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Your Approach to Metering for Nighttime Exterior Filming (500T)


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#1 Karl Lee

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Posted 02 November 2014 - 08:09 PM

So far, a vast majority of my S16 experimental filming has been daytime exterior, but I'd like to pick up a roll of 500T and try some nighttime exteriors.  When filming outside in daylight and shooting objects far off in the distance, I'll typically take an incident meter reading at my location and use it as a starting point and rough estimate to determine my exposure for the shot.  Metering for nighttime shots, however, seems like it would require a completely different approach.  

 

If, for example, I was filming a nighttime skyline, a street illuminated by a few streetlights and cars driving by, or another object or scene far off in the distance, an incident reading from the camera location would likely be of little to no help, especially if the camera is situated in a spot that is much darker or brighter than what's being filmed.  That said, is determining proper exposure for nighttime exteriors (and specifically distant objects or scenes) more about working form experience and intuition as opposed to relying on a meter reading?  And, when shooting nighttime exteriors with 500T specifically, do some just set aperture at something around T2.8 and take a "set it and forget it" approach, or is this generally not a safe assumption?

 

I suppose spot metering is also an option, but I'm not terribly experienced with proper interpretation of spot readings, so I'll probably steer clear of that at this point.

 

Thanks for any help! 

 

 


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#2 Bill DiPietra

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Posted 02 November 2014 - 08:23 PM

I'm about to start shooting a night shoot with 7219.  I'm also pushing it 2 stops, but I haven't shot any night exteriors with only ambient light just yet.  But whenever I've done exteriors, I've very often used reflected light readings, especially if I'm shooting a horizon or something.  This all depends on the shot, of course.

 

Also, I live in New York City, so there is plenty of light even at night.  I'm not sure how dark the nights are where you live.  But I once stepped outside at night and checked a reflected light reading with 7219 rated at 500ASA.  There were plenty of street-lamps and store signs so it came up around a T2.  I would still re-meter for every shot if it were me.

 

Also, if you decide to rate the film at 2K, bear in mind that pushing 2 stops only really gets you 1 & 2/3 stops as was explained to me very recently by a senior technician from a highly reputable lab.


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#3 Satsuki Murashige

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Posted 02 November 2014 - 11:10 PM

A spot meter is the correct tool for the job. Or failing that, at least a reflected meter of some kind as opposed to an incident meter. Worst case, you could use the reflected meter in a film SLR or a DSLR. It's easy to use, just remember that the reading a spot meter gives you assumes that the subject you are metering should be exposed for middle grey. So if you're metering bright highlights that should be 4 stops over middle grey, or shadow detail that should be 2 stops under, then you need to compensate with the aperture on the lens.


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#4 Kenny N Suleimanagich

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Posted 03 November 2014 - 12:39 AM

To back up Bill’s words, I remember John Pytlak writing about the previous 7218 not gaining much sensitivity at a two-stop push while gaining a lot of grain. 7219 is very very close to ’18 with slightly more latitude, and you might find yourself not needing the push. 

 

500T with Super Speeds can keep you pretty safe in the dark.


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#5 Mark Kenfield

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Posted 03 November 2014 - 06:52 AM

It's been a while since I last shot S16mm, but I quite liked setting my DSLR for 500 ISO, 1/50 and f/1.4 and seeing what it got me. It's a nice way to confirm the spot readings I was getting from my meter.


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#6 Bill DiPietra

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Posted 03 November 2014 - 10:20 AM

To back up Bill’s words, I remember John Pytlak writing about the previous 7218 not gaining much sensitivity at a two-stop push while gaining a lot of grain. 7219 is very very close to ’18 with slightly more latitude, and you might find yourself not needing the push. 

 

500T with Super Speeds can keep you pretty safe in the dark.

 

Yes indeed...7219 is very grainy with a 2-stop push.  So I wouldn't use it simply for extra exposure.  It should only be done to achieve a desired look.


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#7 John E Clark

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Posted 03 November 2014 - 02:06 PM

While not 'film'... nor 'moving picture', I would meter this essentially the same... shot for the 'white' billboard to be 'white'... and accepted the dark areas where they fell from there...

 

4161784693_dbe06e0690_o.jpg

 

In this case, I just was sort of taking a 'casual' night exterior, and could only really 'meter' for 'can I get anything?'... BMPCC f/2.8 ISO 1600 180 deg. 24 fps.

 

14947856804_b5d417e1cf_o.jpg

 

Since the shot had a low 'somewhat white brick wall' I put that as 'high' as I could. Since this is a 'log' representation, I probably could adjust to get a better 'white wall' look.

 

But basically, it was metered with a spot meter looking at specific elements and placing them, as best as possible, given the limitations of my medium.


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#8 Karl Lee

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Posted 09 November 2014 - 07:48 PM

Thanks to everyone for the tips.  Unfortunately I don't have a DSLR, so using one for reference isn't an option at the moment.  I'll probably end up getting some 500T, using my spot meter to make some semi-educated metering guesses, and just giving it a try.  I suppose it wouldn't hurt to learn a little more about the Zone System before I start :)

 

Using the top image that John posted (with the Chase billboard) as an example, how would one go about spot metering for that particular scene?  Conventional wisdom might be to take a spot reading of the billboard, but not only is it white, but it's also heavily illuminated compared to everything else in the scene.  Instead, I suppose being able to properly interpret a spot reading from the illuminated billboard, in addition to spot readings from other subjects in the scene, is ultimately the key in being able to determine an optimal exposure for this any given scene.


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#9 David Mullen ASC

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Posted 09 November 2014 - 10:01 PM

Depends on the look you intend, but it's a bit like panning from a bright window with a view to a darker area of the room, odds are high that you will be doing a stop pull after deciding how many stops over is OK for the window and how many stops under is OK for the room.

The other thing to keep in mind is that film negative loves exposure so err on the side of more exposure.
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#10 Guy Holt

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Posted 10 November 2014 - 11:55 AM

Thanks to everyone for the tips.  Unfortunately I don't have a DSLR, so using one for reference isn't an option at the moment.  I'll probably end up getting some 500T, using my spot meter to make some semi-educated metering guesses, and just giving it a try.  I suppose it wouldn't hurt to learn a little more about the Zone System before I start :)

 

Using the top image that John posted (with the Chase billboard) as an example, how would one go about spot metering for that particular scene?  Conventional wisdom might be to take a spot reading of the billboard, but not only is it white, but it's also heavily illuminated compared to everything else in the scene.  Instead, I suppose being able to properly interpret a spot reading from the illuminated billboard, in addition to spot readings from other subjects in the scene, is ultimately the key in being able to determine an optimal exposure for this any given scene.

 

IMO the the Zone System is the way to approach this since it was a way to solve the problem of fitting high contrast subjects into visual mediums with limited contrast.    But you will have to modify it for the digital age because, as developed by Ansel Adams, it was originally a means of correlating exposure of film in a camera with development and printing procedures. Generally there were three steps to the Zone System. One was to form a mental picture of how you wanted the final image to look in terms of brightness and contrast. The second step was placement – figuring out which tones would fall into zones of the medium’s “characteristic curve” by adjusting exposure in the camera, the development of the film, and the final printing.  Obviously, similar steps can be taken with digital cameras and digital post processing. For digital, the first two steps of visualizing the final print and placement of tones into zones can still be relevant.  For the third step, digital processing techniques take over. Where photographic printing has become uncommon, the visualization is just for how the image will look on a monitor.

 

c9db1865-2b58-4537-be64-2f430a49a9b8.jpg

 

The zones and what falls into each are detailed in the table above.  These reference points and how they relate to each other (a zone is one stop more or less reflective than the zone next to it) will enable you to expose film or digital video when the light falling on a seen is not uniform and there is not a mid gray tone (commonly called the “key” tone) in the scene to expose for as is the case here. To understand how to use the Zone System it is important to understand the significance of the key tone which falls into Zone V.

 

The key tone, or mid gray because it appears in the middle of a photographic gray scale, is the common reference point used by light meters, lab processors, and transfer colorists.  A lab processor knows what density his processed emulsion should be to render mid gray and so he is able to adjust his processing accordingly. A transfer colorist knows what gain will reproduce the luminance of mid gray so he is able to set his gain. Simply put it is the reference point to which we peg all other values on the characteristic curve of the film or digital format we are using. Meters are likewise calibrated for mid gray. For example there are basically two types of meters: incident and spot.  Incident meters read the light falling on your subject. Spot meters read the light reflecting back from your subject.  An incident reading gives you an exposure that after normal processing would  render an 18% gray card as 18% gray (a specific density of the film) had you held it in front of the camera in the same light.  Incident meters enable you to peg the key tone (18% gray) in this fashion even though there may not be a mid-tone in your scene.

 

A spot meter is then typically used to take reflective readings to see how other objects will expose relative to the key tone that was pegged with the incident meter.  The thing to remember about spot meters is that they want to expose everything as mid gray.  For instance, if you expose a black piece of paper with the reading of a spot meter it will appear as mid gray after normal processing (not pushed or pulled) – likewise for a white piece of paper. But, if you place an incident meter down on the black piece of paper and expose for the incident reading the black paper will be black, and the white paper will be white, after normal processing because you exposed for the key tone by using the incident reading and thereby pegged the other values (white and black) relative to it. If you don’t have an incident meter, but want to peg the key tone under your subject's key light, you can use the Zone System. Since average Caucasian flesh tone falls into Zone VI or one stop brighter or more reflective than mid-gray, if you take a spot meter reading of the palm of your hand under the key light and open up one full stop you will have a close approximation of mid gray.

 

Metering_characteristic_curve.jpg

 

(The “Characteristic Curve” of a high contrast B&W Reversal emulsion. The object of exposure is to place the contrast range of the scene on the straight line portion of the curve so that the different luminances of objects in the scene are reproduced accurately on the film. Mid gray being the common reference point.)

 

 

Since the 8 stop range (zones II through IX) of the Zone System fits comfortably into the exposure range of most digital cameras and film stocks available today, it offers you a means of not only pegging key tonal values but also compressing the contrast range of your scene so that it fits into the exposure range of the visual medium you are using – steps 1 and 2 of the Zone System as initially described above.  How you do this is by using the reading from the spot meter to be sure that the object you are metering will fall into its’ corresponding zone. Let’s take for example the image below.

 

4161784693_dbe06e0690_o.jpg

 

If the information on the billboard was important, but you wanted it to be the hottest object in the shot, you would place the light background of it in Zone IX (four stops over mid gray) so that it would be bright but still hold texture. If you then take a reading of the shadowed side of the porta-potty where you also want to hold detail and it is ten stops below the spot reading of the sign, you know it is likely outside the exposure range of the film stock you are using and it will block up to a black without detail because it is below Zone II.

 

Since in this situation the contrast range of the scene is beyond the exposure range of the film you have two choices. 1) You can open up and expose for the shadows (over exposing the key tone and blowing out your highlights more in the process) and print down to make mid gray mid gray again. In the end you have the detail in the shadows you want, but in the process you have lost detail in the highlights.  Why?  Because the contrast range of the scene was beyond the exposure range of the film, and you exposed for shadow detail, you burned out the highlights (no detail) so it is not there when you print down to mid gray.  You can't bring it back. Is that bad? Not necessarily. It's just another "look" but not the look you are after since you want to hold detail in the billboard.

 

Metering_Scene_Contrast.jpg

(The contrast range of this exterior exceeds the exposure range (flat line portion of the “Characteristic Curve”) so shadow details, in his hair and the black felt under the MacBeth Chip Chart, that fall on the bottom of the ”toe” of the curve “block up” (max density) and detail in that area of the frame is lost. Likewise, highlights like the specular sun on the windshield and the white towel, that fall on the upper end of the “shoulder” of the curve “burn out” (min density) ) and detail in that area of the frame is lost. The object of lighting is to compress the contrast range of the scene so that it fits on the straight line portion of the curve so that the different luminances of objects in the scene are reproduced accurately on the film.)

 

Or, 2) you can throw some light into the shadowed side of the porta-potty to bring it’s reflective value up into Zone II and onto the exposure range of the film (onto the straight portion of its’ characteristic curve) without changing the exposure of the key tone value (mid gray) or blowing out the billboard.  In this fashion the Zone System enables you fit the contrast range of your scene into the exposure range of the film emulsion you are using. This is old school film exposure theory, but it is a good conceptual frame work for exposing digital video, especially now that you can record "raw" and apply "looks" to the raw data.

 

Guy Holt, Gaffer, ScreenLight & Grip, Lighting Rentals & Sales in Boston


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#11 Stuart Brereton

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Posted 10 November 2014 - 12:02 PM

Using the top image that John posted (with the Chase billboard) as an example, how would one go about spot metering for that particular scene? 

I would meter the billboard, and then decide how I want it to look. If I want it to be white, I'll open up 3 stops from the meter reading. If I want it to really 'pop', as bright objects do at night, i might give it another stop of exposure.

Film has a lot of over exposure latitude, so you might want to overexpose the billboard by a couple of stops so that your shadow areas are exposed further up the curve, where the tighter grain is, and then print down to your desired look.

 

Here's an example:

store1.jpg

This is a flat scan of a 6x7 neg, highlight areas over exposed.

 

Here it is printed down:

store2.jpg


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#12 John E Clark

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Posted 10 November 2014 - 01:21 PM

I have used the Zone System for my way of thinking about the overall process of evaluating a scene to final display. Since I began with B&W, stills, I used the system pretty much as it is well documented.

 

However, there are modifications for the type of medium one is using. The negative has the ability to record a density range, aka dynamic range greater than the output, aka the print, for most situations. Print paper range was about 7 stops.

 

In the case of B&W stills I could, and did process the film negative by hand, printed the print by hand, and so I could perform various 'adjustments' at each stage of the process. Ultimately... I could burn and dodge areas of the print

to bring in detail, should the negative range exceed the print range.

 

The point of the Zone System is to 'know' what to expect from the process. In the case of motion picture film, while some of the principles are the same, the amount of control one has over the internal process is less than for stills (for example hand dodging

at the end to correct for excessive contrast range or under exposure in shadow areas...).

 

One's metering of the scene follows that process of expectation.

 

I use a spot meter for this sort of situation, as I definitely could not use an incident meter as the light sources illuminating the bill board were on the bill board, and while I could meter the light falling from the street lights... it is just not really the

appropriate tool for the job.

 

So, in the case of my billboard at night, I would meter the bill board and 'place' that value at 'near white. Since I was using a digital camera, and know that in the case of DSLRs I have no 'correction' if I saturate the sensor, so, I need to 'protect' the high values.

 

In that case the 'dark areas' fell where they did... and so, I may be required to 'boost' the shadows with some form of 'curves' in Photoshop (or in the case of digital Film use 'curves' in Premiere.).

 

For Film film the rule of thumb was to expose for the shadow, develop for the highlight.

 

So, I would meter the shadow, set my exposure for the values I wanted the shadows to be, and then meter the bill board, and 'know' that given where the shadows were, I would have to 'cut' development by 1 or 2 stops to keep the high values with

in the range of the ultimate print values. (Tended not to use a 'softer' paper to print a wider contrast range, as the 'softer' paper never seem to give me a 'rich' black as when I printed on 'normal' paper.)

 

These days, even shooting Film film, one usually scans to Digital Intermediary, and so, one can have far more control over the intermediate processes than before. So, one can not only change the contrast range to match the output, but with 'power windows'

or selective application of curves to regions of the image, one can essentially do 'burn' and 'dodge' operations on the negative. (There may have been motion picture total film processes that could do this in the olden days, but I would think they were expensive

for anything but 'preflashing' the negative stock which was used to 'boost' shadows a bit for low light situations.).

 

So to sum up... for Film I would meter shadows, set exposure, develop/print for highlights... and needless to say, there may be compromises that require more work in the process...

For Digital Film, until I use cameras that have near Film film 'dynamic range', I would expose for the highlights, and adjust curves for shadows, all with an eye for 'least grain/noise' given the situation... and some situations just aren't going to work...

 

As for specific meter readings... for the bill board... Sign Board == near pure White Zone 7-8, that is 2-3 stops more open than the meter reading. Deep shadows near Zone 2-3, that is 2-3 stops under the meter reading.


Edited by John E Clark, 10 November 2014 - 01:25 PM.

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#13 John E Clark

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Posted 10 November 2014 - 01:34 PM

Ran out of edit time... I was going to add, that these days I use the IRE display in Premiere to act as my 'digital densitometer', and so I 'center' my middle 18% grey, on an IRE reading of 50% (some people say 45%...)

 

And so, the White Bill Board would be about 85-90%, and the Dark Shadows would be 20-30%, again for what is reasonable for the output display, typically computer or consumer TV display...


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