Agree Peter. The head cloth was an important accessory in single stack. With the extra filter it becomes the most important accessory of all - getting your eyes accustomed to the slightly dimmer image is paramount. Like Jabeoo, I have been through a big learning curve with the Lunt - documented elsewhere on this site - it took several weeks and lots of experimenting to get the most out of single stack, but my expectations have been exceeded with DS since the unit arrived last week. From the start it delivered greater contrast and detail on the solar surface, and stunning depth to filaments, which now look like egg white floating in hot water. Active regions are transformed, although as yet the sun hasn't been particularly active. All this while retaining the same clarity of proms provided by SS. The sweet spot for me is larger with the extra filter, though not by much. These are only early impressions. Who knows, with jabeoo's suggestions above there may be even more performance to squeeze out of these wonderful scopes. I'm looking forward to some clear skies this weekend - will also be my first chance to test the Leica zoom on the Lunt and see how it compares to the excellent Pentax.