Hi guys. Just a note about the Combo Quark.
Yes it is more versatile than the Original Quark.
Those who are capable of manipulating focal ratio will enjoy its flexibility.
There is one bonus / trade-off between the two which everyone may want to contemplate.
Because the blocker on the Combo Quark is bigger, a larger focal length solar image can pass through it.
For example, a 90mm F/6 = 540mm using an Original Quark cannot pass a full disk.
But a 90mm F/6 = 540mm using a 4X powermate, then a Combo Quark will pass a full disk.
The barlow costs more, but one can pass a larger disk with a larger blocker behind the barlow instead of in-front.
However, the Original Quark in side-by-side comparisons will yield slightly higher contrast.
This is due to the optimizations specific to telecentric H alpha of the Quark barlow, the extra intra-lens knife-edge baffles and the nature of pupil vs focal plane light.
We offered the Combo Quark for the slightly advanced observer who can do a little math and compute focal ratios to figure out his best application.