. On drawings, the horizontal scale (8x5mils) is about 1/4 of the sight's FOV. One mil is (as Russians assume in the same paper) 1/6000 of whole circle, so 360/6000 = 0.06deg (actually more precise calculation would make 1 mil = 0.0573deg). Now the width of the horizontal "lead angle" scale - 8 marks by 5 mils = 40 mils, multipled by about 4 (as it covers about 1/4th of the sights FOV on drawing) would be about 160 mils, this is 160*0.06deg = 9.6deg. Quite close to the 10deg it should be theoretically (from optics data). So the drawing is close to how actually the sight should look like.
(more exact measurement made later:
the size of the whole horizontal scale, 8 x 5 mils (both left and right) is 136 pixels. The size of the whole FOV (10deg) is 560 pixels. The proportion 560/136 is 4.118 so little more than 4.
4.118 x 8 x 5mils = 164.706mils - this is the width of sight's FOV on drawing. And 164.706x0.06=9.88deg so even closer to theoretical 10deg. Maybe the size of the grid plotted on the optical plate is indeed a little bit smaller than the FOV of the optics and there is really a "circle" visible little smaller than optical FOV, as a part of reticle close to the edge - like in all stock RO optics ? Only an actual look (with an naked eye) trough real sight could tell it probably, as no picture made with ordinary camera is likely to show the whole sight's FOV as seen by human eye... But the edge could be photographed probably separately.
The conclusion - proportions on the drawing
are almost exact, so it's probably not a simplified scheme but a correctly scaled drawing of actual reticle grid - or very close to. Can be used directly while making PG-1 panoramic periscope sight texture for RO (excluding the lower strange horizontal scale with lot's of numbers- it probably cames from separate device and would be not visible or used in AT gunnery. )
Regards!!!
Amizaur