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Replace Canon 100-400 V1 by tamron 150-600G2, good choice?

Started Apr 2, 2018 | Questions thread
John Sheehy Forum Pro • Posts: 26,698
Re: Too Wide Focal Range...
2

Yeant wrote:

Ok thank you, it seemed to me that the tc was losing the af and a lot of IQ

TCs generally lower the "IQ" of the whole frame, or the pixel-level look, at least a hair (except that they may improve sampling by reducing aliasing), but that is not necessarily a subject-quality, or "final IQ" loss, and often a gain in multiple ways.

This may surprise some people, but a TC can actually decrease subject-level noise, especially in cameras with blotchy or banded noise. This is even more true now that there are cameras where at some point going from one ISO to the next one 1/3 stop higher actually reduces pre-gain (high ISO) read noise by about 50%, which the TC may actually force, indirectly, with the same shutter speed, but a higher f-number. On cameras with AA filters, the TC forces more of the lens' analog resolution to get through, meaning you can sharpen less, resulting in less added noise from sharpening.

Cropping instead of using a TC is usually only beneficial when the TC would make the FOV too narrow to be useful, or the TC would have caused focus to be missed.

Higher ISOs with higher pixel noise and softer pixels from a TC are not real problems; they are imaginary problems, unless that pixel softness is coming mostly from the TC, rather than from the lens, but magnified.

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