Field flattener suitability

[skyrunner]

I have just acquired a TS Optics 130mm refractor for imaging. I have a 0.8x FF for my TV-85, can I also use this with the new scope? Both scopes are f7. Or do I need to buy one specifically designed for the TS Optics scope? 

[fozzybear]

what brand of FF do you have and what model of TS scope is it  https://www.teleskop-express.de/shop/product_info.php/info/p12741_New-but--TS-Optics-PHOTOLINE-130mm-f-6-6-Triplet-FPL-53-Super-APO---3-RAP-Focusser.html the more info you can share the better

[michael.h.f.wilkinson]

A flattener is typically designed for a specific field curvature (well, obviously), and this means a particular combination of focal length and objective design. Usually they work well over a certain range of focal lengths given an objective design (like doublet or triplet). If you are well away from that range, it will probably be sub-optimal, or at least should be used at a different distance from the CCD than the nominal value. The focal ratio is less important.

[skyrunner]

The scope is this one https://www.365astronomy.com/astronomical-telescopes/apochromatic-refractors/teleskop-service-apo-refractors/ts-optics-photoline-130mm-f-7-triplet-apo-fpl-53-2.5-rack-and-pinion-focuser

and the FF is this https://www.firstlightoptics.com/tele-vue-telescopes/tele-vue-08x-reducer-flattener-trf-2008-for-tv-76-tv-85-and-400-600mm-focal-length-refractors.html