SX100IS - an ISO question

[lensmen]

I have been shotting at "P" these days, set the ISO at 80.

But when taking night shots, the ISO jumped from 80 to like 800 with the up arrow point.

Could not overrule it.

How do leh ?

Help appreciated.

Thanks

[Bamamike]

In "P" the auto ISO setting is default, even setting it to 80 it will change due low light situations. Go with the "M" setting and choose all your camera setting manually.

[lensmen]

Oh great. A very intelligent Digic III ...

Does this Auto ISO applies to Av, TV settings as well ?

Also realised that my NiMh rechargeable are draining faster than my A620. Suspected that it was due to the cold weather (-3degC to 4degC). BUT I saw something at the bottom of the camera, 3.15V.

If my humble understanding goes, it means that SX100 would need a reasonable operating power source rated at 3.15V. Opps.

Why ?

My NiHm delivers 1.2V x2 = 2.4V, Alkaline (Duracell etc) delivers 1.5V x 2 = 3V. So I am underpowering my powershot, resulting in short battery life ?

Does not make sense to me....

[Jon]

The ISO you set will (should) stay after turning the camera off unless you've also enabled (a default setting) Auto ISO Shift (p. 111 in your manual).

The power rating on the camera refers to the AC adapter/external power supply input; internally, since Canon specifies either NiMH or alkaline batteries, either should work. Your SX100 has more power-hungry components than your A620, hence the increased drain.

[_aravena]

It shouldn't change. In P you still have control over a lot.Def check what Jon says.

[lensmen]

Great, found the menu on the camera for this issue.

It is definately correct and helpful.

Admitted that I was too lazy to finish reading the manual. :-)