11-08-2017, 05:55 AM
(This post was last modified: 11-08-2017, 05:59 AM by Brightcolours.)
Measuring T-stops is actually not that simple. How do you propose to go about that?
Camera sensors contribute to the light loss an image would try to reveal, microlens design and pixel size may contribute to that and vary from sensor to sensor.
Cameras also "cheat" by applying extra gain to the signal with larger apertures, due to that sensor level light loss. Do they apply the same gain with lenses from other manufacturers, which to the camera may identify wrongly?
Lenses may also show varying light transmitting through the focal range, or not.
Buy larger aperture lenses primarily for more shallow DOF possibilities, and worry less about 1/2 of a T-stop more or less.
As to how effective IS is... That is pretty hard to establish in an objective, consistent way. In which use cases? And it should be done by a machine test rig which assures the same conditions for every lens, review to review, through the years.
Camera sensors contribute to the light loss an image would try to reveal, microlens design and pixel size may contribute to that and vary from sensor to sensor.
Cameras also "cheat" by applying extra gain to the signal with larger apertures, due to that sensor level light loss. Do they apply the same gain with lenses from other manufacturers, which to the camera may identify wrongly?
Lenses may also show varying light transmitting through the focal range, or not.
Buy larger aperture lenses primarily for more shallow DOF possibilities, and worry less about 1/2 of a T-stop more or less.
As to how effective IS is... That is pretty hard to establish in an objective, consistent way. In which use cases? And it should be done by a machine test rig which assures the same conditions for every lens, review to review, through the years.