I have a question about using a step up ring.  I am using a 50oc/m with 80mmCF (Bay 60).  I want to try some infrared photography so looked into a deep red filter.  The price for the Bay60 is much much more than the comparable screw in (the 67mm for ex&le).  I thought a set-up ring would be best.  Which step-up would be best?  Also, is there a size I could use and still be able to fit the lens hood on the outside of the lens?  Is this the way to go?  BTW, I have been using the cokin p system but am wary of light bleeding around the filter during the longer exposure times for infrared.  Is this a valid concern?  Thanks for the help. 
 
Jack
	
		
			
		
		
	
				
			Jack