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I have used both the FSQ106N and the FSQ106EDX.
Firstly the current version of the FSQ is the FSQ106EDX111.
It has replaced the unpopular captains wheel with a molded solid connection between the OTA and the focuser. It has a camera angle rotator.
I have said that before that the 106N series with the fluorite seemed to produce more colour saturation and colourful images than the 106ED.
I have had some say it is all the processor of the image and not the scope.
I disagree. I imaged extensively with both and processed the images the same way. The difference was the scope. Now why is another matter. I do not see ED lensed scopes in general doing worse than fluorite Tak doublets in the colour department. Usually quite the contrary as fluorite triplets are rare and Tak mainly made fluorite doublets which unfortunately were really high end semiAPO's.
Fluorite does have very little light scatter. It therefore has slightly better throughput. It may be very marginal though. Perhaps it is more likely something to do with the lens coatings which are clearly different.
The 106ED is probably sharper (the 106N is very sharp though).
The 106N had a slight problem with vignetting where bright stars along the edges of the image only, had a dark tunnel through them. I am told that was vignetting.
106N has a better focuser (stronger), better focuser lock (the 106ED causes focus shift when you fully lock it a real flub by Tak whose reputation for focusers is really great).
The 85ED has returned to a focuser setup that looks like the 106N so the Tak engineers probably know of this weakness.
The 106ED though has better backfocus (which means you can use your normal diagonal and could use binoviewers which you can't with the 106N).
Really the major feature for me is the 106ED reducer. It is a work of optical art and transforms the scope to even widerfield and F3.65 and superwidefield. The reducer as mentioned does not work on the 106N.
That question was often asked on the Tak uncensored site.
Yes Jase is right, F5 is plenty fast and wide enough. But the reducer opens up a whole new world and yes the critical focus zone becomes even narrower.
I would suggest a Robofocuser for either model. I just got a Robofocus with the special FSQ mounting plate plus I got the shaft connector specific to the FSQ106 otherwise Robofocus tends to wobble as the shaft connectors have too big an opening and cause a wobble of the motor.
As to the colour saturation issue I would also point out that Rob Gendler exclusively used the 106N and his widefield mosaics are to this day in my opinion unsurpassed for beauty and colour saturation. Just stunning.
Having said that the 106ED is a highend scope. FSQs rule the world of small wide field imaging and have been the best available scope for some time. I am told the Pentax 125 is like a 125mm FSQ (its also a Petsval).
An FSQ125ED would be an awesome future Tak product. Imagine a Tak FSQ150ED - oh my!
So either scope is a real gem and pretty much the best you can get for its aperture. The TMB105/6.2 was a competitor for a while. There is an AP scope that is about 106mm as well.
A 2nd hand 106N is quite a bit less than a new 106ED. Also keep in mind when you buy a Tak scope the first thing you realise is there is an extra $800+ needed to be spent on rings, finder scope, case etc. A 2nd hand one often has these expensive items included.
There may be a serious competitor with the just released TEC110mm eclipse fluorite triplet. It is US$4,500 which is pretty good as it comes with rings and a case I think. Yuri makes a field flattener for it and it is F5.6.I think that makes it about the same or close in price as a FSQ106EDX111 with rings and a case.
So you can have your fluorite and eat it too hehehe. No images from one yet so it is more of an expectation. I am expecting one in the coming few months and I can let you know what I think of it. TEC though make superlative scopes so I am expecting a lot from it. The main reason Yuri used fluorite is it enables him to get faster F ratios with the same colour correction. Colour correction is "easier" to achieve with higher F ratio scopes than fast F ratio scopes.
Greg.
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