Back Focus is a mechanical adjustment for focusing a camera. It moves the image sensor in relationship to the lens to allow for different back focal lengths of lenses. This is important when fitting a zoom.
I would like to comment on your service and say that I was overly satisfied with the level of customer support. You were prompt in replying to my needs. I did have a problem with the lens that was purchased but it was fixed promptly when returned and I received it back in a timely fashion.
PRIME Investigations P/L
David from Pyrmont, No State
I would highly recommend Advance Security for any of your security needs. Every product I have purchased worked great and preformed just as described on their web site. They helped me set up over the phone and cleared up any questions I had right away. I saved a ton of money through Advance as opposed to the other so called \"big guys\" who sell the same products for much more.
Keep up the good work and I will continue to buy.
Dunrite from Mahwah, NJ
My order was packed well and I received it very promptly. I will order from Advance Security Products again in the future.
Orin from Littleton, CO
great company to deal with. wouldn't go anywhere else.service and delivery excellent.
James from Belle Vernon, PA
Item was put into service and is being monitored by a third party.
So far, there have been no complaints.