Conventional wisdom is that when doing an experiment you should only have one variable - this has never stopped me from having multiple variables. In this case I was trying Ilford XP2 which is a Black and White C41 film ( think color film) developed in B and W chemicals. I used my Leica SL film camera - herein is the problem. The Leica CL takes the 1.35 v Mercury laden 625 battery which is no longer manufactured. So the workarounds include: using a Wein cell which is activated by exposure to the air, using the MR9 adapter which takes a 386 battery that you put into the adapter and then the whole thing goes into the CL, and finally there is the option of having a technician change the circuitry of the CL to take a 1.5 v battery.
I went with the Wein cell and that did not work very well - not sure why. I had exposures all over the place. The CL would occasionally get the correct exposure. The problem with the CL is the battery is installed inside the camera was you are loading the film so if mid-roll you need to change the battery you are out of luck. I also learned that certain Lens Hoods make the split image focusing not as crisp as it should be.
Now onto the XP2 in BW chemical. It does work. My negatives were either too light or too dense because of the battery issue and so I don’t think what I got is a fair estimate. I’m gonna try it again. Using XP2 in either C41 or Hc110 offers a lot of flexibility when shooting BW. You can send it off to be developed ( C41) or develop it yourself.