Cooling down my 12"

[Tony.S]

I've just realised how important it is to let my 12" dob cool down before I use it.

The last 3 or 4 times I took it out I used it straight away & was not happy with the scope,to the point of thinking there was something wrong with it.

Tonight I done the same but after 20 mins saturn was still not sharp.A bit fed up I got my Nexstar 5SE out & straight away I had lovely sharp images on it & just ignored the dob.

After about an hours viewing the Nexstar was "dewing up" (I also found out the a dew shield is needed for the Nexstar)

Before I gave up for the night,I had another look though the 12" & wow...a superb sharp image,I threw my most powerfull (only 8mm EP) on it & 2 x barlowed it & still sharp images..I only have cheap EP's but these big dobs must be really excellent with top-end EP's.

I am now back in love with my 12"

[John]

I used to find my 12" Meade Lightbridge needed a good hour to get to something close to ambient temperature and then improved a bit more beyond that. Of course it takes longer in winter as the temperature difference is that much more.

I've owned 2 C5's and a C8 and found they took longer to fully cool than newtonians. Dew shields are pretty much mandatory with SCT's really.

[Doc]

At least 90 mins in my 16" Lightbridge maybe even two hours to really be cooled down.