Williams adjustable flattener for 132 Wednesday, 6 May 2020 | Terry
Excellent, less vignetting, rounder sharper stars than all other flatteners I have use with other telescopes and flatteners. Again along with the whole industry astronomical industry some important innovations are glossed over or buried. So question can you include a filter within this flattener. and the answer is yes. An excellent flattener, particularly if you do one shot colour astro photographer and require a single light pollution or other filter. Expensive but makes imaging through this flattener and setting up is simple and quick.