#143034 - 08/06/08 04:31 PM
Re: Brunton compasses
[Re: Jeff_M]
|
Addict
Registered: 07/18/07
Posts: 665
Loc: Northwest Florida
|
I found this comment on the Backpacking light forum about the Dakar to be instructive: ...the Dakar (like the Alpin Pro) does not have lines on the bottom of the capsule to line up with meridians on the map. You have to eyeball north on the compass with the meridians on the map in order to get a bearing from the map. To me, that negates the 1 deg. accuracy that you supposedly get from this compass Still, the Dakar is intruiging... No orienting lines on the capsule? Well, that's a deal breaker for me. To bad, since the other features make it so appealing. Back to the ol' Ranger . . Thanks for the good intel. On second thought, I'm pretty sure I could fix that little oversight with a straight edge, and X-acto knife and a bit of paint. I may get one anyway, Jeff
|
Top
|
|
|
|
#143038 - 08/06/08 05:00 PM
Re: Brunton compasses
[Re: Glock-A-Roo]
|
Sheriff
Pooh-Bah
Registered: 10/12/07
Posts: 1804
Loc: Southern California
|
This compass would probably OK just for map use, but if you're really interested in cross country (off trail) navigation, orienteering, or anything that requires precise readings, this compass isn't going to get you there. With this compass, there is nothing to sight with. You have to look up at the sighting object, look down to the compass, back up to the object, and then back at the compass. No offense intended, but those 1/2 degree markings are a bit of a joke on a compass of this design. http://www.thecompassstore.com/54lu.html...Not really. The 54LU allows you to see the target, compass and azimuth all at once. It is a favorite of the guy who runs MapTools. However, it does not have a declination adjustment. Since it uses a card and not a needle it would be more affected by a bubble. I don't own one, I just remember him talking about it. I understand the idea of being able to read the bearing via the optically enhanced rim of the compass. But that's not the issue. You have no precise aiming point on the compass. How do you aim it? You basically eyeball the arrow on the baseplate, looking back and forth between the baseplate arrow and the sighting object. Yes, you can read the bearing through the rim, but it's not a very precise bearing. With a compass that has a sighting device (sighting wire, sighting aperture, sighting "V," etc.), you get a more precise aiming device and therefore a more precise bearing. Hence this general class of compasses are referred to as sighting compasses. I'm not saying the 54LU is a bad compass, but if I need to take bearings, it wouldn't be my first choice. Add in the fact that there is no declination adjustment and the 54LU is a "no go."
|
Top
|
|
|
|
#143049 - 08/06/08 06:33 PM
Re: Brunton compasses
[Re: Hikin_Jim]
|
Old Hand
Registered: 03/24/06
Posts: 900
Loc: NW NJ
|
A GI lensatic compass would be great ... if only it had a declination adjustment. I wonder why the army (etc.) doesn't have a declination adjustment? I would venture that even grunts are capable of adding and subtracting. Just kidding, but how would you implement declination adjustment in a rotating card compass used in the sighting mode? With the Dakar it looks like you rotate the lubber line on the face plate, but this would introduce a parallax error when not looking down from directly above. One more argument against declination adjustment - if you make a conversion error while using a compass without adjustment, one bearing will be wrong. If you make a mistake setting the declination on your adjustable compass, all your bearings will be wrong. In North to the Pole, the author writes how they travelled South instead of North for an entire day because he set the declination wrong.
_________________________
- Tom S.
"Never trust and engineer who doesn't carry a pocketknife."
|
Top
|
|
|
|
#143051 - 08/06/08 06:42 PM
Re: Brunton compasses
[Re: haertig]
|
Old Hand
Registered: 03/13/02
Posts: 905
Loc: Seattle, Washington
|
These three are near clones of each other IMHO:
Suunto MC-2D: $49 Silva Ranger 515: $55 Brunton 15TDCL: $69
If the Suunto and Silva are purchased in the US...then both are made by Suunto in Finland. Silva, the brand name in the US is owned by Johnson Camping. They currently have Suunto in Finland make all the compasses they sell in the US. Silva purchased anywhere else in the world is made by Silva Sweden. The Brunton is a Silva Sweden product. This confusion is confusing. Brunton also manufactures some of their line here in the US. The K&R line looks interesting all around. The Dakar at $26 seems like a good one to try.
Edited by Schwert (08/06/08 06:42 PM)
|
Top
|
|
|
|
#143060 - 08/06/08 07:26 PM
Re: Brunton compasses
[Re: Schwert]
|
Sheriff
Pooh-Bah
Registered: 10/12/07
Posts: 1804
Loc: Southern California
|
These three are near clones of each other IMHO:
Suunto MC-2D: $49 Silva Ranger 515: $55 Brunton 15TDCL: $69
If the Suunto and Silva are purchased in the US...then both are made by Suunto in Finland. Silva, the brand name in the US is owned by Johnson Camping. They currently have Suunto in Finland make all the compasses they sell in the US. Silva purchased anywhere else in the world is made by Silva Sweden. The Brunton is a Silva Sweden product. This confusion is confusing. Who's on first?
|
Top
|
|
|
|
#143062 - 08/06/08 07:33 PM
Re: Brunton compasses
[Re: Schwert]
|
Old Hand
Registered: 03/13/02
Posts: 905
Loc: Seattle, Washington
|
This closer look at the Dakar may reveal why it does not have any baseplate meridian lines..... I think this looks like a compass card rather than a needle. The capsule may not turn to allow alignment with the grid.
|
Top
|
|
|
|
#143064 - 08/06/08 07:47 PM
Re: Brunton compasses
[Re: thseng]
|
Sheriff
Pooh-Bah
Registered: 10/12/07
Posts: 1804
Loc: Southern California
|
A GI lensatic compass would be great ... if only it had a declination adjustment. I wonder why the army (etc.) doesn't have a declination adjustment? I would venture that even grunts are capable of adding and subtracting. lol! Well, FYI, I'v studied Algebra, Geometry, Trigonometry, and Calculus, and I still think adding and subtracting declination is a pain in the butt. Just kidding, but how would you implement declination adjustment in a rotating card compass used in the sighting mode? With the Dakar it looks like you rotate the lubber line on the face plate, but this would introduce a parallax error when not looking down from directly above. That's a very good point. Hmm. Not so easy; maybe that's why it hasn't been done. It would be interesting to hear a solid report on the Dakar in terms of it's accuracy inasmuch as it is a lensatic compass and has a declination adjustment. I hear what you're saying about the potential parallax error. One more argument against declination adjustment - if you make a conversion error while using a compass without adjustment, one bearing will be wrong. If you make a mistake setting the declination on your adjustable compass, all your bearings will be wrong. Excellent point. For what I do here in S. California, the whole area is basically 13' declination (easterly IIRC). I set the compass at home under no stress in ideal conditions with all the time in the world, and then I don't touch it again unless I travel out of state, but even for travel out of state, I set it at home before I leave. The chances of getting it wrong are pretty slim. Also, one could check the azimuth on the map from a known point to a known point (say at a trailhead to an obvious point) and compare the map azimuth with the compass azimuth. If they don't jibe with one another, it's time to carefully check your procedures and settings. I also usually carry a non adjustable back up compass. One can look at the two, compare them with the declination diagram on one's topo map and pretty quickly determine whether the compass is set correctly. In North to the Pole, the author writes how they travelled South instead of North for an entire day because he set the declination wrong. Yeah, if you're in relatively featureless terrain in the Far North (where the declination is going to shift frequently and dramatically), a declination adjusted compass might not be your best bet. One trick would be to have each member of your party independently set the declination on their idividual compasses and compare the results. If any discrepencies, STOP and think. I don't have any plans to travel that close to the North Pole anytime soon, so I think I'll stick with an adjustable compass for now.
|
Top
|
|
|
|
|
|
|
|
|
|
1
|
2
|
3
|
4
|
5
|
6
|
7
|
8
|
9
|
10
|
11
|
12
|
13
|
14
|
15
|
16
|
17
|
18
|
19
|
20
|
21
|
22
|
23
|
24
|
25
|
26
|
27
|
28
|
29
|
30
|
|
0 registered (),
820
Guests and
15
Spiders online. |
Key:
Admin,
Global Mod,
Mod
|
|
|