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ASTRO: CPT18 frame received



 
 
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  #1  
Old February 21st 04, 01:29 PM
Richard Crisp
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Default ASTRO: CPT18 frame received


Some folks here were interested in the 18" scope I mentioned I was building.
This is based on the CPT18 from Resource International. I am making
modifications to permit it
to be used as a Classical Cassegrain or as a Newtonian, as it was originally
designed.

In Cass mode, it will be f/12.6 using a 3x multiplier for the
secondary. The illuminated field is 49mm, designed to support either
a 35mm negative or one of the new STL11000 cameras from SBIG.

In Newt mode, it will have a focal ratio of f/4.2.

Here are some pix of the frame in the back seat of my wife's car.

http://www.rdcrisp.darkhorizons.org/...8_bmw540_1.jpg

http://www.rdcrisp.darkhorizons.org/...8_bmw540_2.jpg

The optics are the pacing item, with expected delivery in the
May/June timeframe. I hope to have first light about a week or two
after receiving the optics if all goes well.

It is an aggressive project for sure, but I am optimistic that the
results will match expectations.

if interested in the CPT scopes you can see them at the Resource
International website.

http://astronomy-mall.com/regular/products/cpt/


  #2  
Old February 25th 04, 05:49 AM
David Whysong
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Default ASTRO: CPT18 frame received

In sci.astro.ccd-imaging, Richard Crisp wrote:

In Cass mode, it will be f/12.6 using a 3x multiplier for the
secondary. The illuminated field is 49mm, designed to support either
a 35mm negative or one of the new STL11000 cameras from SBIG.


That's a great idea, but an 18" 'scope with that focal ratio means the
STL11000 pixels subtend only 0.32 arcseconds.

In Newt mode, it will have a focal ratio of f/4.2.


....which is much more reasonable for 9 micron pixels. Why not use
it for imaging in this configuration with a large coma corrector?
Would that work?

Dave

David Whysong
DWhysong (at) physics (dot) ucsb (dot) edu
  #3  
Old February 25th 04, 04:30 PM
Richard Crisp
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Default ASTRO: CPT18 frame received


"David Whysong" wrote in message
news:yHW_b.11655$aZ3.7402@fed1read04...
In sci.astro.ccd-imaging, Richard Crisp wrote:

In Cass mode, it will be f/12.6 using a 3x multiplier for the
secondary. The illuminated field is 49mm, designed to support either
a 35mm negative or one of the new STL11000 cameras from SBIG.


That's a great idea, but an 18" 'scope with that focal ratio means the
STL11000 pixels subtend only 0.32 arcseconds.



You can also bin 2x2 which offers a lot of advantages including image
processing time.



In Newt mode, it will have a focal ratio of f/4.2.


...which is much more reasonable for 9 micron pixels. Why not use
it for imaging in this configuration with a large coma corrector?
Would that work?


just might, Dave.

I have lots of options as to how I instrument it.




 




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