I use the ST-9E without the 1.25" nose assembly shown in the photo at right. In fact, I use the ST-9 without a nose at all. The camera T ring adaptor screws directly into my filter unit. That unit is supplied by Al Shugart as are the BVR and clear filters I use for photometery. The Shugart filter holder has a 2" adaptor that slips into the 2" focuser on the NGT-18.
The FIlter holder is a manual affair in which a filter slide slips out of the filter holder. The filter can then be manually slipped into the holder and replaced in the unit with minimal disturbance to the mount. The filter slide is held into the holder with detents just as the filter is held in the slide. all in all a reasonable worrkable arrangement.
Ongoing calibration:
It seems that each new piece of equipment added to the system automatically adds another layer that requires calibration. I am learning tons. The main thing I am learning is to stop adding things to the system.
I have been getting a bit of light leakage and didn't know where it was comming from. Finally, I took the scope out into daylingt and looked into the focus tube. Wht I saw amazed me. The source of my light leakage.
The JMI focuser is not painted flat black, but rather is painted a matt which reflects light. When I looked into the focuser, I saw a bright ring of light reflected by the focuser. I then took the camera off of the filter unit and stuck it inside the focuser tubed got my second suprise. The inside of the 2" adaptor ring for the filter holder was painted matt as well and reflected a good deal of light which made it not only to my7 eye, but would make it any eye at that position whether the eye be home grown, or ordered from SBIG.
I then did the daring thing. I got two Klenex's and sprayed one with flat black Rustoleum. I then wiped the inside of both the focuser and the filter holder with the painted Kleenex. I repeated this wiping about 5 times letting the previous application dry before the next was applied. What I wound up with was a very flat black non-reflecting surface.
5/3/01
Last eveninng, I completed the installation of my polar aligned pier. It's a simple affar consisting of a flat, relatively unused segment of my driveway. In this area, I have placed six 18"x18"x1.5" concrete patio blocks in a 3x2 pattern, with the 3 brick axis on a north/south line. The broad side of the platform points east/west. On top of the patio blocks, I arranged three standard bricks, one for each leg of the NGT-18 azamuth adjustment platform.
I roughly polar aligned the telescope by scooting the metal legs of the azamuth platform across the top of the standard bricks until I was more or less polar aligned.
I then fitted three metal squares each having a 1/2 inch hole atop the standard brick, and positioned the metal such that the half inch bolt supporting the azamuth adjustment platform went right through the hole for each of the theree legs.
I did a final polar alignment using the fine azamuth controls.
Then on a leg by leg basis, I raised the azamuth platform bolt, removed the brick and the metal piece, epoxied the standard brick to the patio brick, then epoxied the metal piece to the standard brick, and re-alligned the azamuth platform bolt and screwed it down firmly to hold the brick and the metal piece in place.
Forty minutes later, I performed the same operation on the second standard brick footing.
Forty minutes later, I epoxied only the metal piece to the standard brick. Securing the stndard brick to the patio brick is not necessary because having two bolts aligned guarantees the alignment of the third.
Lastly, I took an image of a piece of sky. The atmosphere was murky, but not overcast. The visual magnitude may have been as high as 2.0. Some interesting images can be taken in skies like these. Click here to see.
