How To Backfocus A Broadcast Camera Lens

For those who are still using old school broadcast video cameras with sophisticated lenses, here's a quick tutorial on how to do a backfocus so that your shots are in focus throughout the travel of your zoom lens.

[@danalee1000]

You're absolutely right - I misspoke when I made this video. Of course, I meant when zoomed in to adjust the "focus" not the "back focus." Good catch!

[@tweekend]

Thank you. It was straight to the point.

[@fordcruz9304]

Concise but thorough. Thank you!

[@peteb2]

Helps to open the iris fully for as much light as possible through the lens and to use the Shutter on the camera to bring the image back from being over exposed. These days cameras are very sensitive so you could end up attempting to do a BF with the iris almost closed which inturn makes it real hard to see that perfect point when focusing is at it's best.

[@huthmanjagun2639]

This helps, Bravo! Great insight in a short presentation!

[@Miwu]

Thank youuu! Needed to fix this asap for a stream. Now it's fine!

[@aura19750]

Many thanks, I have found much insight in this video.Back and Front focusing are best done and achieved on a black and white monitor(if there`s any) but preferably on a white and black view finder.Camera LCDs are every so often, deceptive.However, if you have a high end color monitor you will achieve the perfect focus too.It always worked best for me when I used the legendary SONY DVCAM DSR 370P,these camera has no LCD but has a black and white electronic View Finder.

[@weeardguy]

Yep. I still miss the tube-viewfinder as I had on my GY DV500. Though there are advantages to the color LCD-viewfinder on my GY HM750, peaking is by far not what it used to be and the 'focus assist' on the camera only helps a little. Only Sony has done a better job with an excellent peaking function on their electronic viewfinders.

[@mimiimartinez3]

Thank you!

[@ChristopherWoods]

As an aside, if you have any lenses which are calibrated for Virtual Reality capture, do NOT alter the back focus once the lens and system is calibrated. By doing so the distortion characteristics through the focus and zoom range will change sufficiently to invalidate the lens' VR profile. Not a trap I've fallen into yet, but I've been strongly advised to never adjust backfocus on any of our VR studio lenses.

[@tomsid2930]

Also make sure your iris is all the way open when calibrating back focus.

[@23productionssa2]

Thanks 👍🏻!!

[@jamesandrada6463]

Shouldn't you be adjusting focus zoomed in and back focus zoomed out instead of adjusting back focus at both ends of the range?

[@papajoe7]

What lens were you using in that video is it a power zoom is it Michael 4/3 capability or do you have to get an adapter what brand and model is it what zoom range and how much is it and where can you buy it

[@austinevplab7167]

If I change my light source will I have to backfocus again with the new light?

[@jamesandrada6463]

You'll never guess why I was suddenly trying to remember how to adjust the back focus of course:

[@polymexdf69]

Thanks for sharing this I have a question what is the appropriate distance from camera to the chart so if I am shooting a weeding and subject is 20ft away then people in back ground are 50ft away how should i set this thanks

[@danalee1000]

+polymexdf69 When doing back focus with this chart, get the chart as far away as you can (at least 20', in my experience.)

[@weeardguy]

I learned it: 'If the chart can almost fully fill the field of view to just overflows the field of view when zoomed in fully, the chart is at the right distance. Also make sure to open the iris completely (get your ND-filter set as high as possible and if necessary, up the shutterspeed)

[@WeHaiti]

I just get the JVC gy 200HD can anyone tell the instruction in how to download the tape to my computer.

[@rty1955]

Only with a barrel lens much different on a box lens. And back focus is for a lens in the wide position. If you zoom in and focus, then pull back and the image goes out of focus, you have a back focus issue

[@user-xk2uf8cf2q]

you're right. and you are the second person in my life, after me, who said this... I adjust the back focus and parfocality in 3 seconds... without any zoom and tables at a wide angle )

[@benjamindbailey]

Side note: How do you remove the Fujinon TV Z lens from the body of an old broadcast camera?

[@rty1955]

If it is a box lens, you need to lossen the knob at the bottom, then tilt the lens up, then lift it straight up off the support rail

[@videocasetteTV]

Awesome , where is the knob of back focus in canon lenses

[@weeardguy]

In almost the same spot as on many Fujinon lenses. Lenses with an extender will usually have a knob that sticks out quite a bit, as the extender-bulge will limit access to the otherwise small knob.

[@videocasetteTV]

@@weeardguy thanks

[@platinumfights1128]

Good video, but when working with a Video engineer the process will be different. The engineer controls the exposure.