I have an old EF Rokinon 14mm f/2.8 that I have played around with astro over the years. Have some decent images but never had the time nor location to get more into that type of photography (big city light pollution, no stars, northern hemi etc). At the time this was the cheap go to astro lens, so I never felt bad about it not be used much and just kept it around.
Fast forward a decade or more: I will soon have some time in one of the dark sky areas, so wanted to have more of a play with astro given the area. I dusted the Rokinon off but I also now have the RF14-35L which is obviously a stop slower.
Does the Rokinon stand up against the RF 14-35?
I'm concerned about the stretching that happens on correction even on the RF L lens - should I be?
I know 2.8 vs 4 is an issue but not sure it's that critical but happy to be convinced.
You can definitely shoot Milky Way photos with an f/4 lens, it just requires shooting at a higher ISO. As far as I'm concerned, using the gear you have is the best way to decide if investing more time and money into astro is something you want to do.
The extra stop of light on the Rokinon 14/2.8 along with its ability to control coma in the corners at such a low cost is why it is (was?) popular for astro use. Of the two lenses you have, that is where I would personally start. I've never tested the 14-35/4 for coma so I don't know how it performs in the corners. Overall image noise will depend on what camera you use. I used to shoot the 17-40/4 on the 6D and that body could handle ISO 8000 without much trouble.
If you decide astro has become something you love, then there is plenty of new gear you can get!
