DIY Project? Precision Focus Reader/Marker for 5D2. Assistance Required. at DVinfo.net

John Jay · July 31st, 2010, 08:42 AM

I am running Canon EOS Utility from a 10 inch netbook as a monitor using the live view function. Using this system to pull focus is not recommended because of the lag, however as a monitor for framing it does the job well.

As you know SLR lenses do not have long throw - you are lucky if you get 90 degrees with some AF lenses! The width of a focus marker can sometimes be a deciding factor of whether you are in or out of focus.

I thought it would be nice to have a focus scale superimposed across the entire width of the screen with a pointer showing the current focus position of the lens. The basic idea is to measure the amount of movement of the focus ring and display it against the scale on screen.

I thought a neat way to do this is to take apart a wireless USB optical mouse and mount the optical sensor close to the focus ring. When the focus ring is turned the x coordinate of the mouse changes, so in effect the mouse pointer can be made to move up and down the on screen focus scale. This is the simple route, however it would be best to write a small app to do this, which I would probably do when I get to finesse the concept.

My <$10 mini USB 2.4G wireless optical mouse arrived today and this is where I have hit my first hurdle!. Before taking the mouse apart I have been doing some tests and although the mouse has switchable resolution between 800 and 1600 and is very smooth, I find that when I repeatedly move it say an inch to the left and back again, the mouse pointer does not always return to the same position, in other words there is drift. This is obviously not good and before I continue with this project I need to understand and resolve this drift problem.

Any help or suggestions are welcome!

Peer Landa · July 31st, 2010, 05:43 PM

Quote:

Originally Posted by John Jay

I am running Canon EOS Utility from a 10 inch netbook as a monitor using the live view function. Using this system to pull focus is not recommended because of the lag,

So I'm curious -- how much is the lag?

-- peer

John Jay · August 1st, 2010, 08:20 AM

Lag is about a second, maybe more

Peer Landa · August 1st, 2010, 08:23 AM

Quote:

Originally Posted by John Jay

Lag is about a second, maybe more

Yea, that's pretty much useless for follow focusing. Too bad.

-- peer

John Jay · August 1st, 2010, 08:25 AM

Further to my initial post, it appears my wireless mouse has a power save mode (to extend battery life) and so the drift is due to the micro movement which has to be detected before it kicks in to full power.

It appears most wireless mice have the power save function which is a shame.

Next purchase will be a wired optical mouse.

John Jay · August 1st, 2010, 08:39 AM

Like I said its good for framing and focus confirm, but not for pulling.

Besides that, its free!

Quote:

Originally Posted by Peer Landa

Yea, that's pretty much useless for follow focusing. Too bad.

-- peer

July 31st, 2010, 08:42 AM	#1
John Jay Major Player Join Date: Sep 2002 Location: US & THEM Posts: 827	DIY Project? Precision Focus Reader/Marker for 5D2. Assistance Required. I am running Canon EOS Utility from a 10 inch netbook as a monitor using the live view function. Using this system to pull focus is not recommended because of the lag, however as a monitor for framing it does the job well. As you know SLR lenses do not have long throw - you are lucky if you get 90 degrees with some AF lenses! The width of a focus marker can sometimes be a deciding factor of whether you are in or out of focus. I thought it would be nice to have a focus scale superimposed across the entire width of the screen with a pointer showing the current focus position of the lens. The basic idea is to measure the amount of movement of the focus ring and display it against the scale on screen. I thought a neat way to do this is to take apart a wireless USB optical mouse and mount the optical sensor close to the focus ring. When the focus ring is turned the x coordinate of the mouse changes, so in effect the mouse pointer can be made to move up and down the on screen focus scale. This is the simple route, however it would be best to write a small app to do this, which I would probably do when I get to finesse the concept. My <$10 mini USB 2.4G wireless optical mouse arrived today and this is where I have hit my first hurdle!. Before taking the mouse apart I have been doing some tests and although the mouse has switchable resolution between 800 and 1600 and is very smooth, I find that when I repeatedly move it say an inch to the left and back again, the mouse pointer does not always return to the same position, in other words there is drift. This is obviously not good and before I continue with this project I need to understand and resolve this drift problem. Any help or suggestions are welcome! __________________ John Jay Beware *PLUGGER-BYTES*

August 1st, 2010, 08:20 AM	#3
John Jay Major Player Join Date: Sep 2002 Location: US & THEM Posts: 827	Lag is about a second, maybe more __________________ John Jay Beware *PLUGGER-BYTES*

August 1st, 2010, 08:25 AM	#5
John Jay Major Player Join Date: Sep 2002 Location: US & THEM Posts: 827	Further to my initial post, it appears my wireless mouse has a power save mode (to extend battery life) and so the drift is due to the micro movement which has to be detected before it kicks in to full power. It appears most wireless mice have the power save function which is a shame. Next purchase will be a wired optical mouse. __________________ John Jay Beware *PLUGGER-BYTES*