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How necessary is the sighting mirror on a compass?

Looking for a new reliable compass. I have looked through the REI basics and looked at its article on how to buy a compass. 

I just want a compass that is reliable, has all the basic features, glows in the dark, and is NOT a global compass. I am also trying not to spend an extra $20 on a compass just for the sighting mirror?

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Re: How necessary is the sighting mirror on a compass?

If you are only carrying a compass as a backup,  the mirror is unnecessary.   It will just add weight and make the compass more fragile.

If you are actually interested in navigating using a compass then having one with a mirror is very helpful.

The sighting mirror makes it much easier to taking bearings and also generally gives you a clinometer feature allowing you to estimate the steepness of a slope.

The mirror also makes a useful vanity and emergency signalling mirror.

But the most useful feature to pay for is adjustable declination.  You do have to remember to set the declination correctly for your current location but once set it avoids you having to calculate the true bearing by manually adding or subtraction the declination...an error prone activity. 

Also when buying a compass make sure to get one for the the hemisphere you intend to use it in.  There are some more expensive models that work in both the northern and southern hemisphere but mostly they are designed to work in one or the other.

Another consideration is what maps you will be using since the grid on the plate of the compass generally comes in one of two varieties... USGS (1:24,000) with inch scales for the US and Metric (1:50,000) with mm scales for everywhere else.  Recreational maps are often slight odd scales so this may not matter as much to you .

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Re: How necessary is the sighting mirror on a compass?

Well, you should have a mirror of some sort in your gear.  One comes in handy in various ways, most particularly when used as a signal mirror, but also to direct sunlight into dark spaces, and various other uses.  A compass is a good place to keep one and it comes in handy also in navigation in various situations.

I believe you can buy a dedicated signal mirror for less than $20, if the cost is important.  Actually, if I had to choose, I would carry a signal mirror and leave the compass behind and hope for good weather.  But I always carry both.

Actually, the most important aspect of a compass is reliability - a feature worth paying for, because if you need to use your compass, most likely you will need to trust it completely and that can get 'interesting" very quickly.

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Re: How necessary is the sighting mirror on a compass?

Typically, one uses a compass with mirror for truer azimuth reading over distances while orienteering with a compass. It aids in capturing the definitive azimuth if sighting to peaks far off in the distance. Only ‘you’, know what type of accuracy you’re seeking. I personally opt for lighter, less costly model without a mirror when hiking trails in parks and using maps moderately.  I go to mirrored model when that map and compass are my sole navigational materials by which to designate a path through wilderness areas less traveled or the trail isn’t well marked. Hope that helps a bit! Safe Travels! {Jim E. from REI Northbrook, IL}

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Re: How necessary is the sighting mirror on a compass?

I've never needed it or used it and wouldn't pay extra for it.

REI Member Since 1979 YouTube.com/philreedshikes
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Re: How necessary is the sighting mirror on a compass?

Ahh...Different strokes for different folks.  Don't venture out lacking a sighting mirror on your compass or you will surely die!!

Actually, I go for years without pulling out my compass, going entirely by terrain association, which works quite well in the bumpy terrain I frequent.  Reduced visibility due to fog, etc. will get me looking at the compass.  i can recall only one occasion where  I navigated with a compass in good visibility.

Things are quite different when at sea, however,where objectives my be out of sight or obscured by fog.  I am constantly on the compass then.

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Re: How necessary is the sighting mirror on a compass?

OK.  My .02

I like the mirror. It's useful as an accuracy aid with the compass - especially if you have known fixed points like summits or the like for orienting your map. It takes some practice, but the practice can be fun.

Then it's also useful for other things like checking your eye for foreign objects (and, I suppose, signaling, though I have never done that).

So, you don't HAVE to have one. I just like it.

One weird thing I found out the hard way , is that you can ruin a good compass by keeping it with your cell phone. True story: I actually ruined a nice Sylva this way. The needle just floats around without any conviction about magnetic north.

“But I reckon I got to light out for the Territory ahead of the rest, because Aunt Sally she's going to adopt me and sivilize me, and I can't stand it. I been there before.”― Mark Twain, The Adventures of Huck Finn
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Re: How necessary is the sighting mirror on a compass?

There are several ways a compass can point askew besides cellphone proximity.  Any kind of magnetic material (large chunks of iron or steel) on or about your compass or even magnetic material in surrounding rocks can give an inaccurate reading.  This happened to us on Orizaba some years ago.

Learn alternative ways of finding North - learn the night sky and where the north star (or southern cross, if you are down under) is located, for instance.

That Orizaba trip, many years ago, was one where a lady in our party needed suitable boots quickly.  her boyfriend, a member of REI, put a check in the mail (this was before credit cards) while REI put the boots in the mail at the same time.  They arrived promptly, leading to successful ascents.

I believe his membership number was about 9000.....

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Re: How necessary is the sighting mirror on a compass?

If you are only carrying a compass as a backup,  the mirror is unnecessary.   It will just add weight and make the compass more fragile.

If you are actually interested in navigating using a compass then having one with a mirror is very helpful.

The sighting mirror makes it much easier to taking bearings and also generally gives you a clinometer feature allowing you to estimate the steepness of a slope.

The mirror also makes a useful vanity and emergency signalling mirror.

But the most useful feature to pay for is adjustable declination.  You do have to remember to set the declination correctly for your current location but once set it avoids you having to calculate the true bearing by manually adding or subtraction the declination...an error prone activity. 

Also when buying a compass make sure to get one for the the hemisphere you intend to use it in.  There are some more expensive models that work in both the northern and southern hemisphere but mostly they are designed to work in one or the other.

Another consideration is what maps you will be using since the grid on the plate of the compass generally comes in one of two varieties... USGS (1:24,000) with inch scales for the US and Metric (1:50,000) with mm scales for everywhere else.  Recreational maps are often slight odd scales so this may not matter as much to you .

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