[Taxacom] GPS units that record the time a waypoint was taken

Sean Edwards sean.r.edwards at btinternet.com
Thu Mar 19 04:36:48 CDT 2009

Yes, you are right, my Canon at least requires a plug-in module (oddly, the 
"Wireless File Transmitter WFT-E2"), which is not particularly cheap either, 
but I think that other Canons incorporate the module into a battery pack (5D 
MkII) etc., I'm not sure, and I guess it is only a matter of time before the 
software is built in as you say it is with the Nikon.

By the way, I would stress that you can't just plug any GPS unit in -- it 
must have the correct transfer protocol. I think that this is NMEA 0183 but 
do check.

I guess that accuracy is that of the GPS unit, which with WAAS/EGNOS I find 
takes me to within a few metres (1-3?) of a site revisited. Obviously it 
depends on how many satellites it can see, and also how long you have not 
moved from the site -- 10 minutes does seem to focus much more tightly from 
an initial lock of maybe 5(+) metres away.

However, I also notice that the Canon record of the location is one decimal 
point short of the unit's -- minutes with three points compared to the 
units' four. I think that this means that conversions to e.g. the British 
grid (which goes to the metre), may only go to a 10 metre accuracy?

I'm not sure how much of this is spurious precision rather than accuracy, 
and I would appreciate comments, please?

I think I would never buy a camera with the GPS itself built in, but would 
appreciate not having to buy an expensive module with features I don't want 
to plug it into, and that makes the camera even bigger and more awkward.

That said, the system I use works like magic, and isn't really that bad a 
blimp on the side since the camera is a tank anyway. The USB cable can be a 
bit of a nuisance, but not much.



Sean Edwards
email: sean.r.edwards at btinternet.com 

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