Editing 35 mm movie film (section)

===BH perforations=== 
Film perforations were originally round holes cut into the side of the film, but as these perforations were subject to wear and deformation, the shape was changed to what is now called the [[Böwe Bell & Howell|Bell & Howell]] (BH) perforation, which has straight top and bottom edges and outward curving sides. The BH perforation's dimensions are {{convert|0.110|in|mm}} from the middle of the side curve to opposite top corner by {{convert|0.073|in|mm}} in height.<ref name="case">{{cite book |last= Case |first=Dominic |title=Motion Picture Film Processing |location=Boston |publisher=Focal Press |year=1985 |isbn = 9780240512433}}</ref> The BH1866 perforation, or BH perforation with a [[Film perforations#Pitch|pitch]] of {{convert |0.1866|in|mm}}, is the modern standard for negative and internegative films.<ref name="Kodak motion film specs">{{cite web|url=http://motion.kodak.com/motion/uploadedFiles/US_plugins_acrobat_en_motion_newsletters_filmEss_11_Film_Specs.pdf#page=3 |archive-url=https://web.archive.org/web/20110107142747/http://motion.kodak.com/motion/uploadedFiles/US_plugins_acrobat_en_motion_newsletters_filmEss_11_Film_Specs.pdf |archive-date=2011-01-07 |url-status=live |title=Perforation Sizes and Shapes |publisher=[[Kodak]] |work=Motion Newsletters |date=October 30, 2007 |access-date=March 14, 2012 |page=95}}</ref>