Dew Heater Questions

[Thalestris24]

Hi all

I was just pondering over a problem and it doesn't really involve dew as such! I have a 115mm triplet apo and it's great, but... It is a pain to get temperature stabilised and the focus seems to drift until it is stable. I'm wondering weather using, say, a flexible dew heater, might be helpful in this respect. I should mention that I image through my living room window so this time of the year there can be quite a temperature difference between inside and outside. Obviously I have the heating off and window wide open. So I was looking at the Astrozap flexi-heat dew shields though they don't seem aimed at refractors but I'm thinking I want to get an even heating around the lenses. Might this work - or be a waste of time?

Louise

[Thalestris24]

Anyone got any relevant wisdom to share? I've ordered a dew heater band so will just try it out...

[spillage]

Are you able to leave it outside for a while before you start using it, or possibly leaving it in another room with the window open (like the bathroom).

Spill.

[Thalestris24]

Hi Spill

Thanks for the reply! I'd given up on this one! Unfortunately, living in a 2nd floor flat puts severe limitations on what I can do. Even letting the room cool doesn't really help a lot with the lens (but helps with thermals) and I like to keep everything set up and ready to go. Anyway, I got a dew heater band and I'm trying it out. When fitted, it's slightly warm to the touch at room temperature. I don't know quite what effect it might have especially as the scope has a dew shield and the dew heater is fitted around that. I've never had any actual dew on any of my scopes from indoors - not surprising! Not sure if I'm going to get any clear patches tonight but if I do, I'll be trying out the heater. I'll post the outcome.

Louise

[Thalestris24]

Well, it seemed to work ok... Unfortunately, I only got one sub of the Flaming Star neb and my camera died (again!). It's clouded over since so no real test yet. Looks like I'll have to get a qhy163m after all...

[newbie alert]

I seem to remember you image from a window if your flat..

You will get temperature  shift if it was outside..but being inside I think it be a lot more distinctive..the thermal inside the tube has the reach equilibrium so don't think it has to be cold..think the problem will be a warmish temp inside with a cold air temp on the lense and front of the tube..not sure what you can do about that

[Thalestris24]

1 hour ago, newbie alert said:

I seem to remember you image from a window if your flat..

You will get temperature  shift if it was outside..but being inside I think it be a lot more distinctive..the thermal inside the tube has the reach equilibrium so don't think it has to be cold..think the problem will be a warmish temp inside with a cold air temp on the lense and front of the tube..not sure what you can do about that

Yeah, I know. It isn't a massive problem and the dew heater may have helped (all a bit uncertain..) but I was getting thermals later and which weren't there earlier. I just connected the dew heater direct to the power but maybe I'll need to add a controller to limit the heat and stop the thermals. None of the scope is actually outside but, yeah, there will always be a temperature differential. Of course, I didn't have any problems when imaged with just a lens or the 130pds. The triplet will probably always be problematic in the winter.

Louise

[newbie alert]

3 minutes ago, Thalestris24 said:

Yeah, I know. It isn't a massive problem and the dew heater may have helped (all a bit uncertain..) but I was getting thermals later and which weren't there earlier. I just connected the dew heater direct to the power but maybe I'll need to add a controller to limit the heat and stop the thermals. None of the scope is actually outside but, yeah, there will always be a temperature differential. Of course, I didn't have any problems when imaged with just a lens or the 130pds. The triplet will probably always be problematic in the winter.

Louise

Other than a more than average check on focus not sure what else you can do

[Thalestris24]

1 hour ago, newbie alert said:

Other than a more than average check on focus not sure what else you can do

Might get an autofocusser for it - if one's available. Mind you, it's very difficult focussing from here - never sharp