How do you use the measuring tape to measure your focal plane.

GABRIEL GARCIA ROSA

GABRIEL GARCIA ROSA

New member
this maybe a dumb question to ask since all of you are all pro but for someone still very new to the game i would like to know how you measure focus using a tape measure?

i apologize for such a noob of a question.
 
Well, you run one end of the tape to the place where you want focus while the other end is at the sensor plane. Essentially where the sensor is located on the camera.

At times there is a sign on the camera saying where the focal measuring plane is. In some other cameras you just learn where the sensor plane is located, such as on the RED.

But in general terms, find out where the sensor plane is, hold one end of the measuring tape there, and run the tape to where you want to set focus. It also helps to make an educated guess as to what the distance is by eye before running your measuring tape; that way, you begin to train your eye and get it used to determining distances. After a while you may start guessing correctly down to the inch!
 
i'm pulling focus to an actor who moves from starting position to another position, now how would i measure that using a tape measure and how will it correspond to the lens? how would i mark that on the follow focus?
 
Be aware though that this technique is strictly limited to cameras that have properly-collimated lenses and mounts. There is no point in trying to measure distance on an SLR lens, for example... the lenses aren't marked accurately enough to make the focus markings anything more useful than general guidelines.

Measuring focus is only trustable when you're using properly-marked cinema lenses, with proper witness marks, which have been properly collimated on an optical bench, on a camera whose mount has been properly shimmed to the right depth.
 
GABRIEL GARCIA ROSA said:
i'm pulling focus to an actor who moves from starting position to another position, now how would i measure that using a tape measure and how will it correspond to the lens? how would i mark that on the follow focus?
Click to expand...

If you're shooting on a cine camera like the Red or the AF100 and you're using properly-collimated lenses, then it's no big deal -- just have them stand on their first position, measure out the distance, then focus to that mark, check that the focus is perfect, and then mark that position on your white disc on your follow focus. Then have them move to the second position and repeat the process.

But, again -- don't bother with the tape measure unless you're using the right equipment with it. You can do the type of thing you're talking about by taking focus marks by eye and marking the spots on your follow focus (assuming, of course, that your follow focus and your lens are both completely repeatable).

What kind of camera and what kind of lens?
 
It coresponds to the numbers on the lens, ft. or meters. I dont measure much, I usually have the actor go to point A, Then mark the disk and mark the floor with a piece of tape, or something that will be a landmark. Then I have him go to point B, Then make my second mark on the focus disk, then put another piece of tape on the floor. And so on. I use different color markers on the marking disk. Point A, is always green, Point B=red, C=BLUE. Some people measure everything, I guess it's what works for the way you shoot, I like to go fast, and try to spend little down time if I can.
 
thank you so very much for being kind. i asked this same question on reduser.net and suddenly i was attacked becuz my name was all in caps and i typed all in lower case. which never really answer any of my question at all becuz they were so focus on Netiquette.

that camera that i am using is a 7D (HDSLR) and the lenes are from canon . i'm using a 50mm, 25mm, and a 18mm.
 
GABRIEL GARCIA ROSA said:
thank you so very much for being kind. i asked this same question on reduser.net and suddenly i was attacked becuz my name was all in caps and i typed all in lower case. which never really answer any of my question at all becuz they were so focus on Netiquette.

that camera that i am using is a 7D (HDSLR) and the lenes are from canon . i'm using a 50mm, 25mm, and a 18mm.
Click to expand...

I'd use the 'manual focus, mark', for the the actor's beginning and ending locations, and then change focus during the movement... to paraphrase a famous movie line... the rule lines on the typical 35mm still lens are more like guidelines...

A more complex movement may require more marks.
 
There's plenty of cool redusers, and there's also plenty of arrogant jerks as well. Although this is the case on any forum and with any subject. People need to remember, they were once newbs too. So It's always good to give back the knowledge that was shared with you. It's like borrowing a book, read it then pass it on. Share the wealth.

Reduser requires people use their real names, This way it makes people think about what they write as they cant hide behind a fake persona.
 
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