Yes, Cometcatcher, my 183 is the cooled colour version. So it looks like the Esprit 100 and the 183 are the way to go. I thought that must be the case, and the Esprit has the flattener, AND... I have got the filter box in the optical train too, so can experiment with the Baader Nebula filter, OIII and sulphur job. And later, I will have a go using my secret weapon, the 1600-MM and LRGB filters