fsq 106..to reduce or not to reduce!

[libraryman]

Has anyone found that using the Tak reducer on an fsq has downsides?

I want to open up more imaging options to my qsi583, the fsq106 and the 583 sensor are well matched but I want to increase my field of veiw.

The reducer is at 1st glance the most attractive option, however focusing and adapter costs make me wonder if its a wise move!

I don't see many on the used market, is that because they are so good or is it that they have a downside?

Ray

[ollypenrice]

They're very good, especially with your chip, and do just what you want them to do. However, faster is always trickier and the downsides are;

- Tilt must be eliminated. The Tak reducer has three silly little allen keys intended, we all suppose, to tune out tilt. Most people find they introduce it, so if you have a problem loosen them, put the reducer bottom on a table and push the top down while retightening them. This has worked for me and for others.

- Focus. The later ED 106 like yours is particularly fussy on focus during cooldown. Our older Fluorites are not so bad. The problem seems varied and probably depends on environment, so here 106ED owners do see rapid focus drift whereas Velvet in Derbyshire doesn't. If you see it unreduced it will be worse reduced, that's the key point. Automated refocus between subs would be ideal but if yours is stable at the moment you should be OK. If you autofucus already then fine.

- You do need to get the chip distance right. It is best to call in the help of Tak experts like Texas Nautical Repair, Optcorps or Ian King to get a precise spec for your camera and filters. You'll probably need to get something made but if your QSI has the built in autoguider you might get away with some proprietory screw-together extenders because of your long internal chip distance.

I used the reducer regularly on my Baby Q but it cannot be used on the old fluorites, nor is it entirely happy covering the 37mm side of the big Kodak chip anyway.

Olly

[libraryman]

Cheers Olly, i do already have some variable tilt, i guess basically because i use my own extenders..i intend to machine a new one with closer tolerances in the new year.

that said, it is only about 0.1" to 0.4" arc sec on each axis.....this is how CCD inspector reports it...i think its arc sec's.

It doesn't sound a lot so i hope it isn't...truth is i don't really know....id prefer a big fat zero then I'd know for sure

Funnily enough, it does vary with focus but never higher than 0.5"

focus does seem reasonably stable, i don't live far from Derbyshire  myself so maybe some good luck is with me, mind you it did take me some time to assert this!!

The only mistake i have made is that i purchased my broadband filters from Astronomik and then my NB filters from Astrodon...unfortunately the filter offsets between the broad and NB filters are quite wide but i auto focus and its o.k.

So thanks for the info Olly, at least i can now work out any issues that would make it a bigger job than it should be.

Ray 

[Martin-Devon]

Ray, I use my 106ED almost permanently with the reducer in place. The wider FOV and faster F ratio are big advantages. Mine is mated to a QSI690 and Ian King supplied a custom made spacer that gives the perfect spacing. I did have tilt in my imaging train initially and had to mess around a lot with the grub screws in the reducer to eliminate; once done though it seems stable. The focus is razor sharp at this F ratio (3.6) so Focusmax or similar is preferred, coupled to a motorized focuser ( I use a Lakeside). I do get temperature shift with temperature drop, but once the temperature settles it's very stable. For narrowband filters I do repeat focus runs on the nearest magnitude 5 star using CCD Commander + Focusmax.  

Martin 

[libraryman]

Hi Martin, iv'e just finished dropping you a PM, i hadn't read this reply from you, great news though, i can now look for one.

Ray