Celestron C14 visual issues

[bluesilver]

Hi,  I have just received a new C14 XLT,  so it is not the Edge version.

I am just curious to find out if i have a bad issue or just a very bad night for viewing.

I did a star collimation as i had the corrector plate out as i wanted to fix up some threaded holes for a top plate,  All good with the corrector plate, marked i to make sure it went back in the correct orientation / place.

I did clean the corrector plate as i did get a bit of dust, rubbish from the threaded holes first up.

 

But long story sort,  i thought i would try an get a look at the planets, Jupiter and Saturn,  it was nothing but a ball of mush no matter how i focused,  I was using a 20mm eye piece at the time.

So i though i would just check out the moon, nice and easy target,  still couldn't get a focus on that,  could make out the craters, but no a nice clear image through a 20mm  eyepiece.

 

Now i am not sure if the seeing conditions that night were completely rubbish,  i was a tad keen to get it out to try.

( I have a Skywatcher Esprit 150 of imaging and a 16" Dob for viewing,  so it is not the first scope i have ever had ).

Is this normal for the C14, or am i using too high a power eye piece?

The plan for this scope is imaging the planets when i get it sorted.

I am thinking of re moving the corrector plate again and re cleaning both sides + the secondary mirror,   But i am not really sure this is the issue as even dirty mirrors should give a decent image.

I am guessing it is seeing conditions on that night,  but hoping some C14 owners might be able advise if something is odd.

I have since now wrapped the entire scope in 10mm thermal insulation that they use on Automotive vehicles,  added a ZWO electric focuser and a dew heater for the corrector plate.

Any thoughts or ideas would be appreciated,

 

 

Edited September 24, 2022 by bluesilver

[CraigT82]

It won’t be dusty or dirty glass so don’t worry about cleaning them. Most likely poor seeing and thermals in the scope. Possible collimation too but you say it was ok?  Big cat like that needs good thermal management. 
Try a longer eyepiece, even a 20mm will give you 195x in a C14  which is probably too much for poor seeing.

[bluesilver]

Appreciate the advice.

Any recommendations for eye piece size for these C14 scopes?

Maybe look at say a 40mm that Celestron make?

I have never had much issues with the 16"Dob  but then again that is an open air design,  only occasionally get not so good views at the planets if seeing conditions are bad.

I have yet to try it out again with all the changes i have just made to it,  hoping these will limit tube currents and allow even cooling.

 

 

[dweller25]

It sounds like you have done all the right things.

A 14” SCT mirror is a large mass so reaching thermal equilibrium will take some time, I believe the wrapping will have significant effects 👍

[Elp]

Have you tried making and using a Duncan mask to check the collimation, very easy to use and can also be used to confirm best focus. 

Also dew on the corrector as you've now rectified makes a massive difference, you should be able to see the moon's surface quite easily with little trouble using a low power eyepiece but generally agree with the internal temp issue, you'll be able to see it if you defocus looking at bright stars and seeing any thermal wobbling in the donut stars.

Edited September 24, 2022 by Elp

[bluesilver]

Appreciate the replies and advise.

This is the first time i have ever head of a Duncan Mask,  it is now something that i am going to have to go and do a bit of a search and read up on,  sounds interesting.

Yes there was a bit of thermal wobbling when i was trying to do a star collimation,  so sounds like thermal activity was the cause for that nights viewing at least.

 

[Elp]

http://alpha-lyrae.co.uk/2013/12/31/schmitt-cassegrain-collimation-made-easy-using-a-duncan-mask/

To make it easier to make you don't necessarily need the thin section bits around the windows as the corrector plate ring will cover them.

Edited September 24, 2022 by Elp

[bluesilver]

Appreciated,  that made things a tad easier.

Will read up on that and get one made.

Greatly appreciated.

 

[Peter Drew]

If it's any consolation I have two 16" SCT's,  some nights they are fit for the bin, on others they can give awesome views.  Too early to panic, large SCT's take a while to tame.    🙂

[Paz]

Hopefully it is just temperature related as it's a difficult scope to cool. I have a 8" SCT and compared to a 14" reflector the SCT requires more thinking ahead to avoid tube currents. With the reflector I can turn on a fan to cool it faster and the fan will also break up the tube currents even when the mirror is still warm so the views are better than they otherwise would be right from the off.

[newbie alert]

A C14 will take more than a few hours to come to thermal equilibrium if you store it in the house..and warm thermals will cause the issues you describe...

[bluesilver]

Appreciate al the replies and advice.

It is sounding more and more like tube current due to the thermal differences as everyone has been pointing out which is greatly appreciated.

I have now got the entire scope covered in 10mm sound deading foam that they use in cars / vans including the rear and covered the rear vents also.

Theory is that will prevent any cool air entering the scope.

Also have a Celestron dew heater on the corrector plate to keep that from cooling and dewing up also.

I am keen to see what happens next time i get a cloud free night.