Instruction: Answer the given question using the supporting document.

Input:
Question: I'm thinking of buying this lens for the A7s, but I have read about it's manual focus issues. Someone said that it is impossible to focus manually..??
Document: I had read the reviews, some of which had been to some extent negative. However, I have found that the lens performs quite well. It is sharp throughout its range&#8212;from a practical perspective and nitpicking notwithstanding&#8212;and has great color rendition without any noticeable CA. Others have found fault with its slow auto focus in low light, but at F4, this isn't a low light lens. Out in daylight it does just fine.
I ordered this lens as soon as announced. Before it arrived I had read on line some very mixed reviews from the usual technical sites and was disappointed to see the negative assessments. I thought of canceling my order but decided instead to get the lens and test it for myself.
After reading many mixed reviews of the Sony SEL2470Z Vario-Tessar T* FE 24-70mm F4 ZA OSS lens I decided to take a chance and purchase it from Amazon to use on my Sony A7r. You may read reviews with complaints of soft corners in pictures and slow focusing in low light. Depending on what your usage of this lens may be, this could be an issue for you. I use this lens for street photography and family photos. The pictures are very sharp and the OSS is a plus!
For this reason I recommend shooting with shading correction off in camera, and correct it in software on computer which does a better job. This might only be visible in say a snowy landscape shot where the white makes the colors shifts obvious. There is no noticeable field curvature at 24mm, center focus was best for corners as well.
Update: This lens appears it might have been designed for Sony A7s (newly released 12 MP camera).
Everything you have read about this lens is true! It's not as prefect as a 2.8 would be but it's as good as any 4.0 is!It's my walk around lens and has not dissapointed.
They just look special, unique, different. I wish I could better explain it, but after years of doing photography, and owning A LOT of lenses and cameras, I can honestly say that Zeiss lenses stand out when it comes to build, feel, look, and image quality.Having said that, I don't particularly think that this Zeiss lens is one of the best ones I've used. Nope, this is perhaps my least favorite Zeiss lens. Why?
There is noticeable field curvature at 70mm, so focus corners or center depending on your subject.What is worst about this lens is the corners are pretty flat, even stopping down. Most lenses are bad wide open and that is to be expected in the corners, but most improve by f/8. This lens doesn't. F/8 and 24mm hardly looks any different than f/4 and 24mm.
I would highly recommend this lens and the A7.
I am not saying it is a bad lens, just that the price doesn't match the performance. I wouldn't say it is better than the kit 28-70mm (good copy).
Answer: Manual focus?  Not impossible. That said, it is difficult to focus manual at extreme wide angle where autofocus does an admirable job.