calibrating lens marks?

[Shawn Nelson]

So I read here on the boards that you can't trust the distance markings on lenses and that you need to calibrate it, or re-mark it. So, how does one do this?

[Stephen Williams]

So I read here on the boards that you can't trust the distance markings on lenses and that you need to calibrate it, or re-mark it. So, how does one do this?

Hi Shawn,

If the lens & camera are collimated the marks should be good.
To re-mark a lens you need a tape measure, focus star, tape for the lens & a pen.
Set up a chart at 1',2', 5', 10', 20', 50',100', marking the focus point on the lens. Wide angle lenses will need less marks, long lenses more. With stills lenses you may not have much room so just put as many marks as easily fit.

Stephen

[Mr. Paul White]

Do accurate marks need collimation often?

Or only with bad quality glass?

[Stephen Williams]

Do accurate marks need collimation often?

Or only with bad quality glass?

Hi,

With motion picture lenses, it standard practice for a rental house to check lenses on a collimator before they leave the door. Occasionally they will need adjusting but often cleaning the mount will bring the lens back into spec. Heavy zooms that get used without the supplied support will require more work.

Stephen

[Don King]

On my partner's concern, even for a production house (so not rentals), would you advise a collimation checking out each time the cine glass is used?

[Stephen Williams]

On my partner's concern, even for a production house (so not rentals), would you advise a collimation checking out each time the cine glass is used?

Hi Don,

If you have access to the equipment it takes 30 seconds per lens so it's worth checking. With my own equipment that is never rented out I check a couple of times a year . Normally cleaning any surfaces or just tightening screws will sort out any slight errors.

If people have performed 'drop tests' then probably some adjustments will be required. Rental companies have to check equipment as production insurance companies insist on it.

Stephen

[Mr. Paul White]

Is it easy to find such equipment for sale? And easy to operate with such collimators? Is it one piece of gear? Or does it require expensive accessories? Are these systems difficult to operate and maintain?

[Stephen Williams]

Is it easy to find such equipment for sale? And easy to operate with such collimators? Is it one piece of gear? Or does it require expensive accessories? Are these systems difficult to operate and maintain?

Hi,

They are fairly expensive, so if you live near a rental house I would not bother.

If you don't change the mount (only 1 variable) then you can check the lenses yourself with a focus chart & tape measure. Only if you find a lens is wrong then that requires investigating. If all the lenses are wrong it's probably the mount that has changed!

Stephen

[Don King]

The 2/3 market is used to buy all the gear we use. On the other hand, when we're going to Africa or Asia and we are there more than half of a year, sometimes there's no even water nor doctors. Subsequently, no technicians at all.

How much fairly expensive? Will US $1,500 be enough?
Granted that link provided from you.

Or is it necessary a higher budget for other accessories or equipment?

My own experience is with 2/3" or 1/3" chips more than 20 years crossing jungles when it's not supposed to meet a rental house. I doubt if any one would rent us any piece of gear. It happens to buy some cameras only for one expedition because only a part of them will return back home. It happens.

The idea is to change mounts between PL, B4, Canon and Nikon mounts. Maybe Birger lens mounts. But given your warnings, it seems we would also need a collimator for our 35 mm recording. Can you help?

[chuck colburn]

http://www.chamblesscineequip.com/catalog/Richter%20102.htm

[Shawn Nelson]

Stephen, I don't imagine any of the rental houses will want to help me since I will be renting my Red out.

How much is a collminator? I'm now more confused, because I thought a collminator was for collminating the mount, not the lens. Or is it both?

I plan on using the PL mount and the Birger EF mount. What would happen if I don't collminate my lenses?

[Stephen Williams]

Hi Don,

Changing mounts in the field is probably not ideal, however if the mounts were correctly collimated before you went:-
Then If a mount does not line up then cleaning the surfaces will probably fix the problem, testing with a tape measure you will know if things line up.
If you are not pulling focus relying on focus marks you should be OK eye focus should always work assuming you can focus at infinity. Stopping down will hide errors too.

Clearly with your productions you have to cut corners on distant locations, been there done that!

Stephen


The 2/3 market is used to buy all the gear we use. On the other hand, when we're going to Africa or Asia and we are there more than half of a year, sometimes there's no even water nor doctors. Subsequently, no technicians at all.

How much fairly expensive? Will US $1,500 be enough?
Granted that link provided from you.

Or is it necessary a higher budget for other accessories or equipment?

My own experience is with 2/3" or 1/3" chips more than 20 years crossing jungles when it's not supposed to meet a rental house. I doubt if any one would rent us any piece of gear. It happens to buy some cameras only for one expedition because only a part of them will return back home. It happens.

The idea is to change mounts between PL, B4, Canon and Nikon mounts. Maybe Birger lens mounts. But given your warnings, it seems we would also need a collimator for our 35 mm recording. Can you help?