Here is a picture of AR12396 on the best setting (which I discovered later). This image was very popular after being posted on Flickr Explore and managed 7,500 views, I was quite proud of that :)
So, now for the testing, the Quark is a temperature controlled etalon made from mineral mica crystals. So, to achieve hydrogen alpha centre-line we need to get the temperature exactly right. To start I set the Quark on zero point which is 12 o'clock on the dial (middle) and bagged some images of the AR and filament and prominence, although like previously I really struggled with the prom exposure. I then started turning the dial clockwise to +01 and waited for the green light to come on (about 5-10 minutes). Now I knew this position was better (more on band) the last time I had used it but this is all I had managed. I then kept imaging the same 3 objects on the same exposure (no flats) for every point on the dial clockwise to +05. I then turned the dial all the way back to -05 counterclockwise and took the same images again each click until I got back to centre point again. So here are the results, I think the best overall contrast, flatness of field, and prom exposure was +04 clockwise. You can see that 'on band' comes in from the bottom right, passes through the middle then leaves top left, just like a tilt tuned etalon, this surprised me, somehow I expected it to be like a pressure tuner with an even field. Now I know why I had been struggling with the prominence on the first two outings. I think it is very important for each Quark user to try this out at some point if they can, especially if you have a problem with uneven field or struggling to see prominences. If you spend a lot of money it is worth getting to know the beast you bought.
Here are 3 image series - active region, filament and prominence to show the different dial settings. The setting -05 is clearly in the blue wing.
As an aside to the testing it was very interesting to study these regions in the blue wing of hydrogen alpha line (-05). I could tell it was the blue wing due to the spicule 'twinning' which is only seen in the blue wing.
Bright Arch filament footpoints - not to be confused with Ellerman bombs!
Ellerman bombs (only distinguished from footpoints if you take a series of images)
A prominence showing the blue shifted parts and blue shifted spicules (blue shift=moving quickly towards you).
So plenty of fun can be had using any of the dial settings but it is seriously worth knowing where hydrogen alpha centre-line is on your model of the Quark. All will vary because of the natural mica that the etalon is made from and the temperature and pressure at your location.