Dew Prevention Advise

[Damo636]

I am thinking of buying this dew controller and wondering is it up to the task? HitecAstro Single Channel Dual Port Dew Controller | eBay

Also, the dew shield on the scope is a sliding affair and completely covers the objective cell even when retracted. I will have to attach the heat strip around it rather than the objective cell. I wonder how effective it will be using it this way? Are the dew straps designed to be used without the scopes dew shield in place?

[Herbig]

I've just ordered one of the HitecAstro Dew Controllers. They should be up to most applications for amateur use, I think they are rated at 5 amps. My C8 dew strip is only about 1.25 amps so should be scope to add another with no problem. As regards the positioning of the strip, it's best to place it round the outside of the objective lens cell or as near to it as possible either on or behind the dew shield, you may need to try both to see which works best. However heating the tube is not a good idea as this can intorduce convection currents. Use the heater on as low a power as conditions allow.

Regards

[brantuk]

You can extend the dew shield and wrap the dew tape round it at the position of the objective lens - this will work fine - but you do need both the shield and the tape

[Photosbykev]

I was out shooting the ISS this evening and dew was forming on the CF tripod in less than 10 minutes, without a dew tape around the lens I would of been wasting my time. Dew control is quickly becoming complusory lol

[RikM]

Dew crippled me last night. I have a dew shield on my Newt and most of the time it is sufficient, but my guider got fogged solid last night. Something must be done...

[Damo636]

Thanks guys, i'll have a go at wrapping the strap around the extended dew shield and directly over the objective to see how it goes. I was spoilt over the summer with very little dew but the other night was a nightmare. I had around 45minutes before it started to form.

[ollypenrice]

I use dew heater strips but not heat controllers. I just run them at full power and can't see any reason to do otherwise. I'll stand corrected of course but it works for me.

Olly

[brantuk]

It worked for me on both the ST80 and the Meg72 - with the CPC though because it's a detachable dew shield - I put the dew tape round the corrector and then attach the shield over the top of it. But it will work with your refractors for sure

[laser_jock99]

I have yet to get 'proper' dew heater strips for my scopes. Had to resort to using the wife's hair dryer again last night. It's only a solution if you have mains near the scope, but you can probably get 12V camping hair dryers somewhere?

[Damo636]

I use dew heater strips but not heat controllers. I just run them at full power and can't see any reason to do otherwise. I'll stand corrected of course but it works for me.

Olly

What brand of strips do you use Olly? I thought a controller was necessary with all these strips. It would be nice to save a few quid for a change and do without the controller if possible.

[todd8137]

never had a prob with dew at all,but brught a de shied for stray light as my neigbors sem to use the toilet alot

[ollypenrice]

What brand of strips do you use Olly? I thought a controller was necessary with all these strips. It would be nice to save a few quid for a change and do without the controller if possible.

Hi,

Mine are (American) Orion by brand. I thnk SCS Astro do Orion stuff but they probably appear in other brands as well. They just run off 12 volt.

Olly

[Charon]

Damo, have you considered the Astrozap heated flexible dew shield? I have one and it works a treat with my cpc800 (dew magnet).

[Herbig]

I have Kendrick and home made ones, yes you can run them straight from a 12v source. But I'd just check first that they don't get too hot! Most commercially available ones should be fine though. As BrantUK mentions I also run mine with a detachable shield (camping mat) over the dew strip this also helps to keep the heat in. There is no reason why you could not do this also even though you have one attached, you can also make it a bit longer. Another reason for using a dew controller is if there is no mains available at your observing site, you don't want to be using power unneccessarily, but if that's not a problem then fine.

[Damo636]

I'll probably go with an Orion Dew Zapper or the slightly cheaper Dew-Not and also extend the existing dew shield with a bit of camping mat. The Dew-Not version claims to use less power. Thanks for all the replies.