Here is what I did. I am writing this down so as to remind myself as well as share. If anyone has any suggestions to improve the flow, do let me know.
1. I modified my TC17EII by filing down the lug. Camera Hospital refused to do it for me saying "it is there for a reason". No choice, have to follow instructions online and DIY -
NatureScapes.Net • View topic - Nikon stack TC 1,7 + TC 1,4
2. After Step 1, the TC17EII will couple with the Sigma 150-500mm. But for the setup to work with V1+FT1, before coupling them, I used BlueTag to force the aperture of the Sigma 150-500mm to open up to max.
3. Zoom the Siggy to max. I then use maskiing tape to tape up the zoom ring area so that it won't slide back when the whole thing is point up at 70+ degrees.
4. Set the Siggy to OS "off", manual focus. And put the focus to infinity - this is very important. Else all you see will be darkness.
5. I then couple the Kenko 1.4x TC to the Nikon TC17EII. But before doing so, I must tape up the first two rightmost electrical contacts of the TC17EII so that the Siggy will work on the V1. Otherwise, the V1 will complain no proper lens attached.
6. DO NOT fix on the Kenko 2x TC yet - as with that amount of zoom it is VERY difficult to get the planet in the viewfinder.
7. Put on the V1 + FT1. I set the V1 to grid "off", manual focus, ISO 400, shutter speed 1/20sec, electronic shutter (zero vibration), and remote trigger (using my D7000 remote trigger).
8. Put the whole contraption on the gimbal. Turn on camera.
9. Now comes the hard part. I used SkyView to locate Saturn. Then very very patiently search the quadrant (absolutely pitch black) for the bright spot. The way I do it is to free the gimbal and rock the camera in the direction of the planet. Look for streaks of light on the LCD. Need luck!
10. Hopefully you got it in the center of the viewfinder. Lock the gimbal.
11. Slap on the Kenko 2x TC. Hopefully the planet should still be in the LCD. If not, DO NOT TOUCH the horizontal lock of the gimbal. Only loosen the vertical one and very slightly move your camera up.
12. The planet is constantly on the move. You have about 20-30sec before it goes out of view. Again, loosen only the vertical lock, and tweak the setup up. As the planet moves in an arc, you may be forced to loosen the hortizonal gimbal lock and look for it - good luck! I did that 3-4 times last night. On my last try, I lost it - could not get the planet back into my viewfinder. In the end, had to throw in the towel.
13. The second hard part - manually focus.
14. Fire away using the remote. While the going is good, fire as many shots as possible, possibly tweaking focus.
15. Suppose you got 5 good shots and want to stack them. Use Photoshop to crop the images. I find that using the fixed size selector of 300 pixels by 300 pixels and locating it so that the planet end up in roughly the same position works best for stacking. Also, using levels adjustment and bring the blacks in to about 80-100.
16. Then use Registax to stack the images.
RegiStax- Free image processing software
17. PP again using Photoshop to clean up.
Whew! I can't believe I did all that in the night after a full day's work