"Effect of using telescopes on battlefield" Topic

I seem to recall reading somewhere that early 19th century telescopes had a magnification factor of about x 3. My question is: would using such a telescope simply mean that by using a telescope one could, for example, distinguish infantry from cavalry at three times the range one could normally do so with the naked eye? Or is the effect more complex to determine? Any comments by those knowledgeable in such matters would be greatly appreciated. Thank you in anticipation.

I have bought some weeks ago a tiny telescope with a magnification factor of x8 and I must say that I have found it useless….

Google library has a German book titled "Military paperback for use in the field" ("Militärischs Taschenbuch zum Gebrauch im Felde") by G. Scharnhorst, Captain in the Royal Brit./Hanovr. Artillery Regt. & lector at the Hanover Military School, published Hanover 1793. I think he is the later Prussian chief of staff in 1813, killed at Lutzen that year. He has the following to say in his appendix chapter titled "finding or estimating distances":
His notes say that the ordinary perspectives, commercially available, are of little use as most have only negnectable magnifying ability. Reflective telescopes (Spiegelteleskope) are better here, but are not sharp at all on the longer diastances. Best are the more pricey "Dollond" type or "achromatic telescopes" (i.e. the London manufactor – google has more on him). They cost you 4 to 5 Louis d'Or – if I read his currency converter right this should roughly equal 4-5 Engl. Guinees. The acromatic tube measures 5 inch to 14 inch if all extended and has a magnifying scale of x12 to the unassisted eye.

Estimating distances with the eye only, he gives the following data: At 2000+ You cannot distinguish troops. Infantry can be identified by their glancing musket barrels only. If you can see the files, it's cavalry at this distance. At 1500 paces you can distinguish the files of infantry. At 1000, you can tell the heads from the bodies at times and at 600 at all times (enemy is now entering cannister range). 400-300 you can see the faces, and uniform detail. 100-70 you see the enemies eyes as black dots.
In order to use a telescope for getting a distance, Scharnhorst recommends some preperation to be done in advance. A micometer scale has to be fitted to the linse and basic distances have to be traced out in advance, kept in memory, and thereafter can be applied to your object under observation.

Hope this helps,
Christian

I feel the telescope would have been fairly useful in Artillery units and commanding generals trying to scope out terrain in the distance or to perceive movement from long off…

Magnification is only one aspect. Many modern sniper scopes are only 3X and 4X power. Distortion (the blurring of part of the image with another part) is the important thing. Your brain has to understand the pattern of what is presented to your eye. Some of the blur would be from poor lens design, some would be from imperfections in grinding the lens, some of it would be from chromic aperation (e.g. different colours of light focus differently. A big objective lens (nearest the object) collects more light and helps as well. Dust, smoke, mists, humidity and temperature variations in the air also bend and scramble the light bouncing off of objects. I've seen various wargame tables of "how far you could see how big a thing" that are ballpark okay.

According to Coignet Moreau was killed at Dresden with fire directed by telescope. Interestingly he records that Napoleon spotted Moreau with his small (ie pocket) telescope but the gunners were directed using his big telescope. Now we do not know what ranges were involved but it seems these were the Emperor's regular telescopes – not specifically calibrated for artillery. The horse was hit along with Moreau's legs. Coignet is very specific in the details of this event so I'm inclined to go along with him. Are there other instances of long lange artillery sniping before the advent of rifled artillery?

Crogge1757 have you got a link to Militärischs Taschenbuch zum Gebrauch im Felde as google can]t fibd it LOL

thanks Ian

crogge1757 do you have a link to Militärischs Taschenbuch zum Gebrauch im Felde as google can't find it LOL

Thanks Ian

Hi Ian,

go to books.google.com
advanced book search and type in Scharnhorst as the author. Then you should see "Militairisches Taschenbuch, zum Gebrauch im Felde…" on the first page (and I have to look up how to post a link, at least the preview of this message looks rather queer…)

regards Norbert

Funny, the submitted message looks different than the preview of it. So here is the direct link:

link

some of it would be from chromic aperation

Do you mean chromatic aberration? That's what it sounds like you're describing, and it is spot on.

yes- my fingers did a garbled phonetic spelling.

By the ACW they had binocular field glasses. Did/does the stereoscopic affect help much with judging distances?

Just a caution about some comments I saw above about ranges (I think) ranges being embossed on the glass inside of telescopes. It didn't happen.

As to the question about binocular field glasses….A range-finder (think the two scissor lenses about 2 feet apart above a WWII artillery observer or the big ones 40 feet apart above WWI battleships) work by simple trigonometry. Bring the two images together and if you know the distance of the base (you built it!) and the angle to the target (thats what the thing is build to measure), you can figure out the length of the side and distance to the enemy. A telescope has only one viewer. A hand held binocular doesn't have much distance between the objective lenses. Bringing things into sharp focus as a range finding method doesn't work well beyond 50 or so feet- just like a camera with f/stops. Beyond a moderate distance, there is not much difference in the angles that the target takes to focus.

If you know the height of an object or the length (from measuring the length of the enemy's battleship before hand)and can measure the angle between the two ends and calculate the distance. This would work for a telescope. Hence the false bow waves painted on a lot of ships even in WWII. But on land, there aren't as many know big markers out there.

Napoleon, of course, had access to laser range finders, which helped a lot except for foggy or smoke hindered days. But that's another story.

Yeah, and his heat-seeking 12-pdr shells!