Cooling my C11 SCT

[A.S.I.G.N_Baz]

Well, I raided the tip for some computer fans and coolers....I have been a busy boy tonight.

I was a bit nervous about pulling the scope to bits to do this, but it is well and truly out of warranty now and I am fairly confident I know what I am doing....

I will be writing a FULL tutorial and have LOTS of photos, so stay tuned folks!

Baz.

http://i26.tinypic.com/21do95d.jpg

[Radar]

Wow! Looks awesome mate. That's gonna make a huge difference. Would love to see a comparison photo sometime.

Ray

[Tenacious Del]

i know this sounds like a silly question, but does cooling a telescope down make that much difference?

[A.S.I.G.N_Baz]

No Del, no difference whatsoever, I just thought it would be fun to destroy a 9K telescope.:lmao:

Seriously though mate, I can only go by what is recommended by other astrophotographers. Their photographs through actively cooled telescopes speak for themselves.:eartoear:

[timthelder]

Hi Baz, I do have one querry about this project. It has to do with the cooling down of the internal optical tube down past the dew point...

I suppose I could inquire to some who have already done the modification, but isn't cooling the inside of the tube going to cause the corrector plate to fog up? I can see it not being a problem in the winter, or cooler months, but in the summer when the outside ambient is 80F and the inside of the tube is 40F, looks like this might cause a teensy problem.

Just curious if anyone else who has done this modification has mentioned this...

I am going on the same principle of what happens when using a peltier on an imaging sensor. Without it being in a sealed humidity free chamber, it fogs up at and below the dew point.

[A.S.I.G.N_Baz]

Wow! Looks awesome mate. That's gonna make a huge difference. Would love to see a comparison photo sometime.

Ray


Thanks Ray,

The project is coming along beautifully mate. As I am a "can do", and "have a go", and "you never know until you try" kind of a guy, I am sure this will be an interesting, informative and positive outcome that will enhance the quality of my astrophotos, if only even slightly. The aim here is to share this experiment and it's results with others who may wish to explore outside their square a bit.

I learned something in the Army a long time ago. It was called, "What if?....So what?"

Every time someone came up with a plan, a person would say, "What if?", to which you would reply, "So what?" and give your counter. This was a healthy way of working out what to do in the face of adversity. A very handy tool when undertaking something with some risk involved for a possible gain or improvement.

I am very grateful to Paul Haese of Southern Celestial Pole for the inspiration to attempt this. He and his friend Anthony Welsey pioneered this Mod and allowed folks like me to humbly follow in their lead. I can only hope to pass the baton to the next bloke as they did for me.

Baz.

[A.S.I.G.N_Baz]

Hi Baz, I do have one querry about this project.
I suppose I could inquire to some who have already done the modification, but isn't cooling the inside of the tube going to cause the corrector plate to fog up?

Just curious if anyone else who has done this modification has mentioned this...

Hi Tim, I can see where you are going with this. I honestly don't know how it is going to react mate. I guess I will cross that bridge when I come to it. A couple of things come to mind straight away...dew heater (possible solution).....the fact that my scope is housed in a large dome may not be a cause for concern with the humidity inside being different to what is outside (sheltered as a pose to exposed).

Time will tell mate. I will let you know in any case.

Baz.

[Rumples Riot]

Short answer to these questions is this.

This system works so well that my images this year are testimony to how this works. A C14 would not cool down over night much less with several hours of cooling. Quite simply it works.

So, no dewing up at all ever seen, the scope is essentially a sealed unit. In summer this is more effective than during winter. Never any dewing on the mirror or inside of the scope as a result of the modification. I have done all the testing and as the designer of this system for an SCT I can state this categorically.

Ray, the difference is stupendous. I hope in years to come that all SCT's will be fitted with this out of the factory. SCT's have terrible problems cooling. This system allows for better viewing and imaging results both early in the evening and having the ability to control the core heat release during the night.


One thing that I have not stated in my Tutorial and I found this out later. The bottom seal between the scope and mirror back needs to be sealed to prevent dew running down the outside of the scope into the inside of the scope. If you do this, you will never have a problem.

Please follow the link for my Tut.
http://southcelestialpole.org.au/howto/coolingC14.php

Also see my site for my images.

http://paulhaese.net/

[Radar]

Interesting, I might look into doing something like this with my 8 inch.

Ray

[CanisMajorTom]

very cool, (pun intended) :wink:

[A.S.I.G.N_Baz]

Success!!!

I changed the wiring today and did a 10 minute bench test. NO HOT WIRES!!!. Fans are running well and the aluminium mirror back got nice and cold. The heat sinks were just warm, showing that the peltiers were working well. I used 25 amp wire from power supply to the scope and from the inside of the plugs to the junction of all the other wires.

Thanks to all for your tidbits of advice and experience. I learned heaps! Paul and Anthony, you blokes are legends! What a great idea!

Tomorrow I will flock the tube and put it all back together for a full test. I will post the results as soon as it's done.

Baz.

[A.S.I.G.N_Baz]

It's all done! For the test, I started with a room temperature of 10.5 degrees, whils the inside of the scope was 12.6 degrees. From the flick of the switch it took 35 minutes to bring the mirror down to 10.5 degrees.

I am happy now, except that now I have it all working, its new moon and overcast....

Typical..

Ah well, time for lots of other improvements around the observatory. My chair needs recovering.....

Baz.

[timthelder]

Looks like an excellent, 'job well done', Baz...Be sure to keep us posted on your review of this modification.