Canon 75-300mm Lens Fine Adjustment Accessory

This lens accessory is meant for the Canon 75-300mm lens seen in the model pictures. I use it for astrophotography and never liked the focus ring and how easy it was to overshoot while trying to focus. This also prevents the focus from shifting as the worm gear will break long before you can back turn it. The print consists of 4 pieces which all print in place and need no external items for final assembly. The latch mechanism just needs the supports to be removed and then a slight amount of force is needed to get it to open the first time afterwhich it should open and close smoothly It's pretty straight forward to assemble as the larger of the two rings has a latch on it to clamp around the area below the focus ring. Be sure to put the worm gear on before gluing the knob in place and then the other ring should easily fit around the focus ring to mesh with the worm gear. If the top ring is tough to put on flip it around as the inside teeth are slightly chamfered on one side. This accessory unfortunatly prevents you from changing the focal length while mounted however you can either remove the top ring to change focal length or simply focus turn the knob till the focus is all the way out and then keep turning it this will rotate the whole fine adjust system but does also change the focal length.