Back Focus Instructions

[CoolDude 0]

Is there a better source for the instructions on how to back focus an auto iris/varifocal lens other than the quick instructions that come with the lens?

 

Not sure if I am doing it right or maybe I do not quite understand the idea behind backfocus. It is my uderstanding that backfocus is to provide in focus images throughout the focal range of the lens. I seem to be able to get only good focus at near or far and not through the whole range of the lens. BTW, the lens is a Computar on a Panasonic camera. Range of the lens is 6.5-39mm.

 

 

Thanks

[AVCONSULTING 0]

Back focus instructions usually come with the camera also. On most cameras it is a small screw to loosen a ring. Panasonic may have a larger focusing ring on the front of the camera depending on the model. If you are using an auto iris lens then you have to focus it at night, or put some type of filter in front of the lens to make it open fully. Otherwise you will see a good picture during the day but a fuzzy one at night. Also on vari-focal lenses they are not linear, so as you move the lens from wide angle to telephoto you have to readjust the focus. It won't track like a motorized zoom would track. If a the very widest angle or very telephoto angle it is fuzzy and you can't adjust the lens focus, then try the backfocus on the camera to bring it in focus.