FIRST LIGHT
arrangement felt a little imprecise. Although we could get to what looked like perfect collimation, even gentle application of the locking screws could mess this up. Our best and most precise results were obtained by collimating on the fly before each session. Fortunately, the large adjustment knobs on both primary and secondary mirrors made this a fairly easy task.
Finding focus
While image testing, as well as the expected diffraction spikes from the scope’s four-vane spider, other diffraction effects appeared too. Bright stars were surrounded by ‘light-sectors’ interrupted at 120 intervals by ‘shadows’, presumably caused by the three sturdy clips retaining the primary mirror.
The PN210 Mk II uses a 2.5-inch Hexafoc Deluxe focuser with a larger than usual opening to reduce vignetting effects. The focuser also offers a 10:1 speed-reduction knob to help you achieve final, accurate focus. The main body of the focuser feels robust and can be adjusted in terms of focuser tension. But once focus has been achieved, there’s no facility to rotate an attached camera. There are thumb and grub screws near the focuser base but no mention in the instructions as to what they’re for. Speaking of instructions, we were disappointed to see that those supplied with the PN210 Mk II were for the Mk I model.
The PN210 Mk II is a portable grab and go scope. Its fast, f/3.8 optics allow you to go deep with relatively short exposures. But it still feels tricky to get and hold collimation – an essential element to a fast Newtonian. There’s also the question of whether a field-flattener should have been included, given that it is a photographic Newtonian; without one, there’s coma visible and an interrupted radial diffraction pattern around bright stars. Great shots are possible with patience – but it takes a bit of careful tweaking to get the best results.