Why does Zeiss manufacture only manual focus lenses?

Question

I've heard that Zeiss's quality is very good/great but I'm also curious if it has anything to do with the "manual focus only".

I have read this question but it only partly addresses my question. Is it a company policy or what?

Answer

It is one of the lens design compromises they have chosen to make. While I don't think anyone can know for sure the reasons behind that decision, I can think of several likely ones:

• Zeiss's own most successful cameras are rangefinders, which do not auto focus. These are the only cameras they still make today.
• MF lenses avoid any complication from integration with an AF system, keeping the lenses smaller.
• Major SLR companies do not license their lens mounts. Companies like Sigma and Tamron reverse engineer the electronic communication protocols. Making an all-manual lens avoids this need — although recent Zeiss lenses do feature electronic coupling for aperture.
• It makes a niche, since lenses designed for MF are usually better for that purpose than those designed for AF. Good MF lenses have a long "focus throw" — you turn the focus ring a large amount to make a difference, allowing fine adjustments. AF lenses, on the other hand, are designed for smaller movements to optimize AF speed.

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What makes a Carl Zeiss lens so special in a smartphone?

Question

There are smartphones on the market that have a focus towards photography. Some are equipped with a Carl Zeiss lens. I have looked into Wikipedia, which tells me that they are a brand who produces lenses. What makes their lenses so special?

What do you think about a 5MP camera in phones, one which is branded Carl Zeiss, versus another one which isn't? The device I have in mind is the Nokia N900.

Answer

Carl Zeiss is a very well respected lens maker, and very literally one of the reasons "German engineering" conjures images of precision and care. Camera phone manufacturers license the name (and, maybe but not necessarily, actual lens technology) from Zeiss in order to borrow some of that high-end image.

This isn't necessarily all chicanery: companies who are doing this are at least somewhat interested in appearing to be high quality, and the name isn't completely diluted, so you have a reasonable expectation that if the lens says Zeiss, it's probably above run-of-the-mill.

In the case of the N900, the lens is quite good for a smartphone, and more importantly, the sensor is relatively large. 5mpix is a decent resolution for that size of sensor — at this point in the technology, you're not going to get a lot out of having more.

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