Beginners... shoot f8

[Thom Steinhoff]

No DP...

Aaaagghhh!!!! What is this... for professional use?!

 

[Jeff Kilgroe]

Yeah, it's as if they expect only DP's and production companies to buy it or something...

 

[Martin Drew]

Hi,

If the resoloution is higher then you will see more difference in what is in focus and what is soft. This gives the effect of less DOF.

One of the main reason that on 1/3 chip video cameras have a large DOF. Very little resoloution (nothing is sharp) everything is equally soft!

Stephen

The main reason in this case is image magnification rather than pixel density. though it is true that it is unlikely that the glass on a 1/3" chip is going to be proportionately higher resolution that glass for 35mm.

M

 

[jbeale]

Given that the Red's sensor size is not exactly the same size as a 35mm frame, what conversion should be used in order to employ the American Cinematographer's DoF measurements?

Well, the RED sensor is not exactly the same size as a S35 frame, but it's pretty close!
Red sensor: 24.4 x 13.7 mm (16:9)
S35 frame: 24.89 x 18.66 mm (4:3)
S35 frame: 24.89 x 14.0 mm (16:9 crop)

The difference in size is only 2%, that is a crop factor of 1.02 which is pretty hard to notice. I'd say the sensor size really is S35 for just about all intents and purposes.

 

[Jeff Kilgroe]

The difference in size is only 2%, that is a crop factor of 1.02 which is pretty hard to notice. I'd say the sensor size really is S35 for just about all intents and purposes.

Yeah, but.. (and I may be wrong on this). Those are the physical sensor dimensions. When shooting 4K on RED, you're actually pulling from a 22.2x12.6mm area. To get 24.4x13.7mm, you would have to shoot full 4.5K/2540p through the RAW port.

 

[Stephen Williams]

Hi,

If you read the American Cinematographers handbook it states DOF tables are the same regardless of format! The difference between 35mm, S35mm & Red is fairly small in any case.

Stephen

 

[Mike the beginner]

I wonder if red is going to produce its own DOF chart exclusively for the red sensor. That would ensure the studying of distances relative to the lenses and aperture used is accurate.

A little pocket Red one DOF chart made in plastic and fully waterproof is for me an absolute must.

It is frightening for me to know that when using the 300mm prime on a sturdy tripod the DOF is going to be very narrow indeed. This is where the absolute correct chart relative to the COC is going to be needed. The Red DOF pocket chart will be with me all the time.

This is all going to be new to me, so practicing with another camera would have been useful. Since i have no other camera i have been practicing guessing the distances from imaginery camera point to subject. In the short space of six months i am amazed how good you can become at guessing the distance in general.

PS i am not referring to the usefulness of distance guessing with the likes of the 300mm lens (would that be brilliant) just more the red zoom.

So will red produce their own pocket chart or not. If not will a third party do so?

PS Stephen i read up on this a while ago the COC is different with different sized sensors. The precieved DOF is different. There are practice charts that show you the difference.

Mike the beginner

 

[ChristopherKenworthy]

I noticed that Jim mentioned a laser range finder. I've wondered for a long time if one of these was being built into the Red One, as all the mock-up pictures show a big red glow coming out of the camera. And focus will be an issue, so maybe a readout from a laser would be useful for a focus puller, saving time walking up to the subject at every mark. Having never been a focus puller, I don't know if this would even be a useful device, but who knows.

 

[Finner]

I noticed that Jim mentioned a laser range finder. I've wondered for a long time if one of these was being built into the Red One, as all the mock-up pictures show a big red glow coming out of the camera. And focus will be an issue, so maybe a readout from a laser would be useful for a focus puller, saving time walking up to the subject at every mark. Having never been a focus puller, I don't know if this would even be a useful device, but who knows.

Nice eye Christopher I had not noticed this. I worked as a focus puller for quite a while and panavision has a version of this they call the pana-tape that works very well. Arri also has a version of this and I use to own a surveyers version of this that worked well and was handy. This would be a good option but I do not know if there is a location on the camera itself that it could be placed that the matte box would not be in the way of. The pana-tape mounts on the top over the matte box.

 

[M Olsen]

Hi,

Film is never flat when running, fearly flat maybe!

A sharper lens will show less DOF, not more!

Stephen

As Stephen correctly points out there is a variance in film when running. As such it is susceptible to shallow Depth of Focus which, although related to and influenced by, is different to Depth of Field.
A perfectly flat sensor and an exact lens flange depth setting should remove the variance and maintain a "sharper" feel at all apertures and lens focus settings. But hey, better minds than mine can clarify this. I just shoot the stuff.

 

[M Olsen]

Nice eye Christopher I had not noticed this. I worked as a focus puller for quite a while and panavision has a version of this they call the pana-tape that works very well. Arri also has a version of this and I use to own a surveyers version of this that worked well and was handy. This would be a good option but I do not know if there is a location on the camera itself that it could be placed that the matte box would not be in the way of. The pana-tape mounts on the top over the matte box.

Most experienced 1st AC's I have worked with on drama in recent years use the Leica laser rangefinder and "sight" it from alongside the focal plane. It is useful when on a crane etc or for last minute checks, but anyone worth their salt always does the tape thing first to establish distance references.
Its a changing game though and each to their own as long as the job gets done.

 

[Sean]

I wonder if red is going to produce its own DOF chart exclusively for the red sensor. That would ensure the studying of distances relative to the lenses and aperture used is accurate.

That would be super useful...and will undoubtedly come in Barry Green's Red Manual.

 

[Brook Willard]

I noticed that Jim mentioned a laser range finder. I've wondered for a long time if one of these was being built into the Red One, as all the mock-up pictures show a big red glow coming out of the camera. And focus will be an issue, so maybe a readout from a laser would be useful for a focus puller, saving time walking up to the subject at every mark. Having never been a focus puller, I don't know if this would even be a useful device, but who knows.

The glow you saw on the front of the camera in the renders was for show only. The PL-mount and RED logo below it do not glow.

As was mentioned earlier in the thread, many ACs carry a Leica Disto or similar laser range finder... they're wonderful. When I work as an AC, I generally request a CineTape or PanaTape measure. While there are obvious limitations with such systems, it's fantastic when you know what you're looking at. Is the camera peeking through foreground? The number's probably wrong. Is the camera aiming at one person in an empty room? Pff, shoot at a 1.3, I got this.

As for RED DOF, there is no need for a RED-specific DOF chart. DOF does not change, regardless of format. For example:

You have a 50mm lens on your camera. Your subject is at 10'. You're shooting at F:2.0.

Your near DOF is 9'5" and your far DOF is 10' 7.75". This figure will not change on any format - be it 1/3", 2/3", S16mm, 35mm, S35mm or RED. What will change is your field of view [FOV].

Where DOF appears to change between formats is when FOVs are matched. For example, a 50mm on S35mm will have a very similar FOV to a 25mm on S16mm. Because we are now using different focal lengths, the DOFs will be different [even though the FOV is now "the same"].

Obviously there is a difference between film and a bayer-pattern sensor's DOF. So now does the RED need a custom DOF chart? Nope. Here's why:

1: The perceived DOF will change based on the lenses. As mentioned earlier in this thread, Cookes and Arri/Zeiss lenses transmit different wavelengths in different quantities. As a result, different lenses will appear sharper or softer depending on their wavelength transmission and aberration characteristics. Two lenses of the exact same focal length can have different DOFs.

2: Determining what is in "acceptable focus" and what isn't will always come down to the operator. In the aforementioned example, I could set my focus to 10'6" and technically be "sharp" according to my DOF chart. But am I sharp? No. I'm barely within what is deemed acceptably sharp by some formula created eons ago. The difference in what is acceptable and what isn't changes from person to person, show to show and shot to shot.

Long story short? Get your 35mm DOF and suppose that you have slightly less DOF than the chart states.

The real answer? Don't go soft.

 

[Stephen Williams]

PS Stephen i read up on this a while ago the COC is different with different sized sensors. The precieved DOF is different. There are practice charts that show you the difference.

Mike the beginner

Hi Mike,

I think you will find it's the resoloution of the film/sensor combination rather than the actual size of the sensor.

By using Zeiss Digi Primes on a 2/3 inch sensor wide open, you could well end up with less DOF than Nikon stills lens on a Red. The Zeiss is very sharp at T1.5, the same is not true for most Nikon lenses.

I am of course unable to test this theory at the present time. I have shot on a Viper with prime lenses wide open. I found that I got far less DOF than the DOF calculator on Panavisions web site indicated.

Stephen

 

[Joel Kaye]

That would be super useful...and will undoubtedly come in Barry Green's Red Manual.

Barry's been unusually quiet about RED - at least around here. Is he not a RED head? Staying P2 perhaps?

 

[Steve Gibby]

Jarred answered that on a thread last month. Barry is holding down the DVX User fort...

 

[Charles Papert]

I would say that you guys shouldn't get too nutty about DOF charts. It would be good to browse them to get a sense for how aperture and focal length conspire individually and in combination to affect DOF, but in regular practice you won't often need to refer to them. Usually they are used to calculate a split, which is when you are trying to hold focus on two people at different distances to the camera (a classic example is a side angle on a driver and passenger in a car from a side mount aka hostess tray; if you want both to be in focus, consult the chart to see what stop you should be shooting at). One very portable device that many assistants use is a Kelly wheel(http://www.filmtools.com/kewhakakeca.html); a more high-tech version is a set of handy Palm apps that have many great features including a field-of-view visualizer: p-cam and p-cine (http://www.davideubank.com/).

Regarding the circle of confusion or comparison to 35mm, my experience with the Genesis has led me to the conclusion that the DOF characteristic of 35mm sized digital sensors is noticeably shallower than 35mm film. One top-notch AC that I work with feels that it is somewhere inbetween spherical and anamorphic 35mm, which is very shallow. Anyone who is currently planning their first RED feature would be well advised to plan on hiring an experienced AC who has pulled 35mm--you'd hate to find out down the road that the fruits of your labor are soft.

And for those training themselves now, spending some time on set observing a skilled AC is worth its weight in gold. There's a tremendous amount of voodoo and a myriad of techniques involved, and no two assistants do it the same way. Tools like the Panatape and Cinetape and laser systems like the Long Ranger and Sniper are very useful but generally not while the subject is moving, which is usually the tough part. I was working on "Ugly Betty" last week and we shot two guys sprinting towards camera at a variety of focal lengths up to 275mm. The AC did a fantastic job with the challenge, but FYI he has been pulling for 15 years or so. He took reference points via eye focusing through the viewfinder with the 2nd AC holding a slate at specific points along the route. After each take I was able to give him notes on the sections of the shot that did buzz, so he could adjust those on subsequent takes. I look forward to seeing the RED viewfinder in action and hope that it improves on the status quo of HD viewfinders (and also the "magic focus" feature, whatever it may prove to be).