Dew straps needed?

[gonzostar]

I have a new ES 102mm ED APO refractor mainly intended for imaging. 

Do i need dew straps for this scope or is the dew shield suffice? 

Cheers 

Dean

[DaveS]

Yes you do, though as the nights get warmer (Ha ha) the risk of dewing will decrease. I've had to repeatedly use a hair dryer on lowest setting to de-dew the objectives on both the 130 and 80mm 'scopes (And lost subs) until I bit the bullet and stumped up for dew control.

For the 130 I put two dew bands on, one on the dew shield and another just below the lens cell.

[gonzostar]

Thanks for your reply. I have read around and seems to be lots of conflicting advice about refractors. I will use a dew strap i now my SCT collected dew for fun! 

Lets hope the nights are getting warmer too!  

[wimvb]

I made a 30 cm long dew shield from a rubber foam mat, for my guide scope. I have found that this is enough to keep dew from the optics. A selfmade dew strip alone wasn't up to the job.

The dew shield that comes with the scope isn't enough, but a longer shield may be more efficient than a heater. It depends very much on how much moisture you have in the air.

 

[gonzostar]

I seem to get alot of dew in back garden. Lots of green stuff around  Hopefully the refractor wont be as bad as  the SCT!