etx125 (very) Cold weather

[EssexMigrant]

Hi Folks,

Apart from introduction, this is my first post. I will shortly be using for the first time my ETX125. Are there problems associated with using this type of scope in sub-zero situations please?

Max

[brianb]

BATTERIES - really hate the cold. Suggest using an external power supply (high capacity power tank) if at all possible.

You'll need a dew shield but this is nothing new.

A sock to keep the handset in when not in use will help. The display may dim or update very slowly in cold weather but it should work OK in any temp you're likely to meet in the UK.

[EssexMigrant]

Hi Brian,

Thanks for your quick reply. So I don't need a heating strip or such like?

Max

[brianb]

I don't need a heating strip

Not for low temps. If the condensation is bad enough to cause the objective to mist over despite the dew cap, a heater strip will be useful ... but it's to keep the corrector plate from overcooling rather than because the temps are low.

This arctic air mass we've got at the moment is actually pretty dry (except in the troughs where snowfall is occurring) condensation is not much of a problem, the snow here thinned by half an inch or so - by evaporation - overnight despite temps down to -6C.

[EssexMigrant]

Not for low temps. If the condensation is bad enough to cause the objective to mist over despite the dew cap, a heater strip will be useful ... but it's to keep the corrector plate from overcooling rather than because the temps are low.

This arctic air mass we've got at the moment is actually pretty dry (except in the troughs where snowfall is occurring) condensation is not much of a problem, the snow here thinned by half an inch or so - by evaporation - overnight despite temps down to -6C.

Hi again Brian!

This is very helpful info. On a related point, how does dew point relate to humidity? For instance, at this moment my phone tells me that dew point is -5C and humidity is 74.20% with an air pressure of 745.60mm. I've just had a look at where you live (nice situation; lucky man) and it's clearly very different to mine. I'm nearer to the Wash; North Sea whereas you're close to the Gulf Stream.

Max

[brianb]

how does dew point relate to humidity?

As temperature of unsaturated air falls, the humidity increases and eventually the air becomes saturated. When the air is saturated, mositure will condense onto any surface available. Dew point is the temperature at which the air becomes saturated (humidity 100%).

[EssexMigrant]

As temperature of unsaturated air falls, the humidity increases and eventually the air becomes saturated. When the air is saturated, mositure will condense onto any surface available. Dew point is the temperature at which the air becomes saturated (humidity 100%).

Very many thanks Brian, I had a feeling you'd know the answer!

All the best

Max