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Towsey

Please help

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Hi all

 

I bought a kestrel 4000 the other day, I was looking for a 3500 really but this nearly new 4000 came along a lot cheaper, anyway...

 

I'm after a bit of advice please. Am I right in thinking that when I set my actual altitude and then the baro' pressure that my readings are only correct at either that set altitude or that pressure depending how I did the settings? For shooting do I not need the actual altitude and pressure of where I am at that time? Am I rite in thinking that 'station pressure' is the actual pressure of where I am, and that is found by setting my reference altitude to 0. But how, if at all possible, do I get an altitude reading of where I am???

 

Many thanks for your help

 

Towsey

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Towsey

 

I don't have a Kestrel but you have loads of options available to you.

 

I use Strelok and this has a built in altimeter.

 

There are also lots of free altitude apps available for your smartphone.

 

Hope this helps

 

Cheers

Froggy

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Towsey,there is no harm at all in having a detailed ballistic engine like the advanced kestrels;used properly they can fine tune shooting solutions (clicks). !000y shooters in US may have 5 moa differences in extremes.....

Can I just clarify what your application (shooting) is-eg competitive 1000y f class in UK;or small to 300yards mostly,in a part of the U.K. which isn't hills and valleys (US ranges can be 5000feet different and 60F degrees).

 

Atmospherics,pressure,temperature,(and very much less ,density) affect BC and velocity,and hence bullet trajectory-the issue is -how much,and how much does it matter....

( Just to orient: I was watching F1 Bahrain recently,(though any will do)-tyre temperature is clearly critical for competitive racing,but is it for the family car on a weekend outing,if the weather has changed a bit since mid week?

 

Well,here are two US scenarios :sea level 6mm BC.265 @ 3150 fpsMV:

750 feet, 30 F. Drift at 200y. 4.67 inches. (BC now .256)

5300 ". 70 F. Drift at 200. 3.55. ' (BC now .330)

 

The difference-for extremes by UK possibilities for altitude. Is 1.12 inches drift at 200y.

Maybe puts some perspective on it.meanwhile-though it does not answer your input question-do you have the Kestrel instructions?

 

(As well as Apps,ordinance survey maps give contour lines-altitude above sea level).but you may /not need rocket science. :-)

 

gbal

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Thanks for the replies people

 

I too have the altimeter on strelok and I know my base altitude, and to be honest I didn't buy this kestrel for the less needed features, and yes it came with instructions. If I'm honest getting the altitude from the kestrel when I want it is why I'm asking, it's not particularly for the purpose of shooting.

 

The instructions say that you need to use a weather website or other means to get your current altitude or pressure so you can set the reference settings, but it also says you can set reference altitude to 0 to get station pressure which is your current pressure at your current location (the thing to use for shooting)...so can you not use your station pressure as your reference pressure to set it up, and more to my original question, can a kestrel be used to give a current true altitude (il call it absolute altitude for this purpose but that's proberbly wrong ) let's say for interests sake, like you can get station pressure which is also called absolute pressure?

 

Many thanks

 

Towsey

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Towsey, if you want to use Kestrel as an altimeter-eg to give altitude(s) on a hill hike, does this help?

 

"Problem is,if you go hiking and change altitude,the barometric pressure will be off until you readjust your reference altitude.There is no way to lock in altitude tobe accurate allthe time.

That said,it can be useful.Before a hike,set the reference barometric pressure before you start,then you can track current altitude along the way. Usually,it won't be off by much on a day's hike."

 

KestrelMeters.com

"Setting the Pressure /Altitude in KestrelMeters'

Scroll to "Why does it fluctuate,and how often do I adjust it"

 

IF I am still reading you wrong,sorry-I would not go without an Ordinance Survey map anyhow,and use contour lines.

 

gbal

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What you are saying rings a bell regarding setting it to zero for pressure reading. Possibly one of the long range tutorials on youtube

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Panhandle Precision in the US have done a load of "How to use your Kestrel for long range shooting" videos, mainly talking about the 5000 series, but all aploes to the 4000 series as well with slight changes to UI.

 

 

Is a good one talking about the differences between Baro and Station Pressure.

 

Station pressure is what you need to be using for shooting.

 

Here's a guide if you want to use it for tracking altitude, for example with hiking up a mountain.

 

http://www.nkhome.com/pdfs/Kestrel_Pressure_Altimeters.pdf

 

With shooting, the atmosphere is what we are interested in, and Temperature, Humidity and Pressure all play a part in how the atmosphere is for the bullets flight. Becoming more popular these days is using a single number called Density Altitude (your Kestrel 4000 will display this).

This essentially compares your observed atmosphere to the International Standard Atmosphere (Sea Level, 15C, 1013mb), and gives you an altitude you'd be at given ISA conditions.

 

So if your density altitude is say 2000ft, on a wet hillside on the UK at 12 degrees.....your atmosphere is the same as someone who's in a desert at 30 degrees with a different station pressure, but all adding up to 2000ft DA too.

 

So density altitude is a great number to use, again, there are loads of YouTube guides on why we can use Density altitude as a single atmospheric measurement for our shooting, rather than individually putting in Pressure, Temperature and Humidity.

 

It also makes life simple, as your ballistic calculator App only requires two inputs then to function, Density Altitude and Temperture (it needs a seperate temperature measurement to work out the local speed of sound).

 

Very powerful bits of kit those Kestrels....it's top of my list of things to buy ASAP.

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Thanks again for the replies

 

I just wanted to know if my kestrel can be used to tell me my current altitude when I'm on the wolds or the moors walking the dog or off-roading, without having to be set up with known references etc, like it can be used to get my station pressure without having to input any known info (I suppose station altitude will make sense even if it's the wrong thing to call it)

 

It's not for the purposes of shooting and I am aware of the effects of conditions on shooting (although the links people have put up are very good)

 

I did not want to write my original post in this blunt manner and come across like a cocky, clever know it all, please believe this is not the case at all. I just wondered if my 4000 would give me a good altitude reading if I ever think "it's quite high here I wonder wot my altitude is". It would appear not, although I can work round it when I need to

 

Thanks again and my apologies if this post reads badly

 

Towsey

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That's correct; you'll always have to enter a barometric pressure to get a decent altitude reading, even aircraft have to do this before each takeoff/landing.

 

Best bet sadly for a quick altitude lookup is GPS altitude available on most phones with an app.

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Yeah that was the conclusion I'd come to. Il stick with the phone for doing it, I just couldn't see how good the kestrel would be for it but now I know.

 

Thanks again all

 

Towsey

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Thanks again for the replies

I just wanted to know if my kestrel can be used to tell me my current altitude when I'm on the wolds or the moors walking the dog or off-roading, without having to be set up with known references etc, like it can be used to get my station pressure without having to input any known info (I suppose station altitude will make sense even if it's the wrong thing to call it)

It's not for the purposes of shooting and I am aware of the effects of conditions on shooting (although the links people have put up are very good)

I did not want to write my original post in this blunt manner and come across like a cocky, clever know it all, please believe this is not the case at all. I just wondered if my 4000 would give me a good altitude reading if I ever think "it's quite high here I wonder wot my altitude is". It would appear not, although I can work round it when I need to

Thanks again and my apologies if this post reads badly

Towsey

Towsey, yes, you could use it like a mountaineering altimeter, but you would need to regularly reset the altitude at known points (ie points of known altitude from firm map detail.). How often you need to update the altitude from fmd would depend on your judgement of how changeable the weather is: Big weather changes (such as a front approaching) will lead to inaccurate altitude readings, and you would need to update more frequently than on, say, a calm day.

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Thanks for that

 

I know my home altitude and I'm going to get the altitude of some other places I go, then when passing these places I will set my reference altitude and go from there. I've gone all these years without my kestrel so that will have to do and it's better than nothing

 

Cheers

 

Towsey

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