01-19-2022, 03:28 PM
(This post was last modified: 01-19-2022, 04:24 PM by Brightcolours.)
The IQ loss one at least should expect is dividing the resolution by the magnification factor the TC offers. So, a 2x TC always will halve the resolution of the lens. It depends on how sharp the lens is, and the resolving power of the sensor, on how one would rate the results...
Any (not ancient) TC consists of a number of elements that all work together to crop the image without introducing (too) much CA, distortion and so on. So, it is not as simple as just sliding an extra lens element in the optical path. 2 TCs, as you seem to suggest, would want to live in the same space....
As such, it can't be made smaller... And making a 20mm lens into a 50mm lens makes for the need for a 50 / 20 = 2.5x TC... That means more than halving the resolution. How will that provide better IQ?
Also... a TC lowers the F-stop. 20mm f1.8 + 2.5x TC = 50mm f4.5 .... (and of course a 35mm f3.2 in between)
(01-19-2022, 01:56 PM)thxbb12 Wrote: Speaking of TC, how about generalizing the concept further?
For instance by building a 3 focal length lens, e.g. 20-35-50 f1.8?
I guess it could be made smaller than a zoom while providing better image quality?
Any (not ancient) TC consists of a number of elements that all work together to crop the image without introducing (too) much CA, distortion and so on. So, it is not as simple as just sliding an extra lens element in the optical path. 2 TCs, as you seem to suggest, would want to live in the same space....
As such, it can't be made smaller... And making a 20mm lens into a 50mm lens makes for the need for a 50 / 20 = 2.5x TC... That means more than halving the resolution. How will that provide better IQ?
Also... a TC lowers the F-stop. 20mm f1.8 + 2.5x TC = 50mm f4.5 .... (and of course a 35mm f3.2 in between)