Visual astronomer here who has never had a need of a field flattener, hence the possibly unsophisticated question...
I've acquired a gorgeous William Optics FLT 132 refractor from a deceased estate. It's a scope that would take some extremely pretty pictures if I were to go down that route.
William Optics have a few field flatteners and reducers which they promote as compatible with the scope.
https://www.testar.com.au/products/f...56-gt102-gt153
https://www.testar.com.au/products/f...-flt132-flt156
https://www.testar.com.au/products/f...-flt132-flt156
Question: are field flatteners very specific to specific makes and models of scopes, so if I need a field flattener I should buy the WO one, or would there be a variety of models I could choose from?