There's another wrinkle to consider though. With the DVD version of US Topo, you cannot install the full US on your GPS. This has to do with the size "tile" that the map is broken down into. There are about 6,600 map tiles in US Topo, but the Oregon can only display 4,000 tiles total
I also agree, the included 100K Topo is really bad, but you can, and should, make complete backups of the units before doing anything else. Then install any new maps you want!
I have never seen a spec, but "assumed" the Montana has a 4,000 tile limit like all the other newer handhelds. So you could only load 2/3 of the US. But really, if you really want the full US topo you should buy the download or SD card version. They only have ~450 tiles, so that leaves capacity for a lot of other maps. Since I haven't ever used those formats, I'm not sure if the download/SD versions are locked to a specific unit, but I'm willing to bet they are.
So, for example, if you used 1 foot/pixel source imagery you could only cover 1.9 miles x 1.9 miles on the Oregon, 62s or eTrex 30. But on the Montana you could cover 4.3 miles x 4.3 miles
Hi Boyd. How big of a state are you covering with a 4 GB card?
State? Haha very funny. I have given you the rough numbers in my post. Figure 300 square miles per gigabyte for highest quality and 900 square miles per gig for high quality. These are just rough estimates. You can do your own tests too.Now do a google search for the size of different states. You will see that Rhode Island is about 1,500 square miles. So you probably couldn't fit all of that on a 4GB card at highest quality.
Well that was fun Boyd. Just crunching the numbers comes up to an SD card for Minnesota of about 250 GB. You got one in your pocket? Thanks, Bud
Yes. In fact, I gave my Oregon to a friend along with a 16GB card full of expired Birdseye from two years ago. I told him not to register the unit in his own name as long as he wanted to continue using that imagery.
I'm not sure if that really would have mattered anyway, but better safe than sorry. However, you can move the imagery to another GPS without actually downloading again. That's what I did when I got my Montana. I then subscribed again and was able to unlock the Oregon files on the Montana.
Yes, Birdseye is just like City Navigator. Only one device per subscription.