Quote:
Originally Posted by cfranks
I have ordered additional dew straps to place on the tube near the mirror but it remains to be seen if that is a good idea, obviously I don't want to affect my imaging.  |
Hi Charles
This is exactly what I have on my scope (but molded into the
inside of the tube) along with a
small Kendrick heater pad on the back of my secondary mirror and I have never seen any dew on either my secondary, primary or corrector face (exposed inside tube) in 3 years of using the scope. I too was concerned that having a tube dew heater just in front of the primary mirror might affect my imaging but as you an see from the following images I don't recon it does..?
Each of the three following image was taken with the secondary heater, tube heater and rear fans (that suck the air out of the tube) going throughout the entire exposure in a
fully exposed position out in the open in Canberra.
Fornax A
NGC 253
NGC 1365
And even in the warm moist coastal air of
Newcastle, while the seeing wasn't as good as in Canberra, I
never saw any dew on the optics
Then once
inside a dome and out of the elements with the same dew prevention running, the resolution only improved
Devils Mask
200 Million light year distant cluster
And again I have not seen any dew form anywhere
So I recon if you wrap a heater strap around the outside of the tube at the level of the mirror face and install
a secondary heater pad then run your fans...all should be hunky dory
I recon you should try making a dew shield as well though - everything helps
ED: I see you already have a secondary heater - good.
Mike