when shooting milky way at night sky, usually using a wide angle lens. Of course you can use 85mm f1.4 lens, a telephoto lens renders stars larger and provides a different look to a night and it just different view like astrophotography. You can't capture foreground interest and you probably do not want to exceed roughly 5 seconds exposure at 85mm ^^

A simple rule of thumb to use for determining the longest exposure time that can be used without star trails becoming problematic is 600/(focal length). By this formula, a 14mm lens requires a 43 second or shorter exposure. An 18mm lens requires 33 seconds or less and 24mm can use no more than 25 seconds.

I think take panoramic shots of milkyway & stitch them together. You'll get gigantic super wide angle shots of milkyway.

Taken at Kuala Kubu. One of my friend's took this and i edit 3 horizontal panorama then stitch together.

by using rear curtain sync mode is one of the creative techniques at your disposal when you work with flash. Basically, the flash fires off towards the end of an exposure, or just before the rear/second curtain closes. With this technique, you can produces some really cool-looking blur and light trails while your subject remains in focus.

Here i'm setting flash at ground rear sync for the selfie with milky way. This is single shoot.


Image:- IMG_1836.CR2
Metadata:- 30sec, 16mm f/2.8, ISO3200
Flash:- Did fired at rear curtain
Lens:- EF1635 f/2.8L
Camera:- EOS 5D MkIII