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    Re: Calibrating a sextant scale
    From: Paul Hirose
    Date: 2007 Nov 22, 21:10 -0800

    Alexandre E Eremenko wrote:
    > 
    > I understood from your previous message
    > that you have a theodolite and collimators
    > and you are going to make these tests soon,
    > and tell us the results for the three sextants
    > you mention.
    
    You have me confused with someone else. I have three theodolites and a 
    couple bubble sextants, but no marine sextants and no collimators.
    
    >>From time to time I look for a theodolite there,
    > and the price of a Wild T2 that you mention is well
    > over 1000 bucks, usually closer to 2000.
    
    The Kern DKM2 is another 1-second theodolite in the same class as the 
    Wild T2. I think both instruments were designed by Herr Wild (he left 
    his namesake company and went to the Kern company). Someone once sent me 
    a DKM2 to examine and possibly buy. I think he wanted $750 for it. An 
    instrument shop examined it and found that it was in good shape but 
    needed adjustment. I decided not to buy. The guy who ran the shop said 
    the DKM2 was the hardest of all theodolites to adjust. (He graduated 
    from the Kern school in Switzerland in the 1970s.) The later DKM2A model 
    was easier to work on, he said. There was one in new condition at his 
    shop, and he offered to sell it for $1800. That was too high for me. 
    Since then I've regretted not taking the offer.
    
    The Zeiss Th2 is also a 1 second instrument. They don't come up for sale 
    often. The man who runs Swisstek offered to sell me one, fully 
    calibrated with a warranty, for $4500. That price may be OK for a 
    professional, but as a hobbyist (who is not rich) I can't justify 
    spending that much.
    http://www.gmat.unsw.edu.au/currentstudents/ug/projects/f_pall/html/
    
    Here's a guy who's selling a Th2 with a night illumination system and 
    right angle eyepieces. It sounds like a great setup for celestial 
    observations, but he wants $3000. That's still too much.
    http://www.antiquesurveying.com/transits_and_theodolites.htm
    
    The other Zeiss company (Zeiss Jena) also made a 1 second theodolite, 
    the Theo 010. I see them on eBay once in a while. Never handled one, though.
    http://www.gmat.unsw.edu.au/currentstudents/ug/projects/f_pall/html/
    
    I own a Russian theodolite (ТЕОДОЛИТ 3Т2КП on the cover of the manual) 
    which reads to 1 second. It doesn't have the fit and finish of the Swiss 
    instruments, but it works and only cost $1200 new! However, the company 
    that was distributing them in the U.S. is out of business, I think.
    
    The Wild electronic theodolites may be worth looking at. They seem more 
    affordable than the old opto-mechanical models like the T2 and T3, 
    probably because they don't appeal so much to collectors. I've seen 
    T3000s sell for well under $2000. I once worked at a place which had 
    some T3000s in the tool crib, so I've played with this model a bit. It's 
    a beautiful instrument. Resolution is .1 second! It has digital LCD 
    angle readouts. The internal computer automatically compensates for 
    index error, horizontal collimation, etc. It removes the errors 
    mathematically so you don't have to fiddle with little adjusting screws. 
    There's even a fluid sensor to detect and cancel out the effect of minor 
    dislevelment. I may buy one of these someday.
    
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