Just to make the point, the reason I do not own a Rokinon lens, and I currently have some 40+ lenses, is that simple reason. I do not want to deal with the hassle of getting that good one. You buy a Canon lens and you get a perfect one. Period, end of story.
In my circle of friends there are several Rokinon lens owners. The Rokinon lenses they use and own are top notch. Very good and extremely sharp. I hate to say it but they are probably better than my Canon rival lens. However, none of them, not one, got that lens on the first try. They all got returned and/or replaced. Sometimes several times.
I will most likely buy a Rokinon lens, eventually, as the curiosity is just too much for me to handle. 
It is a disease, I know. I am addicted to lenses. 
There, I admit it.
It will be from B&H as I know they will take it back and replace it without hassle.
"I have found a Rokinon 14mm T3.1 ED AS IF UMC, ..."
Just my .02 cents but I would never buy a used Rokinon unless I could put it on my camera and try it. I mean really TRY it.
Rokinon's QC is so bad they produce some of the biggest pieces of crap you can imagine. But, always a but, isn't there? They can make some truly fantastic lenses. You have to use them first to know.
You can easily see that a used Rokinon, that one, could just be one of those, let's say less desirable pieces of ----!
OK., maybe that was .03 cents worth. 
@UncleJoe wrote:
One other thing that I have been considering is a star tracking device I have not seen any questions on this forum about them, should I start a new topic or is it proper to bring that up here?
The two most popular tracking heads are:
1) The "Star Adventurer" by Sky Watcher
2) The "SkyTracker Pro" by iOptron
The Star Adventurer was the beefier system and could handle heavier loads and costs a bit more... but I noticed that NOW Sky Watcher offers a "Star Adventurer Mini" (a lower cost version that handles less-beefy loads) and conversely iOptron now offers a "SkyGuider Pro" which is a more expensive version to handle beefier loads. So both companies are definitely trying to cross-compete both on load capacity and price.
These devices tend to be in the $300 price range (give or take a bit).
The Earth spins from west-to-east which gives us the illusion that we remain still and the sky moves east-to-west. The tracking head spins east-to-west and while it has selectable speeds, the main speed for tracking stars ("sidereal rate") rotates at 15 arc-seconds (angular rotation) per second (of time).
If the rotating axis of the tracker is exactly parallel to the axis of the Earth, then the rotation of the device cancels out the rotation of the planet and any objects in the sky are exactly held in place ... you can take nice long exposures with tack sharp results.
The shot below used a 135mm lens and an 8 minute exposure!! The lens was set to f/10. This isn't the exposure I actually used when imaging the area but it was nice to test the tracking accuracy (the real exposures used a much lower f-stop and much shorter exposure times.) ...but you get the idea. A nicely aligned tracking head will eliminate the star drift problem and not only let you shoot longer to capture more detail... it'll also let you use longer lenses for more detail on parts of the sky.
These heads all come with some type of alignment aid to help you get a pretty close polar alignment.
I do strongly suggest a quality beefy tripod. You may want to hang a weight from the center post to help stabilize the tripod. Adding weight helps reduce vibration.
I think the iOptron might include the equatorial wedge but I think it's sold as an accessory for the Sky Watcher brand head. Regardless... you want one. The head gives you fine adjustment control for carefully dialing in your accurate latitude and azimuth for accurate alignment. It can be done with just a simple ballhead or pan-tilt head... but it's tought to do that accurately.
Both have an optional counterweight bar and weight ... which would be for use with longer/heavier lenses. This allows the weight of the camera & lens to be balanced by the counterweight so that the tracking motor isn't running slower when "lifting" the camera and faster when "lowering" the camera.
The narrower the angle of view of the lens, the more critical it is to have accurate alignment and tracking.
