Meade SCT Mount Focal Reducers

I was somewhat perplexed with the placement and actual focal reduction of the Meade f6.3 and the f3.3 focal reducers that I decided upon testing them with my equipment.  I had previously tested the 1.25" nose piece mounted Atik and Mogg focal reducers using M-103 so I decided to follow the same format of testing and use M-103 as my target again.  The equipment used for this test:

  Meade LX-200GPS/SMT 10" f10 Telescope on a Mitty Evolution Wedge
  Meade DSI Color CCD Imager
  Meade f6.3 Focal Reducer
  Meade f3.3 Focal Reducer

F3.3 Light Train
The basic light train for the f3.3 focal reducer consisted of the SCT with a Peterson Eyeopener II which is followed by the micro-focuser.  A Televue 2" nosepiece was screwed onto the front of the focal reducer which was then inserted into the rear of the micro focuser.  On the rear of the focal reducer either a T-Adapter or 1.25" barrel with thumbscrew was used.  A Televue T-Adapter was used as it is a one piece assembly instead of the Meade supplied T-Adapter which is two pieces.  Most of the testing was performed using the T-Adapter which was then screwed onto the DSI without it's 1.25" nosepiece.  Extension tubes of 15, 30 and 50 mm were inserted between the T-Adapter and the DSI in various combination to vary the actual focal reduction.  The following represent the various f3.3 light train combinations:

  SCT | Eyopener II | micro-focuser | 1.25" Adapter | DSI with nosepiece

  SCT | Eyopener II | micro-focuser | FR | T-Adapter 1.25" barrel | DSI with nosepiece

  SCT | Eyopener II | micro-focuser | FR | T-Adapter | DSI

  SCT | Eyopener II | micro-focuser | FR | T-Adapter | Extensions | DSI

The extension tubes could be connected in seven different combinations yielding extensions of 15mm, 30mm, 45mm, 50mm, 65mm, 80mm and 95mm.  Focus was unattainable when using combinations that were greater than 50mm.

F6.3 Light Train
The light train for the f6.3 focal reducer consisted of the SCT with the f6.3 focal reducer screwed onto the rear of the SCT which was followed by the micro-focuser.  A  Televue T-Adapter was  then screwed onto the DSI without it's 1.25" nosepiece.  The following represent the f6.3 light trains used:

  SCT | micro-focuser | T-Adapter | DSI 

  SCT | f6.3 focal reducer | micro-focuser | T- Adapter | DSI 

TESTING
The night of the test was July 20th 2005, the 36th anniversary of Neil's first step.  The Clearsky Clock indicated both poor seeing and poor visibility.  The moon was bright and hazy over the Southern horizon.

Nine images were acquired using the Meade Autostar Suite.  Each image consisted of at least twenty stacked images with a minimum quality setting of 50% with an exposure of 0.5 seconds.  All other settings were nominal, auto color - no dark subtracted - auto contrast.  The images were converted to FITS images and then analyzed using the AIP4WIN software to measure the pixel distance between two stars within the cluster.  Two sets of measurements were done using two pairs of stars as depicted in the following image of M-103.

The following tables & images summarizes the actual focal reduction data.

f3.3 FOCAL REDUCER DATA

f6.3 FOCAL REDUCER DATA

The following are the images used to derive the f3.3 f/r data.  

The following are the images used to derive the f6.3 f/r data.  

CONCLUSIONS
Apparently, the advertised f3.3 and f6.3 are unattainable with my LX200GPS telescope.  This is most likely due to the variable nature of the Meade LX-200GPS telescope's focus mechanism.  Using the supplied spacers with the f3.3 focal reducer you can come close.  Using the 15mm spacer you can come close to f6 and if using both the 15mm and the 30mm spacers you will come close to f3.  

The f6.3 focal reducer when installed as Meade recommends was not close at all.  It calculated out to just under f5.

The f6.3 requires that I remove the Peterson Eyeopener II each time I use it.  When the f6.3 is installed along with either of my 2" diagonals, the diagonals only clear the base of the fork casting if I run the micro-focuser all the way in to its mechanical stops.  I can't get to Polaris for the iterative alignment dance any other way.

Since I use the focal reducers for imaging only, I have found it more versatile and convenient to use the f3.3 focal reducer and various combinations of the spacers.  I fear my f6.3 will gather some dust.  

C.A. Jagow