After receiving a couple of PM's I thought I should explain this issue in a little more detail than I have done in the FS100 MWB thread running at the moment. Here goes:
I received a Amphibico Genesis housing for my FS100 last month and with one exception I have been completely over the moon with it. Upon initial (dry) test I found that I was not able to access the Gain controls through the pistol grips. The housing uses lanc controls to gain access to the inner workings of the camera and all controls should have been accessible. I actually thought I had received a housing with defective electronics and immediately emailed Amphibico regarding the problem. The response I got was surprising to say the least. To paraphrase the FS100 has two versions of firmware. In v1.0 full access to all the controls via lanc is possible, however in v2.0 it is not possible to access the Gain controls as this was removed by Sony in the firmware update. As I had just literally updated the firmware in anticipation of receiving the housing it is fair to say that the air around me turned a very deep shade of blue.
Not to be deterred I contacted Sony Europe about a solution and over the last few weeks we have been going backwards and forwards between Sony Europe and Sony Japan for some answers. Again I will paraphrase the answer I received. The v2.0 firmware contains lots of additional goodies and there apparently just wasn't the space in the system to keep all the old control options with the new controls. Someone, somewhere in Sony Japan decided that the Gain control would have to go and hence it was axed from the v2.0 firmware. No notification of this was given by Sony, but apparently they have a get out of jail free card here because accessing these controls via lanc is not 'officially' supported. Fairly thin ice in my book, but I'm not about to go legal with Sony over it!
Solutions? Well it is unfortunately impossible to roll back the firmware. You can however have some components within the camera replaced and get back to the v1.0 firmware via that route. The cost of the parts are not astronomical (around £30), but as yet I have no firm commitment for labour costs. Sony have refused to foot the bill as it is not a function 'officially' supported so when they removed it they removed something that 'officially' should not have been there anyway.
The turnaround quoted for the 'repair' of my camera is optimistically 6 weeks and as I am using the FS100 constantly I just have not had a window where I can spare the camera for that long. I may have one coming up over the Christmas break so in theory I should be able to get it done then, however that is also when everyone else is off work so no idea how this will affect the 6 week turnaround.
My current work around is to use the housing with auto Gain ON but limited to ISO 3200 and to then adjust the iris to get the best compromise. As the FS100 is incredibly good in low light and will give super clean images at ISO 3200 (and useable beyond ISO 6400) this has worked surprisingly well. However I've been used to shooting in full manual for years and it takes a bit of getting used to going back to auto controls. I'm just waiting for that really big screw up at a critical moment so in my opinion this is not a permanent solution.
P.S. FYI this issue should affect all housings that access the FS100 controls via lanc so it is not just a problem with the Amphibico Genesis housing. It was however a known issue when I bought the housing and I most sincerely wish that someone had let me know before I purchased it.....