I just completed assembling five Packard shutters onto various front mounting panels. All are number 6 Packards, four are 3" diameter, one is 3-1/2" diameter. There are two mounting styles; a Cokin ring type which fits any lens with standard front filter threads, the other variation is a fixed dimension collar with nylon clamping screws to grip the lens barrel. The textured rubber "traction band" has a positive, non-marking grip on the lens barrel. Here are two YouTube videos showing the mounting systems: http://www.youtube.com/watch?v=9uqQmzlRMRI http://www.youtube.com/watch?v=JXc2E94_aMw&feature=youtu.be The 3" shutters shown use modified Cokin mount systems, the 3-1/2" shutter is a Collar mount system. One shutter package includes Cokin compatible set-screw collars to fit brass Petzval lenses. I prefer real rubber bulbs, not the flabby baby "snot sucker" bulbs that have poor vacuum holding capability and sluggish shutter closing action. The 1 meter (40") long tube will not "baloon" under pressure like latex tubing so bulb pressure is firm and responsive within the entire pneumatic system. A bit about Packard Shutters: Some are confused about sizes: Packard's nomenclature states that the shutter Size is the diameter of the opening, not the external dimensions of the case. The number 6 (six) is "instantaneous" (1/25 second) by inserting a synchronizing pin into a ferrule in either the front or back of the shutter. Without the pin the shutter operates in #5 "bulb" mode, staying open as long as the bulb is pressed. Here's a YouTube video showing the operation of the #6 feature: http://www.youtube.com/watch?v=2n-4Rp1lB5A&feature=youtu.be More about my Packard shutter systems here: http://re-inventedphotoequip.com/Shutters.html Reinhold http://www.Re-inventedPhotoEquip.com/
