Few heater for a 102mm frac help

[jnc71106]

Hi all

Anyone know what size dew heater I would need for a 102mm frac

I've never used one before. Do I get a 4" one as that is the size of the lens or do I get a 5" to give me some room to play

Plus where exactly do they go as the scope has a retractable dew shield

Do they go on the tube just behind the dew shield or do they go at the base of the dew shield ?

Cheers

Jake

[MjrTom]

I use a 5 inch astrozap dew strip with my 102mm refractor.

It depends on the diameter of the optical tube/dew shield.

[jnc71106]

The diameter of the dew shield is 5" the OTA is slightly smaller

Do they go on the dew shield ??

Does it matter if the heater tape is longer than what's needed

Jake

[MjrTom]

It depends on where the lens cell is located but typically yes it would be around the bottom of the dew shield when it is extended.

I cant see any issue with it being a little bit longer than the circumference of the dew shield.