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I have had a few FSQs. Venerable FSQ106N and the FSQ106EDX111.
The latest version of the FSQ106ED replaces the captains wheel part which was usually simply locked down and never used (to rotate the focuser for framing) or rarely used with a solid cast piece to prevent flexure.
FSQ106N has a rock solid focuser with a knob on top for locking down focus. I never saw tilt or flex on that with Apogee U16M. Not sure if I had the Proline then, I don't think so.
FSQ106ED has better colour correction. I have read numerous posts on the Tak uncensored forum from people complaining of flex in their FSQ106ED. Then again the 106N gives some nice colours and you are fond of blue aren't you!
One simply fix was to tighten the focuser adjusters under the focus mechanism. It put pressure on a Teflon block. I think later models changed that to some other system like a metal block or perhaps it was the Teflon that got added.
Anyway. I used exactly what you are saying, a Robofocus, MMOAG and Proline 16803 but I had CFW 4/5 (still have it) which is significantly lighter and smaller and less prone to flex. The CFW 5/7 as you know is large and heavily leveraged off its connections and I think is a force that could cause flexure. I have managed to minimise or eradicate (?? mostly) flex from it with my CDK17 and RHA. But I did seem to get more flex/tilt once I started using it. Mind you I like the 2 bolts that bolt the Proline to the CFW 5/7.
In the future though, if I do get another CFW it would be the centreline as the 5/7 is taking things a bit to the extreme.
My FSQ106ED had no flex and I got round stars to the corners every time.
The Robofocus worked well and you need to get the Tak FSQ bracket and bush that connects the Robofocus motor to the main focuser spindle (not the micro focuser spindle).
FSQs are very temp sensitive so a good addition would be the Lacerta/focuslock setup by Optec (its cheap) that enables continuous autofocus. That would be invaluable on the FSQ as every 1C change requires a refocus (probably true of most scopes but very noticeable on the FSQ).
As far as FSQ106N versus FSQ106ED111 or IV goes. The main differences are the colour correction is better on the FSQ106ED and there is no vignetting on the FSQ106ED. The 106N in my opinion gave richer colours due to its 2 x fluorite elements but it also was a bit soft in the blue channel and also gave weird dark bars in bright stars along the edges of the image. Have a look at some of Rob Gendlers FSQ106N images and you'll see the effect.
106ED internal tube black paint gives a green cast. I found this out because when the FSQ106ED first came out I could always tell an FSQ106ED image as the colour looked a bit mustardy and sterile. I mentioned this to one guy who then tested his FSQ106ED and found it was indeed slightly green biased. He traced it back to the internal paint (I thought it was the new mustard coloured coatings as the FSQ106N had a lovely grass green coating).
Anyway I replaced my FSQ106ED111 with a TEC110 fluorite F5.6. Immediately I noticed the TEC got better and richer colour but it was a bit of a struggle with the focuser as it was not designed for the heavy Proline. I got it to work but it wasn't ideal. I really should've removed the focuser altogether and installed a solid tube adapter and used a FLI PDF focuser.
Anyway I am saying that about the TEC so you get the colour aspect of the 106ED. Its not quite spot on and it would be one aspect I would be checking out about the FSQ130 if they have remedied that.
The focuser lock on the FSQ106ED is a waste, locking focus actually shifts focus. The 106N had a very good one. But you won't use that with a Robofocus anyway. I had a standard Robofocus and it worked fine. Although if you went past focus it wasn't a matter of going back in the same amount you went past it. So there was some backlash but same with the FLI Atlas.
FSQ106EDX1V would be my choice but 106N is probably cheaper but not by as much as you would think. On Astromart they seem to go for about US$3000 whereas a new FSQ106ED is now around US$5K I think.
A classic scope and a great combo.
The FSQ130 has still yet to arrive in anyone's hands that I have seen so to this date remains vapourware but I still think its about to arrive. They must want to make sure its perfect and they must've had some issues with it.
If I did get another scope in the future that would be one I would be interested in but at US$12500 its an exotic instrument and the 5 inch focuser would have very expensive adapters! I am also not sure how much better it would be over the 106ED as it only has a slightly longer focal length. The new AP130 with its Ubeaut widefield corrector would possibly be similar for much less and perhaps less temperamental.
Greg.
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