Mikael here is the confusion
1. Your latest post is correct, i.e.QuoteHTP is nothing else than while the camera metering for 200iso the gain is smaller (around 100iso gain) and thereby we get a head room
2. But the words you have used previously are quite clear, and quite incorrect, namely about the amount of light hitting the sensor during HTP operation.mechanism behind HTP In a contrasty sunny day and at base iso 100iso there are no head room and the proximity to clippning is small.
By HTP there will be a under exposure to gain 1 stop of high lights. This is the same as let the sensor be hit by the less amount of photons as compared to 100iso and numbers of created electrons just before readout are therefore less.
and there are now 1 stop more of head room up to clipping.
The sensor collect photons nothing else and some of them will be in to electrons, there are also some gain going on.
To get the effect , lesser photons/less electrons and to get 1 stop of high light head room the signal must be lower than it is at 100iso , this can be done by shorter exposure time, change f-stop, earlier read out. + effect head room - effect more noise in lower levels.
There is no way at 100iso when the sensels are fully charged/near to clipping can get a negative amplification and therby get 1 stop head room .
Since we call 100 iso (near fully charged cell) 100iso and 200 iso 200 iso , the electron charge has been halved at 200iso and the gain has increased.
In HTP the sensor has now been hit by less light/photons = that we called 1 stop under exposure and fewer electrons has been read out which later are adjusted in the raw converter by gain and different curve
This is the same as underexpose 100 iso 1 stop= 1 stop faster shutter speed or 1 more F-stop to get 1 stop more head room and then adjust the raw file and make a own smother curve at the top.
It would be most helpful if you would rationalize the statements you have made that appear to conflict with each other. If your understanding has progressed, and you no longer believe that HTP causes a change in the number of photons hitting the sensor, then please say that. Instead, your English is really quite good and to me you are trying to write as an authority, which invites us to put your statements side by side.
Maybe it's all the foreign language manuals, schematics and engineers in person that I have to decipher..
.. because despite the imperfect english grammar and syntax, I understood perfectly well what Michael stated in that quote above.
Now it's important to many of us with tech-geek credentials to use the most correct terminology possible to describe something properly, lest we be misunderstood.. or worse. I'm willing to cut people plenty of linguistic slack as they try to describe something in a language as convoluted as english, whether it's their first language or not.
ISO 50 = YES, wish i had it available as a real ISO at times.
BTW, as an extra, i shots some crude tests with my UN-beloved 5D2 last night.
MIDTONE BANDING at iso 100 - it still has it! Real-world photos are where I first found the problem, specific test shots certainly replicate it. I need to do a few more tests just to make sure this is not a glitch of my display calibration curve but I'm pretty sure it isn't as I can accentuate the pattern with a simple unsharp function in PS.
Should i start a new topic with that when I get a chance?