In 2016, Steve posted a video about whether better to use 1.4X TC or to crop to DX in the Nikon DSLRs.
https://backcountrygallery.com/comparison-test-crop-camera-vs-1-4x-teleconverter-full-frame/
His conclusions were that TC always causes some loss of sharpness and therefore sharper results when cropping than when using DSLR. For example using a 20MP cropped sensor camera was better than using a 20MP full sensor camera with TC.
My impression was that if using an FX sensor camera, if it is 20MP and cropping reduces size to 12 MP, then using TC is better than cropping. But if it is 40+ MP sensor and cropping reduces size to 20MP, then cropping is better than TC.
Now with the new mirrorless cameras, the Z lenses and teleconverters are better than the older F-mount lenses and TCs.
I would love to see some testing (or maybe I'll try doing the testing myself) to see if it is better to use a TC or better to crop to DX. Especially with a high MP camera like the Z9.
https://backcountrygallery.com/comparison-test-crop-camera-vs-1-4x-teleconverter-full-frame/
His conclusions were that TC always causes some loss of sharpness and therefore sharper results when cropping than when using DSLR. For example using a 20MP cropped sensor camera was better than using a 20MP full sensor camera with TC.
My impression was that if using an FX sensor camera, if it is 20MP and cropping reduces size to 12 MP, then using TC is better than cropping. But if it is 40+ MP sensor and cropping reduces size to 20MP, then cropping is better than TC.
Now with the new mirrorless cameras, the Z lenses and teleconverters are better than the older F-mount lenses and TCs.
I would love to see some testing (or maybe I'll try doing the testing myself) to see if it is better to use a TC or better to crop to DX. Especially with a high MP camera like the Z9.