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#278559 - 01/06/16 12:51 AM Re: A new compass thread [Re: Mark_F]
Alex Offline
Old Hand

Registered: 03/01/07
Posts: 1034
Loc: -
1+2. The Meridian Pro and the rest of your "copy sources" are using a prism. That's an obvious flaw in my opinion. Copies removed the prism and all of its mechanics completely. It does not matter that it looks bullet proof (it's definitely not, as it's not a solid piece of metal, but parts held with screws, actually). Surely nothing is unbreakable, only the time it will be able to withstand abuse matters. However if it's absent - it cannot break. I didn't find obvious "low standards" my $5 was built upon. Everything works smoothly, everything is aligned, good adequate materials used. If you've got a defective specimen - just return it and get a normal one. I'm looking at the "not impressive results" now - looks like a perfect copy to me, except that the prismatic engineering nonsense is effectively removed. What's wrong with that copy exactly what makes it less capable than the original?

3. I have explained that extensively already but again. Leveling. If the compass is not level, your measurements have an error. Are you agree with that? Yes. Have you ever tried to use a disk compass? Not just a classic needle one? They are different in handling. Looking from the top at the disk you cannot immediately say if it's perfectly level or not. 10 deg angle and you are off by 2 degrees (and that's if your disc has no significant buoyancy). There is no problem centering the bubble first and then taking a quick bearing looking from the top. Compared to guessing if it's level or not. But that's a bad method with such an advanced compass - just look through the eyepiece and at your target, you will be able to do all that at once - target, level, measure. A dozen of tricky skills polished with years of use of classic or even mirror compass are not needed anymore.

4. I have used the prismatic compass of the same kind many years ago, it was larger, but the same principle. So the images you provided tell me enough to judge. Construction flaws have nothing to do with the manufacturing quality. They are the drawbacks of that particular engineering design. The ideal engineering design is when you obtain a feature without adding a separate feature. Simple examples of the ideal design: a half serrated knife; a firesteel with a lanyard hole instead of a handle.

Quote:
Anyway, you have to ask yourself what you're actually trying to achieve with a compass. Basic land navigation? Orienteering? Drawing maps? Surveying? Horses for courses, each task calls for a specific type of equipment.

So, I must carry 5 different compasses @20-50 each, and a theodolite with a tripod on a trail? Merchandisers will love you! Sure thing, I'll take an universal device capable of many functions from a single package instead, adding only a bulk of knowledge how to use it for any of these tasks and limitations to expect (plus my Smart Phone, to keep that knowledge sharp at hand).

Chinese nonames are getting better with every day to come. That's actually should be obvious if you just think about the long term life cycle of the outsourced US (and the world's) manufacturing. When the Automatic Assembly Line (AAL) installed, lets say, in China is at the end of its life span, Mass production brands would just invest some small amount of their multi-billion revenue to order a new AAL (the other option - they can replace failing AAL's stages to a new ones), often switching to a new version of the product as well (e.g. a drastic change to a mould shape or a press form configuration could be cheaper if done from scratch along with the new process stage integration instead of modifying the old stage). But what then happen to the old AAL or/and its semi-functioning components? Right, they became an asset off some noname but very smart and highly entrepreneurial China businessmen. They buy them cheap, fix, modify, reassemble in their own AAL (nobody else but USA, EU, and Japan manufacture and service true AALs and components to them). So, basically there is very often no much difference in the mass produced copies of brand products other than a higher percentage of defective items passing the QC/QA (ask for a replacement), but as a compensation you can see some truly genius improvements to the old brand products sometimes and obviously an extremely competitive price (again, we are talking about simple produce such as a compass, which is nothing more than a magnetized piece of metal on a post in a box, stay away from Chinese iPhones smile ).

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#278565 - 01/06/16 01:41 AM Re: A new compass thread [Re: Alex]
hikermor Offline
Geezer in Chief
Geezer

Registered: 08/26/06
Posts: 7705
Loc: southern Cal
Wow! Lots of minutiae in compass types and variations, but it looks like all, or most, at any rate will steer you to your objective and back again, if used in anything like a proper manner.

There is another major variety we have not mentioned yet, the Suunto B-14/20 (the difference being either a plastic or aluminum housing). This instrument contains a rotating compass card and a viewing window. Observing and the compass card with both eyes open, the images are superimposed and a very accurate bearing is obtained - easily within 1/2 degree. I have worked with these primarily in cave surveying, along with a clinometer working on the same principle, and have seen surprisingly accurate results achieved.

Back when I was courting Mrs. Hikermor, I bought the aluminum version and had "To Susan with Love" engraved on the side. I am sure that compass is the reason our marriage has remained on course for a quarter century....Just another use for a good instrument.
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#278568 - 01/06/16 02:23 AM Re: A new compass thread [Re: hikermor]
Alex Offline
Old Hand

Registered: 03/01/07
Posts: 1034
Loc: -
This is a much higher class and already not just a compass but an optical device. Its major advantage is the precisely aligned collimating eyepiece. It's principle is similar to the red dot gun sight. Regardless of your head position if you see the marker it will be collinear with the compass major axis. What's very effectively removing another source of human error (alligning the front and back sights). Ideal for precise target sighting. Definitely a nice thing. I had experience with the similar type Sight Master (iirc), works great but extremely sensitive, a tripod mount would be a great addition. However, they are obviously having a limited use in the mountains, as you cannot extend a collimated sight far from the dial (optics limitation), nor tilt it far enough.

By the way, I love my scuba diving Suunto compass. As in a whatever awkward position you are - it will show you the horizon level and the azimuth (it has a weighted ball like dial). But surely it's way too enormous for a land use.

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#278569 - 01/06/16 02:29 AM Re: A new compass thread [Re: hikermor]
Russ Offline
Geezer

Registered: 06/02/06
Posts: 5357
Loc: SOCAL
KB-14 looks like a decent compass.

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#278586 - 01/06/16 06:14 PM Re: A new compass thread [Re: Mark_F]
Tom_L Offline
Addict

Registered: 03/19/07
Posts: 690
Yes, the Suunto KB-14 is a very good compass if you're looking for maximum precision. To be fair, it has not really been designed as a general purpose hiking compass and tends to be impractical if working directly with a map.

For anyone interested in a direct comparison between various types of precision compasses I would recommend the following link:
http://www.itinorient-madrid.com/precision_compasses.php

I find the above comparison quite useful all in all. Obviously, some of the opinions regarding the handling qualities of a particular compass model are subjective, but the overall analysis is sound and the tables give a pretty good idea as to what kind of inherent accuracy may be expected from a given compass type.

Note BTW that the comparison includes the infamous "Wilkie" copy, which has been the subject of much debate earlier.

Also, I noticed there has been some confusion as to how the compass needle deviation is measured. The deviation error is usually expressed in +/- degrees, for instance, a compass may be said to have an accuracy of +/- 2 degrees.

However, that does NOT translate into a 4 degree error - it simply means that the maximum inherent deviation of the compass needle may be up to 2 degrees maximum from the mean (correct or spot on) reading.

Most precision compasses can achieve an inherent accuracy of well under +/- 1 degree under perfect conditions. The actual performance in the field is invariably going to be worse due to parallax, tilting and various other user errors. Still, like Aksar pointed out, a field accuracy of +/- 2 degrees is totally realistic with a good hand-held compass fitted with some sort of sighting aid.

A low-quality compass is a different story, especially if let down by poor damping and/or the absence of a good sapphire bearing that ensures smooth needle movement. This is really what separates quality compasses from inferior knock-offs - not the lack of extra features, but simply basic construction weaknesses.

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#278594 - 01/06/16 08:04 PM Re: A new compass thread [Re: Tom_L]
Alex Offline
Old Hand

Registered: 03/01/07
Posts: 1034
Loc: -
Good reading, but... For the "Wilkie" copy, the guy simply didn't realize that the disk itself IS a leveling aid. Also the hairline need to be properly focused first to see the target and the readings simultaneously, that's different from KB-14 he's carrying. It looks like the same principle, but it is not, as you should not bring the eyepiece too close to the eye as required with KB-14, that will create several possibilities to introduce errors.

I'll definitely check the drag (caused by the friction) of mine, however the seller claims it indeed has the sapphire bearing. Also you should never assume it is 0 deg, no matter how "professional" your compass might claim to be, there is no such thing as "zero friction" in physics. You should always pay attention to the needle behavior. A 3 deg drag would be obvious to a naked eye, but I didn't notice anything that bad yet. Also he seem to assume it's 0 for all other compasses reviewed, except the 2 copies on the list (prejudice?).

His "parallax error" is exactly what's caused by the misaligned needle pivot and the dial. On mine it is tested 0. So he's either got a lemon or measured it wrong (e.g. the drag/friction effect could introduce that error being partially compensated by his measurements method). In fact, all you need to amend the drag, when you want the best accuracy, - bring a small ferrous thing to the compass from one side, remove, measure A1, bring it from the opposite side, remove, measure A2, then average the two A=(A1+A2)/2 - good to know trick if you stuck with a really bad compass (typical tech.for non liquid filled compasses of the past, as they were prone to rusting, but in most cases it was possible to disassemble them and polish the post's tip). By the way, a tripod mount will help here a lot again (also by the way: KB-14 has it wink ).

Oh, and I found the Sight Master, which I've been using, on the list, it's Silva SightMaster. It has a ruler on the side, aiding with the map work. It's strange that the KB-14 seem to have no such a simple to introduce feature (the guy's saying - it's not suitable for a map work). If not a ruler, just a parallel to the sighting line edge would suffice. Could be the specific way KB-14 is calibrated at the factory, though.

So, I would take these "tests" with a grain of salt, as his testing techniques, time of testing, and the subject compasses' history are unknown variables. Nice colorful diagrams are not a sufficient reason to take an action on this data smile

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#278611 - 01/07/16 05:39 PM Re: A new compass thread [Re: Mark_F]
Mark_F Offline
Old Hand

Registered: 06/24/09
Posts: 714
Loc: Kentucky
Got an unexpected package yesterday, looks like my sister sent DS's christmas gift so he could have it for this weekend's camp out. And guess what the gift is? Yes, a brand spanking new compass, a Suunto M3 (not sure which version I didn't look that closely at it but looks much more robust than what we've been using).

Looks like DS will have a very nice compass for the weekend and I'll get an upgrade too, from a busted compass that the fluid leaked out of to DS's old compass.
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#278683 - 01/09/16 03:20 PM Re: A new compass thread [Re: Mark_F]
KenK Offline
"Be Prepared"
Pooh-Bah

Registered: 06/26/04
Posts: 2208
Loc: NE Wisconsin
Congratulations Mark! I really like my M3.

I haven't been looking around for a while, but a while back my favorite how-to-use-a-compass site was this one:

http://www.compassdude.com/

With so few visual landmarks around here (in the midwest) the GPS and compass bearings are important.

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#278760 - 01/12/16 06:15 PM Re: A new compass thread [Re: KenK]
Mark_F Offline
Old Hand

Registered: 06/24/09
Posts: 714
Loc: Kentucky
well, DS got the Suunto M3, I just got his old crappy compass lol

our scouts got a bit of a lesson in taking precise compass readings this past weekend with our scout vs wild campout. The boys's scenario was they had boarded two planes, both then crashed, plane 1 was without injury, plane 2 had victims. Plane 2 had sent their location before crashing, so the groups in plane 1 had to first find their location on the map, then find the bearing to plane 2 crash site, and make their way there to "rescue" the victims.

While it all didn't quite go as planned (the boys were supposed to have time to return to base camp with their crash victims and then have time to find compass bearings to caches of food and other supplies before lunch, as it turned out it took them til about 2 oclock to get to their victims, perform first aid, and then mae it back to base camp) it was a fun weekend and provided the leaders the opportunity to see where the boys need to be guided for further training (namely map and compass and first aid lol). ALl in all a good experience for all of us.
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#278770 - 01/12/16 09:37 PM Re: A new compass thread [Re: Mark_F]
AKSAR Offline
Veteran

Registered: 08/31/11
Posts: 1233
Loc: Alaska
Mark_F:

Scenario bases exercises are always fun and revealing. Good on you for providing your scouts this kind of learning opportunity!
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-Dorothy, in The Wizard of Oz

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