Originally posted by Ex Finn. His comment about the 12-24 seemed interesting and maybe helpful to OP.
I could not really see anything wrong with the lens performance from his examples. I have not used the 12-24 for IR due to filter cost, only the kit and SMCA 50 f1.7 which performs very well.
Maybe.. I'm not saying it isn't. I was just pointing that out because with a modded camera, no filter is needed and you can shoot as you normally would. Without screwing with a tripod, long exposures, the noise that comes with the method on less than perfect exposures, etc. The lens becomes far less important.
I will note that with my DA12-24 even on a normal camera, over-exposed areas seem to be more of a factor sometimes. Perhaps due to flaring. Also as many others have noted, it isn't the best in the world when it comes to PF. That, in my experience, is the case with Any UWA though. For the cost of a good 77mm IR filter, you can probably find a decent prime and use an existing IR filter with that. The Zenitar 16mm FE is a fun lens to use with IR for example. Never tried it with a non modded camera though (for IR).