Film/Camera tests

[harryprayiv]

It's the beginning of a semester for me and I'm preparing to start learning the characteristics of the different kinds of film that are available to me.

 

Even though I am going to be using various 16/S16mm cameras for a long, long time over the next few years while I get off the ground as a cinematographer, I have decided to test various kinds of film against eachother with rolls I recieve from RGBcolorlab in Hollywood, CA with a still 35mm SLR camera set to 1/50 sec or (as I hear) at 1/60 (because 1/50 isn't an option on most SLR cameras). I am looking for advice on what kinds of charts I should get that will allow me to learn each stock's

• exposure latitude (my main area of interest in these tests)
  
• color reproduction characteristics
  
• resolution (although not entirely important since I realize that the slower films are higher res...but it might help me to get an idea of WHAT low speed films handle details the best)
  

My shooting plan is as follows

 

I intend to light the card to something near a 5.6/8 split since I hear that this is the "sweet spot" of most lenses (and since it looks like the point where the aperture is at its most circular, to me, I think it would be the way to go as far as shooting...) .....correct me if my deductions are wrong there. I intend to use various densities of ND over the camera lens to match all of the kinds of films instead of changing the aperture, which I have deduced could have an inverse effect on the consistency of my tests.

 

Now, my main question has to do with the test card I should use....I have found this chart on B&H and it seems to be reasonably cheap and good. I don't really understand if the seperate steps in this particular (and other) grey scales have anything to do with seperate stops or are they closer together in steps than I imagine? Maybe each shift between one grey and the next is closer than a stop? I don't know...but I'd sure like to find out before I waste my money doing these tests only find out that the latitude of the films I am working with goes waaaay beyond my chart's scale...I have a hunch that is does, but we'll see. I hope John steps in to answer my question on this one.

If anyone has any suggestions and comments on my ways of thinking about any of this, please speak up because as you know, there is VERY little information on the web about this specific topic and I am at a loss for the accuracy of some of my deductions.

[John Pytlak RIP]

The Kodak Q-14 Test Chart was developed for graphic arts (printing) evaluation. For motion picture and video color evaluation, many cinematographers use the Macbeth Color Checker:

 

http://shop.store.yahoo.com/cinemasupplies/grayscalandc.html

 

The latitude of color negative film far exceeds the tonal range of any reflective test chart. Usually, latitude is tested using an exposure series (e.g., -3 to +3 stops with the Macbeth test chart).

[harryprayiv]

Thanks for the prompt reply, John. That helps a lot. Is there anything that would allow me to squeeze the entire latitude of a film stock into one frame so that I could compare many stocks side by side?

[David Mullen ASC]

You could compare your most over and underexposed frames to see the latitude at each end. One chart at one exposure isn't going to show you the real latitude.

[John Pytlak RIP]

One test that the Kodak team headed by Image Scientist Roger Morton developed was to include shiny spheres of various metals (silver, gold, copper) in the scene. The very shiny metallic reflections of the lighting require excellent latitude to fully capture the color and detail.

 

Here is a link to the SMPTE Paper they presented:

 

http://www.smpte.org/members_only/library/...file=morton.pdf

 

(SMPTE Membership required to access the on-line SMPTE library)

 

I recall the article was published in the Feb/Mar 2002 issue of the SMPTE Journal.

 

An illuminated transparancy (color filters and extended gray scale) can require a wide latitude to fully capture, e.g., a 3.0 density step tablet has a 10 stop range of density.

[harryprayiv]

An illuminated transparancy (color filters and extended gray scale) can require a wide latitude to fully capture, e.g., a 3.0 density step tablet has a 10 stop range of density.

I bet such a chart would be more expensive than my means allow, huh? (MY means being under 70 dollars maximum). If not, where do you think I could get such a thing?

 

 

Anyway, I think I will just eventually end up going with David and your suggestion of shooting one exposure right on, one 3 stops under, and one 3 stops over.

Do you think this technique would cover the latitude of the newer Vision 2 stocks? Because I hear that the 7217 (Vision 2 200T) has 11 stops of visible exposure? I ask because the gaffer on the recent feature I worked on where we used it said that there was really more like 5 or 6 stops of latitude...he said that he prefers the 7279 to the 7217 even though the grain is vastly improved in the Vision 2.

[John Pytlak RIP]

When running an exposure series, most use one stop increments. Therefore, a -3 to +3 stop series would be seven conditions: -3, -2, -1, N, +1, +2, +3.

 

Silver neutral density step tablets are available for use in transmission type targets. Here is a 3.0 density step tablet with 21 steps:

 

http://www.bhphotovideo.com/bnh/controller...ku=28980&is=REG

 

3.0 density represents a brightness range of 1000:1.

 

Each of the 21 steps represents a 1/2 stop change in exposure.

[Dominic Case]

Because I hear that the 7217 (Vision 2 200T) has 11 stops of visible exposure

the gaffer on the recent feature I worked on where we used it said that there was really more like 5 or 6 stops of latitude

Don't confuse range with latitude.

 

11 stops of visible exposure means that the filmstock can record that range of brightnesses: in other words, if the shadows in the corner under the table read on a spotmeter at 11 stops lower than the sunlit white wall opposite, then you will still see detail in both, at the same exposure setting.

 

Latitude of 5 or 6 stops means that, for a given scene (that bit is important) you can vary the exposure up or down by 6 stops in total and still recod detail in the whole tonal range you are interested in. Any film stock has more latitude in a flat scene than in a high contrast one. But obviously you have more latitude in any scene if you use the Vision 2 stocks (with about a stop more range than the earlier stocks).

[harryprayiv]

Because I hear that the 7217 (Vision 2 200T) has 11 stops of visible exposure

the gaffer on the recent feature I worked on where we used it said that there was really more like 5 or 6 stops of latitude

Don't confuse range with latitude.

 

11 stops of visible exposure means that the filmstock can record that range of brightnesses: in other words, if the shadows in the corner under the table read on a spotmeter at 11 stops lower than the sunlit white wall opposite, then you will still see detail in both, at the same exposure setting.

 

Latitude of 5 or 6 stops means that, for a given scene (that bit is important) you can vary the exposure up or down by 6 stops in total and still recod detail in the whole tonal range you are interested in. Any film stock has more latitude in a flat scene than in a high contrast one. But obviously you have more latitude in any scene if you use the Vision 2 stocks (with about a stop more range than the earlier stocks).

Thanks for that info. I better go over sensitometry in a practical setting more before I try and hang with the big guys.

[Bob Hayes]

Take good notes. I recommend placing a slate with the film stock, stop, and exposure setting (one stop over for example) recorded on it in the corner of your frame. Place a gray chip chart next to the slate. A color chart might also be a good idea. Make them large enough to read but don?t block too much of the frame. Use a spot meter to check different exposures in your shot. I draw a sketch of the shot and write on the sketch what your different exposures are. I try to meter and notate around nine stops of range. -4, -3, -2 , -1, 0, +1,+2, +3,+4 . You really want to see where you lose detail in your whites and where your blacks start to lose detail. These kind of tests really helped me build confidence in under or over exposing the image. Then have the lab print your negative twice. Once without correcting for under-exposure or over-exposure and then have them make the images match as closely as they can.