lighthouse Loc: No Fixed Abode

I did my first Milky Way shoot shoot last night to have a play.
I tested/played with 3 lenses.
I have a 5D2.
Lenses used
17-40mm F/4 @ 17mm
50mm F/1.4
100mm non-L macro F/2.8

I was pretty clumsy and the focus is a bit iffy. Seemed to be a lot of water/moisture in the air. Not clouds, just lack of clarity.
I use live view, 10x zoom to focus on one star in manual focus.
The thing that struck me was how much easier it was with the F/1.4 than the other lenses - even compared to the F/2.8.

The shots that I want to take are wide landscape shots with the Milky Way as a back drop.
I do not want star trails.
I want exposures of 10-25 seconds.

So this led me on a search for the widest ultrawide.
IE the widest lens with the widest aperture.
The options seem to be out of
Canon or Sigma 15mm F/2.8 fisheye.
Rokinon 14mm F/2.8
Canon 24mm F/1.4
Sigma 20mm F/1.8

Any opinions on these lenses?
Are there any other lenses that I should consider along these lines?
Thank you in advance.

St3v3M Loc: 35,000 feet

Great detail in your question.

lighthouse Loc: No Fixed Abode

Thank you Steve. Just a shame no one could be bothered answering.

Bubu Loc: Out of this solar system

I would suggest you go to different astronomy/astrophotography forums; look at the photos Similar to the ones you want to take and ask questions there. The forums i belong to are "stargazers lounge" or http://stargazerslounge.com AND cloudynights.com. They are very cooperative and like to share information. You can check the galleries and ask the authors about their photos. Good luck!

lighthouse Loc: No Fixed Abode

Thank you very much Bubu.

gekko11 Loc: Las Cruces NM

hello lighthouse, I use a canon 5d mk II and mkIII with a 15mm F/2.8 lens and i'm pleased with most of the results. the time limit for exposure seems to be about 30 sec. before trails start to become noticable . 20 sec is better , depending on how close the scrutiny is. You can stack photos with mac or pc using Stark Labs Nebulosity, it's great! the only drawback i've noticed with canon 15mm lens is color aberration towards the periphery , but its not really noticed unless magnified.. I would love to try a 1.4 ... hope this helps

lighthouse Loc: No Fixed Abode

Thank you gekko. I ended up buying a Rokinon 14mm F/2.8.Haven't been able to test it out yet. Its been cloudy for the 8 days since it came.

IR Jim Loc: St. Louis

There is a nifty chart that may help you decide. There is also plenty of other good information in this article.

http://www.davemorrowphotography.com/p/tutorial-shooting-night-sky.html

FotoBuf Loc: Arizona

Ken Rockwell gives some advice on his web site, kenrockwell.com. The wider the lens, the longer the exposure can be without showing star movement. You might try ISO 1600 to 3200 to start. Also a setting of Incandescent gives a nice deep blue sky. I used these settings last month with a 50/1.8 lens and was happy with the results.