sw 200p

[Gazer914]

just wanted to ask what the recomeded cool down period for a explorer 200p is before viewing? and for this size scope would it be recomended to get a dew sheild?

[Skybrowser]

Trial and error really. I'm not sure how you actually know when it's sufficiently cooled down. I give mine 30-45 mins before I start observing. I've got a dew shield and it works really well (only had my 200P for a couple of weeks and not had any probs yet). After the cool down period I get my eyes really well dark adapted and then hit the eyepiece.

[Gazer914]

i just got mine today the only thing i dont like is where the flexi grips have been replaced with just knobs for the r/a and dec adjusters but think i should be able to buy these for it shouldnt i?

on the bonus side when i ordered it from RVO in the add its said it had a polar scope holder but not the polar scope guess what its come with hehe BONUS....

[jimmyjamjoejoe]

It varies night to night, depending on the temperature difference of course. Most nights i found about 40minutes to be properly cooled. I have had nights where even after well over an hour, it still wasn't cooled. I just keep it in the car now, it's always ready to go.

Star testing will tell you when it's ready.

[Gazer914]

does the size of the scope affect the cool down? would have thought it would because of the size of the mirror.

[jimmyjamjoejoe]

Yep, size and type make a huge difference. Some larger mirrors never reach equilibrium without active cooling. Cassegrains take ages to cool down too.

[Catweazel]

I leave mine for about 45 mins to an hour

[Gazer914]

ah right wasnt sure with the big scopes, another question i have and dont know if this is a prob or not, the eq5 that came with the scope i have balanced but when decreasing the alt with the T bolt the front of the scope kinda bounces, like i said not used to setting up such a big scope, would it be worth greasing the T bolt? have included a pic to show where i mean.

[Moonshane]

as a general rule I'd suggest 5-10 minutes per inch of aperture for all scopes - refractors also need to be cooled to give best performance.

that said, as others have commented, I can start observing with my 16" dob almost immediately at low powers especially when the fan is on.

it's relatively rare for optics on a newtonian to dew up - possibly with the exception of truss based systems. all newtonians will benefit from a light shield rather than a dew shield especially if you have a solid tube design or observe from urban locations. stray light from kitchen windows etc creates a reduction in contrast if it enters the light cone. see this link http://www.urania.be/forum/download.php?f=1&file=baffling.pdf

for ways to prevent this.

[Gazer914]

lighting isnt too bad even though i live in town, they tend to turn some of the lights off after a certain time so have had some good veiwing, saying that because dont live that far from the coast tend to get alot of damp nights so condensation is a prob at times (sea mist) am hoping for a clear night tonight so will see how things go