Using comparisons to film day 35mm cameras with respect to lenses makes going from one sensor size to another as well as respective lenses easier. It merely serves as a reference point. In short, the work was already done for digital photographers. Whether the 35mm film lens reference is the best choice, is perhaps another topic.
If you have 4/3 camera and then got a full frame (as some call it) and then a medium format, do you really want to go through an exercise of comparing them all to each
other or simply have one reference point (which in this case happens to be the 35mm film camera lenses reference)? I'll choose the single reference because I am both lazy
and smart.
Using T-stops instead of F-stops is for me a rather silly exercise. F-stops remain reasonable as it is a generic equation that traverses the entirety of photography while T-stops deal with flaws in light transmission of a given lens (it is a measurement). If I only had 1-3 lenses and that is all I had, and had to be super critical of exact spot on measurement of light hitting the sensor, then perhaps a T-stop reference makes more sense. Then again, are sensors even among a given make/model of camera 100 percent the same in sensitivity? Answer is perhaps close enough but not 100 percent all of the time. Or perhaps you got a model/make of a camera and then moved up a model where the sensor is not exactly the same. T-stop tells you nothing...absolutely nothing unless you measure it against the sensor you plan to use. The full value of the T-stop remains with measure the light transmission of the given lens WITH the actual sensor. I'll just say the T-stop actually had more value with shooting sensitive film in larger format where both film and print didn't have as much flexibility and even that was quite rare in the golden days of film photography. Btw, for those that use light meters, you would have to make/buy special filters to adjust for the light transmission of your given lens when you use it if you want the "T-stop" on your meter. Again, utter nonsense.
There are a lot of terms I don't like and I have simply adapted to using them. Though I obviously came from film days, I do get with the plan and understand that digital photography is quite a different breed (as are many of the younger photographers) from film photography.
