Do we still need a TC?

Started 10 months ago | Discussions thread
Ontario Gone
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Re: Do we still need a TC?
In reply to Anastigmat, 10 months ago

Anastigmat wrote:

Mark Ransom wrote:

A teleconverter works by magnifying the image that it gets from the primary lens. You could get the same effect by simply cropping, but the assumption is that the magnified image will be higher in quality than the cropped image. For a high-quality primary lens coupled with a decent teleconverter this has been the case until now. But with the introduction of the K-3 at 24MP with no anti-alias, have we reached the point where cropping can do just as good a job?

I'd love to hear from someone with both the K-3 and a decent TC to do a direct comparison.

Packing more pixels onto the same sized sensor does not actually give you higher resolution. It just gives you larger files.

You are talking about equivelant resolution, where certain technical flaws cause the photo to look as though it were a lower resolution than it is. While this is true, it only happens to the degree of the weakest link, be it noise, motion blur, lens flaws, or even lateral and spherical CA to an extent. Your statement about more pixels is wrong though, otherwise we would be just as well off with a 2mp sensor. If you are looking at files only in full view and only on a 1080 screen, yes, they would look pretty much the same with 2mp vs 20mp. In this world of digital virtual resolutions, it's not that simple. Many people crop, a lot, I would even call it a fetish. Many people print large. Some people have 4k TVs. If you can avoid diffraction, and with better glass, more MP does equal more resolution, but this is nothing D800/E users haven't been dealing with for a while now.

How much resolution you get depend on how good your lens is, and also on diffraction.

If you stop down your lens to f/11 or smaller, your resolution is limited to a few megapixels even if you have a super duper lens that can resolve over 100 line pairs per mm.

lens resolution has nothing to do with diffraction, a bad lens simply adds fuzzyness to an already soft photo. Imagine looking through one dirty window, that's diffraction. Now imagine looking through 4 dirty windows, that's diffraction+motion blur+poor lens rez+lots of noise. They are however not mutually exclusive.

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