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Old 29-06-2020, 10:05 PM
Tasaurora (Si)
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Variations in temp - collimation

Iím a newbie to this site and the astronomy world in general and I have spent wayyy too much time reading posts - one thing, if I may offer the community in regards to responses (especially in the beginner section ) - could ppl please be aware that as beginners, we do not know, what we donít know. So the acronyms and the 3 letter references within some replies no doubt make perfect sense to long termers - But I often find myself sidetracked looking up reference after reference, and then - well going off to watch a funny dog video :-)

Iím guilty of the exact same thing in my other, established hobbies - and someone bought it to my attention re the same I ssues it can cause - and I for one, want more ppl involved in the hobbies I choose.

To my query if I may - my scope lives inside where itís 21-22 degrees C for most of the night. When I take it outside itís often 1-2 degrees. This causes not only condensation to build quickly - but I can hear the scope creaking and ďcrackingĒ as it cools down. Is this a problem? Can it cause collimation issues? How do ppl deal with condensation in the field ?

I got to use my 10Ē dobson for the 1st time the other night and kids went mad for Saturn - but it was a little blurry regardless of eye pieces I trialled.
I also made a bad error, getting the kids to look early in the night - looking through a lot of atmosphere To the east rAther that waiting until closer to vertical - silly, but time was a problem.

Iíve looked at collimation links on here and am about to buy a Cheshire and laser - is collimation something one should check every night - after travel - intermittently? Again - I donít know what I donít know - so perhaps I need collimation now after interstate transport...how far out is too far out ?

One other Question - Iíve not yet set up skyscan because I cannot get a perfectly level site and donít want to put feet into the grass / dirt - as this might introduce backlash as the ground is very soft - I imagine this is critical? So build a board or sheeting is a decent idea?

Thanks in advance for all assistance- so, so much info on here. Gave me absolute chills seeing Saturn come into focus - I was like one of the kids myself
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Old 30-06-2020, 12:18 PM
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Tulloch (Andrew)
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Hi there, before using your scope you should leave it outside for a few hours to reach ambient temperature (this will stop air currents inside the OTA and so the images will be more stable). I also use a BBQ cover over my scope so that condensation doesn't form on the scope while it's cooling.

To deal with fogging/condensation I use a portable fan heater and blow warm air over the corrector plate (on my SCT). After a couple of minutes to cool down again, it should be fine for the next 15 minutes or so.

In a few months the planets will be viewable at a more reasonable time of the night

Andrew
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Old 30-06-2020, 12:55 PM
Startrek (Martin)
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I have a Skywatcher 12Ē Goto dob and use Kendrick dew heaters under the secondary mirror , around the finder scope and sometimes on eye pieces ( depending on the severity of dew ) to combat the onset of dew which can ruin your night.The primary mirror is rarely affected by dew
Iím assuming your 10Ē is a Goto Scope not a manual push , pull , nudge ?

If your going to use it continually in the backyard and not elsewhere, Iíd recommend to buy a precast concrete pad /s and set them level under a bed of gravel so you have a permanent reliable observing platform for your scope to sit on each time you use it ( or alternatively on a driveway or paved entertainment area or the like ) I think a 10Ē base is only around 500mm in diameter and I know you can buy precast 600mm x 60mm thick concrete pads from Bunnings

Many factors can contribute to poor observing especially planets -
Dew
Humidity
Collimation
Mould, salt , oils etc on mirrors
Pinched primary mirror
Jetstream and atmospheric turbulence
Light pollution
Moon glare
Smoke
Bad Focus
Over magnification
Poor quality eye pieces
Low observing altitudes
Etc .......

PS: I know you hate acronyms but get use to it , the hobby is full of them especially Astrophotography !!!!

Welcome , good luck and enjoy your new journey throughout the universe

Clear skies !
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Old 01-07-2020, 12:52 PM
Tasaurora (Si)
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Thanks for replies -have given me even more to think about lol.

I donít mind acronyms when I know or understand - like anyone I guess - itís just when starting out it can be like learning a new language...

My sky watcher dob (see, itís creeping in for me now lol) is a GOTO - but at present, Iíve just been using the hand held device to move the scope and the finder scope.

Might look at setting up a dedicated area and even pour a small slab.

Thanks again.
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