Dew Heaters - Where do they go?

[russp]

Ok.. feel like a right idiot asking this but Mr Google hasn't helped and I want to make sure  .. I know I need them - 127mm Triplet Refractor with carbon tube for astro photography .. I know I need one around the lens at the end of the scope just behind the dew shield wrapping the lens position - or at least logically I assume this is the optimal position but nowhere can I find any information / recommendations.  I'll need one in the same place on the metal tubed 80mm guide scope but is that all I need - 1 per scope given that there is no eyepiece just a camera? Or do I need more? and if so where ?

 

[Physopto]

I put one on the tube just before the CCD. This helps stop condensation on the CCD window. It does not always happen but in some camera scope combinations it can not only dew up, but you can get an ice formation on the CCD window when it is cooled. Then there is the filters you may be using to consider as well. Another reason for this is you may also have a field flattener and reducer at that position which can dew up. 

 The finder scope can be capped at both ends and only uncapped when needed. But most people probably use dew control. I use a figure of eight wrap. It is a longer dew band fitted in that configuration as smaller dew bands are not always easiest to fit. Plus one dew band will cover the whole finder scope. 

Most is down to common sense and experience. Try and see what you require. Dew bands are not cheap for quality types. Dew control can also be expensive. 

Derek

[skywatcher58gb]

Hi russup

That right you just need the two, I have an ED80 and an 80mm ST for guiding. I put one on each scope just where the dew shield fits onto the scope body. What you will also need is dew heater controller, either a two or four channel unit which you can regulate the power to the heaters.

Dave