Shooting 24p Projected Film

[lumiere]

Hey David,

We're using a RED One in a telecine configuration shooting film projected on a small white screen (playing at 24 fps).

We're shooting the white screen in 4K @ 23.98. I made the assumption that the shutter speed should be 1/48 sec. but a nasty flickering is noticeable.

Almost not noticeable when shooting a 1/60 sec. which is counter intuitive for me but seems to work.

Any feedback?

Thanks!

Frederic Lumiere

 

[Mark L. Pederson]

Hey David,

We're using a RED One in a telecine configuration shooting film projected on a small white screen (playing at 24 fps).

We're shooting the white screen in 4K @ 23.98. I made the assumption that the shutter speed should be 1/48 sec. but a nasty flickering is noticeable.

Almost not noticeable when shooting a 1/60 sec. which is counter intuitive for me but seems to work.

Any feedback?

Thanks!

Frederic Lumiere

Blast from the past! Great to see you posting Frederic!

Not sure re: the shutter - only would assume it has something to do with the fact it is an electronic shutter and is not rotating.

 

[lumiere]

Is this Mark "The Sexiest Producer on The East Coast" or Aldey "The Smartest Producer on The East Coast"?

F

P.S. I think you are correct on the electronic shutter

 

[Mark L. Pederson]

Is this Mark "The Sexiest Producer on The East Coast" or Aldey "The Smartest Producer on The East Coast"?

F

P.S. I think you are correct on the electronic shutter

We should get together soon.

word on the street is that Nacho from Assimilate is throwing the greatest party ever at IBC 2008 ... best DJs in the world, etc. - be a shame if you couldn't make that!!

 

[lumiere]

I'll give Neve Campbell a call and see if she can make it.

Unfortunately, I don't think I can make it - I'll either be in Russia, London or Amsterdam shooting History's biggest series ever...

Wait... did I write Amsterdam? hmmm... maybe I need to be creative with our scheduling.

F

 

[Dan Hudgins]

Shutter angle...Stop motion...

Shutter angle...Stop motion...

Hey David,

We're using a RED One in a telecine configuration shooting film projected on a small white screen (playing at 24 fps).

We're shooting the white screen in 4K @ 23.98. I made the assumption that the shutter speed should be 1/48 sec. but a nasty flickering is noticeable.

Almost not noticeable when shooting a 1/60 sec. which is counter intuitive for me but seems to work.

Any feedback?

Thanks!

Frederic Lumiere

You don't say if it is a 16mm or 35mm projector or if the projector has a 2 blade or 3 blade shutter, or is a TV film chain type projector.

35mm Projectors can have blades that are not both the same size, and the image gets projected two or three times, you can figure that out by inching the projector with a reduced light source.

To transfer film you will do MUCH better to do it single frame, my program DANCINES.EXE (tm) is "freeish" and computerizes scanning using a movie projector or optical printer. It can skip over parts you don't want to scan from a cue file.

You can butt the RED ONE (tm) lens up to the projector lens, if you are scanning 35mm and your projector has a 4" lens you would set the RED ONE (tm) lens to about 100mm also to get the image to fit, and stop down to about f/11.

You would need to replace the projector lamp with a LED lamp or low wattage, and open the damper. Then wire a motor to advance the projector one frame at a time.

You don't need my program if you put a slow motor on the projector and have a micro switch fire the RED ONE (tm) single frame each time the projector advances.

If you can get the RED ONE (tm) to single frame faster than 24fps, you could put an HALL EFFECT or optical switch on the projector and trigger the RED ONE (tm) to stay in sync with the projector, you might take the shutter out of the projector since it would not be needed with the camera in sync. If there is a gen-lock input on the RED ONE (tm) that might also be used to sync to the projector, but single frame will give better results probably.

When you point the camera into the projector lens you need to flip the frames from the RED ONE (tm) later.

You can also put a field lens between the projector and camera to avoid dark corners and get crystal clear arial image that will let you stop down the camera lens to get better 4K detail. The field lens does not need to be big, you can put Achromatic diopter lens on both the projector and camera lens to focus down to an arial image (inside the large field lens [not fresnel please!]) about 6" wide or smaller.

Be sure you cut down the light on the projector since the image in the camera will be much brighter with arial image relay optics like this.

Most projectors do not have a sync motor so the frame rate can vary from 24fps, to measure the projector frame rate put a photo cell in front of the projector with film in it and running with the light on, then hook the photo cell to an o'scope and set H sweep to line, if the pattern stands still without drift then the motor is sync, if the pattern moves left to right then the projector is not in sync with the 60Hz line. If your o'scope is digital you can measure the time the light coming out of the projector is on to tell the projector frame rate cycle, which may change if you put your hand on the supply or take up reel (when the motor is non-sync).

The crystal in the camera will be out 1 frame in about 4 minutes or less, so if you take the shutter out of the projector and it has a sync motor and the camera runs at 24fps, you might avoid the pull down for a minute or so and get flicker free recording (it will take a few tries to get the camera and projector in sync, you need to flick the power to the projector on and off quickly to get the sync motor to pop the pull down into the RED ONE (tm) dark shutter time. If the projector is not sync or the RED ONE (tm) is not running 24fps then the pull down will come and go faster than every four minutes.

BTW, remember the NTSC frame rate is 1000/1001*24=23.97602398+fps so does not divide into line 60Hz, the old vidicon had enough stick to reduce the flicker drift for the frame rates not being in a simple ratio (no sure if some drove the sync motor from the VHz using an inverter also).

If you want to transfer film I would do it at 24fps whole frames, single frame at a time, and adjust the sound later to match the reduced 23.976+ frame rate (you resample the WAV to make it a little longer).

Another option would be to servo lock the projector to the VHz of the RED ONE (tm), then you could get 1:1 frame coherence at the camera's frame rate even if the camera is not right on speed (its crystal is probably a little off anyway). You can probably pick off the RED ONE (tm) shuter phase by monitoring the camera's current draw, there may be a small ripple at the camera's frame rate that you can filter and amplify with AC coupling, that can then drive the sync motor on the projector through an DC-to-AC inverter (e.g. 1000W amp with up to 180VAC output) with a phase adjust (a graphic equalizer can be used to adjust the about 60Hz phase of the drive signal with the low end sliders). For a sync motor to work on a projector it must use timing belts or chains rather than V belts and such.

 

[lumiere]

DANCAD3D (tm):

Wow! First I have to say that writing (tm) everytime you write RED ONE is the dorkiest thing I've seen in a while.

But I have to admit, you blew my mind with your post.

Incredibly informational.

Frederic
A dork in disguise

 

[Dan Hudgins]

Anyway...

Anyway...

DANCAD3D:

Wow! First I have to say that writing (tm) everytime you write RED ONE is the dorkiest thing I've seen in a while.

But I have to admit, you blew my mind with your post.

Incredibly informational.

Frederic
A dork in disguise

If you would like to get rid of you flicker I am happy to give you some ideas, you can contact me directly, if not...

 

[Dan Hudgins]

Cannot sign up for your spam filter.

Cannot sign up for your spam filter.

If you would like to get rid of you flicker I am happy to give you some ideas, you can contact me directly, if not...

Thanks for the direct email, my reply was held up by your spam filter.

I cannot sign up for your spam service, so I sent you a copy of my reply through the REDUSER.net PM service to answer your question about Monday.

If you would like to ask more questions please get a open gmail or yahoo email so you can get replies from me directly about your telecine project.

 

[lumiere]

Ah, spammarrest just wanted you to prove you were a real person. It didn't require you to signup.

I authorized your email anyway and responded.

Thanks!

Your post is fascinating.

 

[Dan Hudgins]

DSLR problems with mechanical shutter issues

DSLR problems with mechanical shutter issues

Ah, spammarrest just wanted you to prove you were a real person. It didn't require you to signup.

I authorized your email anyway and responded.

Thanks!

Your post is fascinating.

Thanks, I sent a reply, this might be of interest to people using DSLR,

...

Anyway, the mechanical shutter in a DSLR will break after 100,000 to 250,000 exposures so there is a high cost to using 10 to 20 DSLR to scan a feature if you make the required 9 exposures per frame, the RED ONE (tm) does not have the mechanical shutter so should run without issues.

There was talk about using the USB to single frame the RED ONE (tm), it would have been better to just have a sub-mini phone jack like an DSLR. If they have this working you can maybe modify a mouse to connect to my or someother scanner software.

Talk to the people on REDUSER.net into motion control, i.e. stop motion.

If the stop motion is not working yet, you might be able to set the frame rate to a slower value and sync the projector to that lower frame rate.

Using an industral MONOCHROME camera without mechanical shutter should give better results than a DSLR if it has a wide dynamic range. But since the DSLR has OLPF and wide dynamic range and pixel defect maping it can be better for short tests to get started.

The mechanical shutter in DSLR can flake off dust onto the sensor, so after you scan 400 feet you may start seeing spots on the sensor from dust.

I say to scan 9 images per frame since you can set the autobracket feature in a DSLR to shoot three shots high-mid-low to get more range off the film, it also helps overcome the limits of the digital steps in the tonal range, then the three red, three green, and three blue exposures are FUSED together to make one 48bpp frame file. This looks better than a single exposure using the Bayer filter. For stop motion with the RED ONE (tm) I would also recomend using a filter wheel in front of the camera and making 9 exposures to get better results.

Hope this helps a little...