Telemeter Scale's usage.

[hanz079]

Just to share that I have finally found out the use for the telemeter scale on my Zenith Rainbow Flyback.



Tachymeter scale is the norm when marking the outer rim of a chronograph.
On my Zenith, it is a Telemeter scale that was used instead.

After some digging, finally found out it's purpose.
It is used as a reference as to how far a sound is by timing the light.

EG: Since it's CNY, if I see some fireworks, at the moment the fireworks explode (Light), I start the chronograph.
And stop it when I hear the boom (sound).
The needle pointing at the scale is the distance in kilometers between the explosion and you.
Trivial I know but useful nonetheless... 

[TheHobbit]

Cool...... Me still use old way. See lightning, start counting until you hear thunder. Divide by 5 and you have the distance in miles.....

[STT1987]

It's got to be a pretty fantastic explosion / lightning bolt to be seen and the sound to take 60 seconds to reach the observer! Visible from 20km away!
      

[1to12]

I was wondering what a Telemeter was when I saw it on a FM piece. Googled then and found similar explanation. Not sure if it's practical now but probably used in the earlier days to measure somethings or for military usage.

[TheHobbit]

Military usage, may not be relevant today.....

The telemetre chronograph was designed for use by officers in trench warfare during WWI. It is used when the officer is trying to range artillary fire. The officer would use the chronograph to measure distance with time. The officer would start timing as soon as he see the flash of a cannon muzzle. Upon hearing the report from the cannon, he would stop timing. Reading off the scale, the officer would know the range to the enemy artillary.

[Calibr]

Military usage, may not be relevant today.....

The telemetre chronograph was designed for use by officers in trench warfare during WWI. It is used when the officer is trying to range artillary fire. The officer would use the chronograph to measure distance with time. The officer would start timing as soon as he see the flash of a cannon muzzle. Upon hearing the report from the cannon, he would stop timing. Reading off the scale, the officer would know the range to the enemy artillary.

Wow.. really good stuff here. Next time I watch a movie of WW1 or WW2, I'll keep on eye on what watch they used for this purpose!

[jason_recliner]

Cool info - I never knew that.  Thanks for sharing!

[Zarium]

Just like many other things, the telemeter is probably just a thing of the past now. It's there because it has always been there...not because it's actually useful anymore.

[STT1987]

It's useful for counter-battery work. You find out where the enemy artillery is determining the location and the range (via the telemeter). If you have several observers doing the same thing from different locations, you can triangulate your data and zoom in pretty accurately on the enemy artillery battery - then you open up with your own artillery and whack that sucker. Nowadays, it's all done with radars that can track the artillery shells back to the howitzer location.

This is why, most modern front-line artillery are self propelled guns (artillery guns mounted on tracked/wheeled AFVs). You can't stay in one location for very long - need to "shoot and scoot."

[takashi78]

Cool info Hanz.
Never noticed it was another type of scale on your Rainbow.

Wonder when this model came out what was the true "intended" purpose of the designer.

[kltime]

Cool stuff, I learn something everyday 

[Gigi]

Cool info Hanz.
Never noticed it was another type of scale on your Rainbow.

Wonder when this model came out what was the true "intended" purpose of the designer.

The watch was made for frenchie pilot when its designed. not sure how telemeter work when u are on jet aircraft

[Watchnewby]

Cool information there from Hanz and Hobbit. I never knew that until I read this thread. Thanks for sharing, Guys!

And Gigi, IMO, for pilot there is the Pilot or "military pilot" watch to help the pilot measures whattever he wanted to measure in the sky. Just my 2 cents.

[squasub]

thanks Hanz for this info..

practical or not for me its a cool function to have!