Bests & Worsts Reviews from Amazon

This lens is wonderful. It is one of the top rated nightscape lenses that is currently available on the market. Here is what I have found: Pros: 1. This lens is cheaper by orders of magnitude over similar lenses. To get a fast prime lens like this usually costs upwards of $2000, for a mere fraction of that price this lens blows away the competition. 2. Sharp. This lens has great optics and takes sharp pictures corner to corner by f/8. Wide open it is is a little softer in the corners, but that is just how it goes, unless you want to spend $5000 that probably won't change. 3. Almost no Coma or Chromatic Aberration. For those who don't know, coma is when points of light appear as streaks or smears. The only time this is really encountered in a practical situation is when you are photographing stars. Even on the much more expensive canon and nikon lenses the corner stars appear as ugly streaks, this lens has some of the best coma correction available Cons: 1. Fully manual. This may or may not be a con for you, but in the age of auto-focus, and auto everything, it certainly takes some getting used to. My first 20 pictures with this lens all looked terrible because I was focusing wrong and underexposing. Once I spent some time learning how to properly use a manual lens those problems disappeared. 2. Distortion. This is not really a good lens for architecture. There is rather significant mustache distortion in this lens. This can be corrected in post processing by finding the correct lens profiles online, but that is not ideal if you are photographing buildings and man made structures for a living. However that being said, if you use this lens for landscapes, nightscapes, or pretty much anything that isn't architecture then you will never notice the distortion and shouldn't worry about it. 3.. Focus scale is off. This is the only reason I gave this lens 4 stars instead of 5. From reading around this seems to be a common problem with these lenses. For some reason the focus distance scale is not set correctly. If you google this lens you can easily find a guide to correcting the focus ring and setting it to the correct distances. However upon doing this I found out that it is actually more subtle than just a wrong distance scale. With my particular lens I found that I obtained maximum sharpness for objects ~1mile away when I set the distance scale to between the 7ft and 10ft marking on the lens. This is quite a ways away from where the infinity mark is. However at night when attempting to photograph the stars, I found that I obtained maximum sharpness of the stars with the focus set slightly past infinity. Most of the time one would expect that 1 mile is essentially infinity when it comes to lenses, but for some reason there is a huge difference between 1 mile and infinity. Once I conducted enough tests and examined the test shots at 100% I was able to use simple masking tape to re-label my lens for the correct positions for various situations. It should be noted that this is really only an issue if you are shooting wide open at f/2.8. By f/8 everything will be razor sharp and in focus no matter where you set your focal point due to the enormity of the depth of field of such a wide angle lens.