<p>A couple of thoughts: are you certain the lab actually push processed your film? Second, there may be some confusion about exposure readings and settings. f/22 is actually stopped all the way down, meaning less exposure, not "wide open" as your post stated. Wide open would be f/2.8, at the other end of the settings. To attempt solving the exposure mystery, your orange filter subtracts probably 1.5 or 2.0 stops and should be factored in to the calculations. A "Sunny Sixteen" rule of exposure is to set the reciprocal of your ISO, at f/16. At f/22 an ISO 1600 full sunlit setting would be 1/3,200th second. Factor in your orange filter, and it would be between 1/1,600 and 1/800th sec. If the light was "sunny with clouds", that would require another stop of increase, from "sunny sixteen" conditions, or around 1/500th sec. @ f/22. If you exposed at 1/250th sec., f/22 you should have actually seen one stop of overexposure (greater, not less developed silver density) in your negatives pushed to ISO 1,600. So something is amiss. I suspect the lab didn't give you the push processing, and that would explain the thin negatives returned to you.</p>