Taken just before midnight 4-5/8/2018, I tried using EZCAP software but then found that Nebulosity 4 gave better images. There was no interlacing effect with images of Vega through the Skywatcher 120mm DS Pro refractor up to 6 seconds in length (I presume because camera is not receiving > maximum tolerated amount of light). Even though the scope (on EQ6 Pro) was not properly aligned, it tracked sufficiently to keep the star in the slit for 6 seconds or longer.
The EZCAP-based calibration file gave incorrect wavelengths on the graph so I resorted to using the Nebulosity-based calibration file from 29/7/2018.
My spectrum clearly shows the Hydrogen Balmer series of lines.
Compare to this typical spectrum of Vega from http://ksu-astro.nckas.org/spectroscopy.html
Or this one from http://www.astrosurf.com/buil/us/vatlas/vatlas.htm