pardon my intrusion here Mikael, but the words and concepts you are using in the above is not under question. WHat is under question is the posts where you say that the HTP causes half the number of photons to reach the sensor.
Not at all.
what I meant was that (and I hope I use the right words now so you all can understand me) that the camera is metering at 200iso and also exposed after 200 iso , 1 stop less/shorter than base iso 100 = shorter time or 1 more f-stop..
At 200 iso there are already created" a head room," se my picture,it is old and used many times, the sensor charge/electrons i now halved compare to 100iso .And for every iso stop there are a halving (se the picture)
In a regular 200iso exposure this head rooms are then analog gained "200iso"
In HTP the gain is "100 iso" and to created a headroom for adjustments and another smoother curve.
The same thing as under expose 100iso one stop and then adjust the raw file with own curve etc in the raw converter.
ok, but I have to ask the obvious question: you are offering this as a general explanation of how HTP works at all times? when someone asks what happens to their camera when they turn HTP on, you going to tell them that half the photos reach the sensor without asking them where they have already set the ISO dial?