F5 Barometer settings

I can't comment on the F5 as yet.
The F3 is permanently in auto mode. Mostly where people see that not working, it is failing spectactularly. In an F3 I'd suspect a hardware fault; in the F3HR, Garmin appear to have acknowledged that there's a firmware fault that is causing crazy behaviour, and promised a fix at some point.
I last calibrated my F3 on Sunday, at which point sea level pressure was 996mB. Since then it has gone up and down, peaking at 1032mB and falling to 1020 now. (I have a pressure sensitive instrument at work which logs that daily, among other things, so had the values to hand). The F3 thinks it is at 13m when it is in fact more like 20m, which I think is pretty good. If I left it at home, I'd expect it to be tighter, because if the accelerometer feels no vibration it assumes all changes must be weather-related. I very rarely leave it at home, though.

It has a couple of calibrations by location stored, from the places I most often start cycles or runs (that is home and work). Other than that I don't often bother calibrating it, unless I've travelled a long way - train journeys can throw it off, especially as slow elevation changes with little vibration can register as weather changes. Last time I travelled to my parents' home by train, it was accurate when I set out and about 5m out when I arrived, which again isn't bad under the circumstances.

It might be worth waiting to see what initial buyers think. It would be a shame if the F3 bug persisted into the F5 line.

So if you leave it at home, the altimeter does not change, regardless of any pressure changes?

So if you leave it at home, the altimeter does not change, regardless of any pressure changes?

For the fenix 3/tactix Bravo that is correct:





When the watch remains at the same Elevation, the recorded Elevation remains constant despite chaging Baro pressure.

HTH

So if you leave it at home, the altimeter does not change, regardless of any pressure changes?

Conversely, in the presence of constant Baro pressure, Baro pressure remains steady despite changing Elevation:





HTH

Well this last one confused me
How can the barometer be steady and the altimeter changing?
This is a barometric altimeter, right?
Altitude changes are calculated based on pressure change
I assume GPS is not affecting the altitude when in house (poor or no reception)

This last one confused me
How can the barometer stay constant, but the altimeter change?
This is a barometric altimeter, so the pressure determines the pressure not the other way round.
That is if the GPS is not doing anything, but I assume that the GPS would not affect the altitude when in house (poor reception etc)

This last one confused me
How can the barometer stay constant, but the altimeter change?
This is a barometric altimeter, so the pressure determines the pressure not the other way round.
That is if the GPS is not doing anything, but I assume that the GPS would not affect the altitude when in house (poor reception etc)

The reported/displayed Baro pressure is adjusted to MSL (Mean Sea Level) pressure. This is the way airports (METAR) and weather stations report Baro pressure. Some other watches - Casio in particular - report pressure as Absolute pressure. Absolute pressure is simply the air pressure at the sensor without any adjustment to MSL.

If a watch reports Absolute pressure, then your statement is correct - reported/displayed pressure will necessarily change with changes in Elevation.

If a watch reports Baro pressure adjusted to MSL, like the fenix 3/tactix Bravo watches, then the reported/displayed Baro pressure will remain constant with changes in Elevation (assuming the prevailing weather pattern is, indeed, one of constant pressure).

The GPS Altimeter Auto Calibration function found in the fenix 3/tactix Bravo watches is an entirely different question which is made more difficult to address simply because it does not function as described in the Owner's Manual.

HTH

Edit to add:

Just to be clear, the onboard pressure sensor in the fenix 3/tactix Bravo watches measures absolute pressure to determine Elevation then calculates what that pressure would be if the Elevation were Mean Sea Level and reports/displays that. So yes, as Elevation changes, Absolute pressure does change, but the reported Baro Pressure will not because it is adjusted to MSL.

In GAIJIN's second set of photos he's been moving sufficiently for the watch to switch to attributing pressure changes to changes in altitude rather than to weather changes. So, if you stay still the Fenix 3 attributes pressure changes to barometric pressure changes due to weather, but if you are moving around sufficiently then the Fenix 3 assumes pressure changes are due to change in altitude only. From the user manual, it looks like the Fenix 5 is adding the option to have things like they are on the Fenix 3 (Auto) or to manually choose to lock the pressure change attribution to either altitude (Altitude) or ambient barometric pressure (Barmeter).

I hope that makes sense now.

So if you leave it at home, the altimeter does not change, regardless of any pressure changes?

As Gaijin says, yes.

In that case, I am curious what this Auto feature does in the F5

Same as the F3, most likely. The difference is that the F5 has explicit Altimeter and Barometer modes, too, which let you ascribe pressure changes only to one or the other. I can see the first being useful if you know the sea-level pressure is going to be pretty constant throughout your workout. I can't see when the Barometer mode would be useful, unless you're leaving the watch in one place for some time and want to be absolutely sure it doesn't wander in elevation. The F3 used to have more modes, but they ended up simplifying it to the current one.