Manual exposure correction is arbitrarily limited to –4.99 EV?

 
 
Hi folks,
 
I do a lot of exposure bracketing for HDR purposes, using ETTR techniques. Occasionally I have individual captures that are mostly blown-out highlights, but which still have useful information in deep shadow areas. When I attempt to manually apply an exposure adjustment to such captures, I'm finding that the FRV interface simply does not allow me to enter a negative adjustment of 5 EV or more in magnitude. I've tried, but can't seem to find a way to change or circumvent this arbitrary limit. Help?
 
Thanks,
~ Justin