Wide angle lens?

Started Jan 15, 2014 | Discussions thread
(unknown member) Senior Member • Posts: 1,324
oh dear...

brightcolours wrote:

canonagain123 wrote:

the samyang 14/2.8 distortion, including the perspective distortion, can be corrected PERFECTLY, down to the last pixel. this works on JPG and RAW the same.

Nonsense, you lose pixels correcting CA, AND you lose resolution on pixels you have not lost.

CA can be corrected for RAW quite easily, but it can sometimes present a problem. That correction can lead to some lost image information too, if the CA is bad.

Nonsense, you never lose way less "information" correcting CA, you actually gain sharpness and contrast (you restore information).

CA and a little distortion can be more of a hassle to correct than a lot of distortion with the perfect lens profile. If you know you'll never shoot JPG with the lens, then it's not a worry. If there's a chance that you'll want to take even one JPG picture with it, you might be pursuaded by the lack of CA and easy distortion/perspective correction.

It is the same with JPG, one can correct CA in exactly the same manner as in RAW.

You understand that perspective distortion correction means that some objects will be made larger, some smaller, right? In the case of making objects smaller (from 100px to 50px width, for example), they were too big in the first place, so they lose 75% of their pixels. In the case of making them bigger, the new pixels are interpolated (the new algorithms are good) from the original pixels. You win some, you lose some. In the end it's a zero sum game.

It's impossible to make a FF 14mm with no distortion. It doesn't matter if it's branded Samyang, Canon, Nikon, or Pentax. It doesn't exist. There is only "less distortion", not "no distortion" The distortion even exists in the human visual system, but is ignored/corrected in the brain so you never experience it. It's not a matter of brand X vs brand Y, it's a matter of physics. You can't project a 180 degree hemisphere onto a 2-dimensional rectangular surface and get no distortion. Whatever the distortion is, if you correct it, you "lose" some information, but it may make sense if you think of it this way: if the distortion is not desired, 100% of the original information was useless anyway. The resulting information from a perfect distortion correction is the most you can physically get out of the scene with today's technology, at least out of any sub-$50k technology.

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