Guys I just picked up exbal for the pc and a pocket pc and have a question about which data do you use when in the field. My data measurement device is a Brunton Summit ADC and the baro determines the alltitude. Do you put in the correct alltitude and the current pressure reading or the adjusted alltitude? This summer I had a chance to head to Colorado and the drop chart from home wasn't even close once I had chance to get out to 1000 to 1400 yards. My house range goes to 750 and the chart was very close to there but changed quickly after that. Thanks Dave
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ss7mm
Well-Known Member
You'll find some good reading here. It'll answer all of your questions. http://www.longrangehunting.com/forums/f19/altitude-vs-barometric-pressure-11950/
Thanks Dick, I remember being confused the first time I followed that thread and don't think it helped any more now either. Perhaps if I state it a little differently someone can clearify it for me. My home alltitude is 900 ft. My measurement device will list BP say of 28.95 but it tells me my alltitude is 915. Now the weather changes and the new readings will be lower pressure and it shows I am at a lower elevation then what I am at. So what do I enter in exbal for my sight in conditions. The BP at its currrent reading and the elevation it says I am at or the actuall elevation I know I am at. Here is what I am trying to figure out, I now what my elevation is because of a gps, I have a location reading for BP but the elevation number it states I am at may and usually is different then what I know I am at. Perhaps I need a Krestel unit I don't know but the wife aint gonna be happy after the hand held and software bill shows up. Dave
ss7mm
Well-Known Member
If you don't have the calculate std. pressure box checked, you simply enter the known barometric pressure for your current location and leave the elevation box empty.
My GPS and Kestrel never do both read the exact same elevation. I need the GPS elevation to calibrate the Kestrel and then I have the BP. If I use that BP to calibrate the elevation in the Kestrel I always end up with a little different elevation in the Kestrel than I do in the GPS.
My GPS and Kestrel never do both read the exact same elevation. I need the GPS elevation to calibrate the Kestrel and then I have the BP. If I use that BP to calibrate the elevation in the Kestrel I always end up with a little different elevation in the Kestrel than I do in the GPS.
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Dick I was just reading all the other posts again and came back and saw your reply, thank you. I think I may be on the right track but help me out. I will try to just the pressure reading to get as close to the elevation as possible and see what the program prints out. By this I mean I will enter the BP optained when I adjust it to get close to 900 feet and believe this number to be station pressure so I would uncheck calculate for corrected pressure. Now which modle of the Krestel do I need. I bellieve my unit uses air density to calcuale BP and allitude and I can't be sure it will give me Station BP. I don't have anything that gives Station Pressure and the National Weather Staion is 25 miles away and alot higher. Dave
ss7mm
Well-Known Member
Check out this link to a thread that discusses the Kestrel and has a chart for comparison.
http://www.longrangehunting.com/forums/f17/nightforce-ballistic-softwear-kestrel-do-i-need-24131/
Budman,
Once you've made sure your data istrument has been calibrated properly by following the user manual your next steps are rather simple.
Note: Also make sure your instument is giving you local, on spot readings for BP and not sea level corrected.
Now, you need to now your "on spot" elevation, GPS elevation should be close enough; enter that elevation on the data instrument and of course that will make you BP value change.
On Exbal, you enter the current "on spot" elevation and the BP given by the data instrument once the right elevation is changed into it. The box where it says "calculate std pressure" leave it unchecked unless you don't know the BP but you know the elevation then you enter the on spot elevation and check the box for the program to use the standar BP for that particular elevation. I hope that made sence.
Thanks again Dick, I managed to discover from an online Kestrel manual that my unit and most units will give station BP if you can manually set the elevation to zero. I will test mine tonight and maybe I can keep the misses happy a little longer. But it looks like the 3500 will have to get added to my gear list. Dave
Eaglet thank you also, I needed all the help I could get. I was trying to follow your post in the earlier thread put you must of had pictures in them that are no longer there but I think I have a handle on it now. Sure glad Len has this place for us to learn. I will recheck my calibration also. Dave
