Where to put a dew heater?

[hms_furious]

I have a 127 mak and I am getting ready for the dew season. I was thinking a heater may be better than the passive shield and I saw someone mention one of these in an earlier thread.

https://www.amazon.co.uk/COOWOO-Temperature-Regulator-Universal-Telescopic/dp/B07MHGW4DG/ref=sr_1_3?dchild=1&keywords=coowoo+dew&qid=1597740390&sr=8-3

I know it is a little shorter than the circumference of a 127 but a  a couple of bits of heavy duty velcro should fix that.

Two questions

1) is a dew heater all you need?

2) where should it be located on the scope? I have seen it about 6 or so inches away from the front lens.

Anything else I should consider?

Thanks again all

[Tomatobro]

This is a personal view but I hate spending the same money twice. An Astrozap heated extended dew shield from Flo will work first time and every time. Yes its double the cost but it has a zero risk attached. The corrector on the front of the Mak is very prone to dewing so the alternative might but there again might not be enough for extended viewing sessions.

[hms_furious]

18 minutes ago, Tomatobro said:

This is a personal view but I hate spending the same money twice. An Astrozap heated extended dew shield from Flo will work first time and every time. Yes its double the cost but it has a zero risk attached. The corrector on the front of the Mak is very prone to dewing so the alternative might but there again might not be enough for extended viewing sessions.

That's true but then don't you also need a power supply (you can use a USB power bank with the coowoo) and then also need a heat controller for it too which adds more to the price?

[jonathan]

Before buying a dew heater setup I would try just a dew shield, it might be enough for most nights on a 5" Mak.  Key is to try not to expose the front glass element to the sky, the dew shield will retain some warm air in front of the glass but keep it pointing towards the zenith for any length of time and Woomph!  The warm air is gone, in comes the dew.  You can add dew heater tapes or replace the dew shield with a combo one as mentioned earlier in this thread if the dew shield is not enough, just don't expect either or both to eliminate dew every time.

On my 8" SCT I place the dew heater tape right behind the front plastic rim, it needs to be as close to the front glass as possible so that it can spread some warmth onto the glass.  You do not want it at the bottom end as this will lilkely send warm air currents up the tube and result in turbulence.

Edited August 18, 2020 by jonathan

[Tomatobro]

I don't use controllers. Experience tells me when dewing is likely and mostly its left plugged in but if the risk is low I just unplug

[Cosmic Geoff]

Try a dew shield without the dew heater. It is essential to use a shield with a Mak or SCT in conditions where there is any chance of dewing up.  In my location I have found the dew shield to be sufficient 99% of the time (no heater).  Trying a heater tape without the shield would be unconventional, I think.

You do not have to spend money on a shield. The bought ones look smart, but I made mine from cardboard as nobody else ever sees them operating and I don't care what they look like.

Edited August 18, 2020 by Cosmic Geoff