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Theodolite - BigBill - 03-11-2017
Hi,
New guy here. I'm more of a land navigator with the sextants and was wondering if anyone had any experience or ideas about a make and model of surveyors transit that might be best suited to CelNav.
They do come up for sale from time to time and I'd like to have something in the back of my mind to keep an eye out for if I can swing the expense.
TIA
RE: Theodolite - Rdutton - 03-11-2017
(03-11-2017, 04:20 AM)BigBill Wrote: Hi,
New guy here. I'm more of a land navigator with the sextants and was wondering if anyone had any experience or ideas about a make and model of surveyors transit that might be best suited to CelNav.
They do come up for sale from time to time and I'd like to have something in the back of my mind to keep an eye out for if I can swing the expense.
TIA
TJA,
I used to have a Keuffel & Esser transit. It's exactly like this one on ebay;
Keuffel & Esser transit
It was very good for, well, surveying, and I did use it to shoot several stars and Polaris but never the Sun- no sun shades.
It was quick to level out and to re-adjust once setup. You can probably guess that it would be easier to use a transit for shooting stars and planets at night than an Artificial Horizon, and for me it was. The only difficulty I had was using the center of the crosshairs to occult a star somewhat and then take the reading of Hs. Once I figured out how to sight the star everything for getting Hs was simple. Keep in mind you're mostly working in the dark and the crosshairs are black too. I tried putting a piece of tissue paper around the front of the telescope (not in front blocking the lens) and then shining a small LED light onto the paper. This would illuminate the crosshairs and making hitting a star easy.
The doomed Scott expedition to Antarctica used a theodolite instead of an Artificial Horizon.
The ebay transit listed on ebay, above, is going for $185. That's a good price but the shipping's not cheap.
Fair winds....
Roland
RE: Theodolite - c_davidson - 03-11-2017
(03-11-2017, 04:20 AM)BigBill Wrote: Hi,
New guy here. I'm more of a land navigator with the sextants and was wondering if anyone had any experience or ideas about a make and model of surveyors transit that might be best suited to CelNav.
They do come up for sale from time to time and I'd like to have something in the back of my mind to keep an eye out for if I can swing the expense.
TIA
Just to echo Roland's comments- an old used transit is great. I had one years and years ago and was successful in using it for sights of planets, which at the time were my only interest though I did make some star observations.
The only problem I had was the levels in their tubes needed calibration since they weren't level. Once adjusted properly, which took about 2 hours of my time, all was well.
This goes without saying that if you're buying a used transit make certain the cross hairs are intact and not bent or broken.
Good luck.
Clen
RE: Theodolite - BigBill - 03-11-2017
Thanks for the swift replies.
Can you tell me how fine a sighting is possible with one of these? I've seen many that can't do better than 15' though maybe there is a trick I don't know about.
Not that I think I'll wind up with a transit of my own very soon but things have a way of turning up at a flea market or garage sale at just the right moment on occasion.
My general interest is in the old N.African desert explorers of the '20s and '30s. Bagnold, Almasy et al and going into the desert navigation of WWII and of course that thrill of locating my place here by points of light out there.
RE: Theodolite - Rdutton - 03-11-2017
(03-11-2017, 02:25 PM)BigBill Wrote: Thanks for the swift replies.
Can you tell me how fine a sighting is possible with one of these? I've seen many that can't do better than 15' though maybe there is a trick I don't know about.
Not that I think I'll wind up with a transit of my own very soon but things have a way of turning up at a flea market or garage sale at just the right moment on occasion.
My general interest is in the old N.African desert explorers of the '20s and '30s. Bagnold, Almasy et al and going into the desert navigation of WWII and of course that thrill of locating my place here by points of light out there.
TJA,
If my memory serves me correctly the horizontal limb of my K&E could be read down to 0° 01' (1 minute of arc). That's the best I can remember.
Most of the difficulty in using a transit (sextant, too) is leveling it and keeping it level after setup. The remaining complications are often just related to reading the vernier.
You have a very unusual interest to say the least. North African explorers! Do you mean Ralph Bagnold?! What a man he was!
Have you followed anything about the LRDG's during WW II?
Though related to problems in air navigation, have you ever seen the movie, "Sole Survivor" with Richard Basehart? It's a movie loosely based on the flight of the "Lady B-Good" during WW II.
Here's the entire movie- Sole Survivor
Yard sales are great as eventually someone wants to sell "some old mechanical thing with a telescope on it" owned by their now long gone uncle.
Good luck,
Roland
RE: Theodolite - BigBill - 03-12-2017
(03-11-2017, 11:56 PM)Rdutton Wrote: TJA,
If my memory serves me correctly the horizontal limb of my K&E could be read down to 0° 01' (1 minute of arc). That's the best I can remember.
Most of the difficulty in using a transit (sextant, too) is leveling it and keeping it level after setup. The remaining complications are often just related to reading the vernier.
You have a very unusual interest to say the least. North African explorers! Do you mean Ralph Bagnold?! What a man he was!
Have you followed anything about the LRDG's during WW II?
Though related to problems in air navigation, have you ever seen the movie, "Sole Survivor" with Richard Basehart? It's a movie loosely based on the flight of the "Lady B-Good" during WW II.
Here's the entire movie- Sole Survivor
Yard sales are great as eventually someone wants to sell "some old mechanical thing with a telescope on it" owned by their now long gone uncle.
Good luck,
Roland
Yes, Ralph Bagnold. His pre-war adventures should be made into a movie. Considering that Almasy was also a real person and they made the fictional English Patient using him as a character you'd think the actual events would make a better more genuine film. Funny, I watched Sole Survivor about a month ago.
Not that I'll ever get the chance but I'd love to get out into the deserts and try my hand navigating.
Thanks for the tips
~Bill