Dew on objective lens or corrector.

[Grump Martian]

In the past I have always used a dew shield to overcome the problem of dew build up on Maksutov or SCT telescopes.

So out observing on the first clear night for ages. I used my 102 mm Starfield refractor. Nice long dew shield. But the objective lens was sopping wet with dew. I've never experiences dew on a refractor and eyepiece before. Has anyone else suffered this on a refractoe before? Is there a dewstrip available for refractors and eyepieces?

[DirkSteele]

A couple of times but in really bad conditions. The air was dense with moisture and it was visible in a torch light. Eyepieces are more vulnerable and have lost many to dew over the years.

 

heated strips are available for both.

[ONIKKINEN]

You can put the dewed up eyepiece in your pocket to warm up for a few minutes and use another eyepiece in the meanwhile, shouldn't take too long if you do the swap as soon as dew starts to form. For the scope lens you will need a long dew shield or a heating strip around the lens cell, or both if its really humid.

[GordonD]

Yes my objective dews up quite often even with a reasonably long dew shield. So I got a dew strip that certainly helps although it is another thing to have to set up and yet more cabling. I do get condensation on the eyepiece but only when I get too close for extended periods and that evaporates reasonably well with a bit of fanning. (must get a little blower at some stage).

[mikeDnight]

My first FS128 dewed over regularly, so I simply brought it back into the house and allowed it to thaw naturally. I've also used strap on dewshields such as AstroZap and they work well. Another thing I've done with my 100mm refractors is cut the toe out of a woollen sock and pull it over the Dew shield and lens cell. The latter is very effective though amusing to onlookers.

Edited August 20, 2023 by mikeDnight

[JeremyS]

1 hour ago, mikeDnight said:

 Another thing I've done with my 100mm refractors is cut the toe out of a woollen sock and pull it over the Dew shield and lens cell. The latter is very effective though amusing to onlookers.

Isn’t that what your 80’s leg warmers are for Mike? 😊

I have used such on my FS 102, with hand warmer packs, but don’t tell anyone 🤫

Edited August 20, 2023 by JeremyS

[JeremyS]

56 minutes ago, mikeDnight said:

My first FS128 

Now there speaks a true Tak man 👍🏻

[Clarkey]

Surely for a Tak, it's a hot water bottle and a blanky 🤣🤣

[dweller25]

I put an astrozap dewshield on the end of my refractor dewshield - seems to work.

But a dewshield made out of a black camping mat would be just as good and cheaper.

[Grump Martian]

2 hours ago, dweller25 said:

I put an astrozap dewshield on the end of my refractor dewshield - seems to work.

But a dewshield made out of a black camping mat would be just as good and cheaper.

Hi Dweller. So you're not using a heater strip,just an extended dew shield?

[dweller25]

Correct

[bosun21]

My Starfield 102 dews up quite often and can freeze over in the winter. Easily remedied by a dew heater strap wrapped around the tube where the objective is. I also use one on my eyepieces and finder on nights of heavy dew. I always switch them on before any dew forms. As the saying goes “prevention is better than the cure “.