Kodak gel filters are still being manufactured, for now, but are surprisingly expensive. On the B&H web site they go from thirty to over one hundred dollars, depending on the filter. This will date me, but I remember when they were alot cheaper than glass and could be had for three or four dollars. My advise is to invest in some B&W or Heliopan filters, multicoated if you can afford them. It just doesn't make sense to put inferior glass in front of your fine optics.