Do we still need a TC?

Started Nov 11, 2013 | Discussions thread
MightyMike Forum Pro • Posts: 37,794
Re: Do we still need a TC?

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. 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. Resolution aside, the greatest obstacle to sharp images when using teleconverters and long lenses is focusing accuracy. If your lens is f/5.6, a 2x teleconverter requires manual focusing, Unless you focus correctly, you won't get a sharp image.

Considering very few, almost nobody will use a 2x TC on an F5.6 lens then that is not the greatest obstacle, in fact a much bigger obstacle is trying to shoot through too much atmosphere, that can degrade IQ far more than A) a TC or B) diffraction.

Also of course one can now CDAF an F5.6 lens with a 2x TC, i think Ron successfully CDAF'd an F71 setup on his K-01

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Mike from Canada
"I am not a great photographer! God is a great creator! All I do is capture His creation with the tools He has provided me."
'I like to think so far outside the box that it would require a telephoto lens just to see the box!' ~ 'My Quote :)'

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