reducing a petzval?

[blink138]

hello members
i want to know if it is possible to add a reducer or extender to the quad designs as in the petzval?
reading about the new vixen f3.8, and a note at the end says that there will be a reducer and extender being developed for the system.
any experience out there?
thanks in advance
pat

[RickS]

Tak has reducers for the FSQ refractors. They are Petzvals.

[blink138]

good point rick!
i suppose an aftermarket one could be more hit and miss without a proper factory unit
pat

[Wavytone]

You can add a reducer or compressor, however it will be complete guess as to the resulting field curvature and distortion. Might be tolerable, might not be. You take your chances.

Chromatic aberrations coma and astigmatism should be ok.

[LewisM]

My Vixen DED108SS is a 4 element Petzval Nagler astrograph refractor. It is f/5 natively. I wonder how fast I could go? (120 sec exposures even cause blooming with the CCD currently at f/5)

Now you have me contemplating making it f/3 or so... but then I may sacrifice the field flatness :) (perhaps my collimation I did recently is still a micron off)

[gregbradley]

My experience with reducers is they occassionally can be used on other scopes often with less than perfect results though. For example I used a 4 inch Tak FS152 reducer on my TEC180. It worked on most of the field but the corners had some coma. That was with a 16803 chipped camera so it was a torture test.

I have great results from a TEC160 using an AP155 telecompressor. I plan to get an adapter for my TEC180 using that. It has 1mm+/- tolerance though so it has to be exact.

APM make a Riccardi reducer that is supposed to work on many scopes. Perhaps drop a line to them to see if they would recommend it for your Vixen.

There is also a small possibility the Tak FSQ reducer would work but I doubt it. It would not work on the FSQ106N and it sat inside the tube with a bucket type adapter. So you'd have to see if your Vixen would allow that sort of adapter. The rear element may be in the way. I think this is the main issue with Petsval - the rear element often is right near the end of the scope and may not take a reducer as Petsval in a way already has a reducer built into it.

Greg.