Quote:
Originally Posted by strongmanmike
Thanks Greg, I have decided I need a 17" CDK  
Mike |
Hi Mike,
A 17" CDK - that's a lot of money.
You could start a whole new thread on that?
Some quick calculations not taking into account secondary obstruction sizes - which I suppose you have already done?
The 17" at f6.8 will be 38% slower than your 12" f3.8 Newt.
Focal length = 2936mm.
With the
CDK Focal reducer = 0.66.
Focal length = 1813 mm -
speed 43% faster than your Newt.
Using your camera at 4.54 micron pixel size - the ratios are:
With Newt FL = 1158 mm = 0.81 arcsec/pix.
With CDK at FL = 2936 mm = 0.32 arcsec/pixel.
With CDK reducer FL = 1813 mm = 0.52 arcsec/pixel.
Conclusions.
using the principles of the Nyquist sampling Theorem.
The full focal length of 2936 mm would confirm once and for all
if you are getting less than 1 arc second seeing.
The 0.66 reducer would allow you to take images faster than your Newt now.
You could run a much larger camera sensor without vignetting.
The 10" back focus of the CDK would allow you to install adaptive optics
which would take full advantage of the seeing.
Would you break the 1 arc second barrier?
Would you get some pictures as good as CHART32 on some nights?
cheers
Allan