ZWO Narrowband 7nm OIII,SII & Ha Filter Set - 1.25" - NB7NM1.25 90mm refractor The mount base includes a

The mount base includes a small polar alignment tunnel that allows users to roughly align their observing setup with Polaris

you will always have an optical alignment which is as perfect as it was on the first day you got it

135 mm (from M54x0

37 arcseconds Resolution (Dawes): 1

It has a focal ratio of f/4

ZWO Narrowband 7nm OIII,SII & Ha Filter Set - 1.25" - NB7NM1.25 90mm refractor The mount base includes aThis Narrowband Filter Set from ZWO, also known as a SHO Set, is used for tri color astrophotography to give you beautiful "Hubble" type results. The three piece filter set includes a 7 nm OIII, SII & Ha 1. 25" threaded filter. The glass thickness is 2. 0+ 0. 03 mm, and the overall thickness of the filter is 5. 5 mm plus 2. 5 mm for the M28. 5 x 0. 6 male threads. The ZWO 7 nm bandpass is designed for imaging nebulae. H Alpha (Ha) Filter The ZWO H