Dew

[Lee M]

Managed to get out for a couple of hours with reasonably clear skies last night. The first outing for my 200p dob. I got the scope outside whilst there was still a bit of light. So it had a good hour and a half to acclimatise.

All went fairly well. But the Telrad and I think finder scope got quite dewy. Main scope was fine apart from if I breathed too much near the EP. (Note to self - stop breathing so much!).

So a couple of questions - what do people do in that situation - wipe finders with a bit of lense tissue?

I'm guessing with the EP you just learn to breathe out in the right direction?

Lee

[gkec]

Managed to get out for a couple of hours with reasonably clear skies last night. The first outing for my 200p dob. I got the scope outside whilst there was still a bit of light. So it had a good hour and a half to acclimatise.

All went fairly well. But the Telrad and I think finder scope got quite dewy. Main scope was fine apart from if I breathed too much near the EP. (Note to self - stop breathing so much!).

So a couple of questions - what do people do in that situation - wipe finders with a bit of lense tissue?

I'm guessing with the EP you just learn to breathe out in the right direction?

Lee

Hairdryer if you have mains power. Not too hot though.

[paul mc c]

Yes quick blast of hot air,of as soon as you see the eyepiece starting to go wave your hand or piece of carbboard close to

the eyepiece,works well for me.

[VigdisVZ]

Yeah there are several ways here.

The primary on a newton rarely gets dew due to the tube acting as a dewshield, however the secondary can dew up so I always use a homemade dew shield made form a camping mat. And a telrad finder could also use a hood made from some suitable material.

If that isnt enough you can give it a blast with a hairdryer.

Eyepieces are easy to keep dew free by putting the caps on them and having them in your inner pocket.

There are also dew heaters you can attatch to strategic areas.

[Tinker1947]

I have installed a dew heater on my ST80 guide scope, it really does keep the main lens clear, the do a model for the Telrad not got round to getting one but if its any thing like the ST80 for keeping it clear, its a got to have...

[gkec]

I did try a 12V fan heater designed for demisting windscreens. Drained my power tank in seconds. Which was surprising when in a car it has only a slight effect.

[Lee M]

Fantastic. As the wife is already giving me raised eyebrows for disappearing down the garden with a telescope I'm sure the look I get I head off with her hairdryer on the end of an extension lead will be priceless :D

I'll have to look at the dew heater for the Telrad. I haven't used it in anger yet. Tomorrow hopefully.

[Lee M]

Yeah there are several ways here.

The primary on a newton rarely gets dew due to the tube acting as a dewshield, however the secondary can dew up so I always use a homemade dew shield made form a camping mat. And a telrad finder could also use a hood made from some suitable material.

Hi Vigdis

I can't quite envisage what I'd be insulating on the secondary or the Telrad. If you can point to an example that would be great. I'll have a hunt around tomorrow if not.

Cheerss

Lee

[gkec]

Fantastic. As the wife is already giving me raised eyebrows for disappearing down the garden with a telescope I'm sure the look I get I head off with her hairdryer on the end of an extension lead will be priceless :D

I'll have to look at the dew heater for the Telrad. I haven't used it in anger yet. Tomorrow hopefully.

You can always buy your own.!

[Lee M]

You can always buy your own.!

It wouldn't get a lot of use other than for demisting kit. Not a lot of going on.

[jason.p]

I keep my EPs warm in bubble wrap envelopes in my pockets (have to remember which pocket has which one) A bulb blower can work as well. I've made the Telrad dew shield, but in heavy dews like the last few times it still mists up. I've now got an old hairdrier, set on cool, a quick blast is very effective especially when it starts to freeze.

[Astro Imp]

As far as the Telrad is concerned a light wipe with a tissue isn't going to do any harm as the glass is not an optical surface but a dew shield of some kind certainly helps but won't keep it completely clear. Telrads really do seem to attract the dew.

[Lee M]

Cheers all for the comments.

I found this:

http://www.homebuiltastronomy.com/downbino/HomeBuiltAstronomy-TelradDewShield.html

which shows a simple dew shield for the Telrad. Just in case it helps anyone else.

Lee

[lestergibson]

Cheers all for the comments.

I found this:

http://www.homebuilt...dDewShield.html

which shows a simple dew shield for the Telrad. Just in case it helps anyone else.

Lee

I made that a few days ago using a flimsy cheapo mouse mat. Haven't been able to try it out yet though but if it doesn't work out I'm going try making a heater instead.

[ShellShock]

I've also made that Telrad dew shield, but have not tried it yet. You can get the materials from Hobbycraft shops in the UK, and online. Hobbycraft seems to have alot of branches. I had never been in before, and was surprised at the range of stock they have.

[Lee M]

I've also made that Telrad dew shield, but have not tried it yet. You can get the materials from Hobbycraft shops in the UK, and online. Hobbycraft seems to have alot of branches. I had never been in before, and was surprised at the range of stock they have.

Yes, we've had one open just up the road from us. I think I shall be calling in tomorrow.

I managed a quick 45 mins observing this evening. First time I got to use the Telrad properly. I think the finder scope will be coming off! Sooo much easier

[redneon]

I've been thinking about buying a Telrad but I have a hard enough time finding some things with the increased magnification from my stock SW finderscope. Surely, it'll be even harder with the Telrad as there's no magnification, is there?

[Planetesimal]

Yes, we've had one open just up the road from us. I think I shall be calling in tomorrow.

I managed a quick 45 mins observing this evening. First time I got to use the Telrad properly. I think the finder scope will be coming off! Sooo much easier

Why not use both together, or better still, upgrade to a right angled finder - it's easier on your back and the view through the finder is the right way up. I'm not sure a telrad would be enough on its own - you can get to a starting point but there are plenty of objects that are not next to visible stars, so you need to start in a known location with the help of the telrad, then move the finder to "star hop".

[Lee M]

I've been thinking about buying a Telrad but I have a hard enough time finding some things with the increased magnification from my stock SW finderscope. Surely, it'll be even harder with the Telrad as there's no magnification, is there?

I found it very easy and have found that you can use it both eyes open, kind of superimposing it on the unsighted eye. Or even viewing at an angle to see half a sight and sitting the target object on the centre of it. Sounds wrong but it was working perfectly for me last night.

Lee

[Lee M]

Why not use both together, or better still, upgrade to a right angled finder - it's easier on your back and the view through the finder is the right way up. I'm not sure a telrad would be enough on its own - you can get to a starting point but there are plenty of objects that are not next to visible stars, so you need to start in a known location with the help of the telrad, then move the finder to "star hop".

Yes, I'll hold off anything too dramatic until I've got a bit more experience. I like the idea of the right angle fionder and maybe a spacer for the Telrad to save me hugging the tube quite so tightly.

Lee