"Low Key," Weekly Photography Assignment for 22 - 28 March 2010

[keithsnell]

This assignment can be considered a follow-on to our previous "High Key" assignment.  In that assignment, I described how the term "high key" describes an image with predominately light tones, and stated that high key images are often used to produce a dreamy or ethereal mood.  Scenes that lend themselves to high-key treatment are low contrast and evenly illuminated, for example a snow scene under flat light, or a landscape enveloped in fog.  For the high key assignment, I mentioned that the photographer would probably need to over-expose slightly from their camera's recommended exposure reading, taking care not to "blow out" or clip significant areas of the scene.  (Our goal was to attempt to keep the tonal ranges in the image primarily in the upper half of the RGB values.)

By contrast, “low key” images emphasize the dark tones, and impart an ominous or mysterious feeling and are used to convey drama or tension.  When exposing a low key image we should attempt to keep the bulk of the tonal ranges in the lower half of the histogram; however, there should be detail visible in the dark tones. While this is not intended to be a "Zone III" assignment, you can see from referencing the attached Zone System diagram that Zone III (typically two stops below "mid-tone") is the darkest zone where we can reasonably expect to see clearly visible detail in the image.  Therefore, our "low key" image should primarily be composed of tonalities in Zones III and IV.

                                          Zone I        Black without any texture
                                          Zone II       Black with slight suggestion of tonality
                                          Zone III      Darkest areas that still retains visible detail
                                          Zone IV      Average shadows in landscapes/portraits
                                          Zone V       Middle Gray - 18% gray card
                                          Zone VI      Average Caucasian skin
                                          Zone VII     Lightest areas that retain visible detail
                                          Zone VIII    White areas with slightly visible textures
                                          Zone IX      Glaring white surfaces - Highlights
                                          Zone X       A light source (maximum white)

Sheila Ancheta's Looming Storm image was a great example of a low key image:

Looming Storm
Photographed by Sheila Ancheta

Please upload your images to the "Low Key" album in the Weekly Assignments category of the Gallery no-later-than midnight, Mountain Time (GMT -07:00) on Sunday, 28 March 2010.

[Michele]

I'm going to share my idea of what I wanted to do for this but I can't find a doll house.  

I wanted a doll house in very low light with a red light lighting it up from the inside of a window, (possibly with a sillhouette of Barbie inside the window)  In hard times, we all do what we gotta do (even Barbie).  A joke...  but nobody had a doll house to lend me and the only one Lauren has does not close (I made it out of shelves).

Oh well, maybe another time.

Is it normal that a camera has a hard time to focus in low light even if the lens is made for low light?

[keithsnell]

Great idea for your image.  Perhaps you don't need a doll house but just a "window" and barbie?

Yes, it is normal that a camera has a hard time focusing in low light.  Having a lens made for low light definitely helps, but below a certain level, most cameras will have a difficult time focusing.

You can get a "relative" sense for how well your camera will do in low light through the specifications.  The autofocus in the 50d is supposed to work (with the center AF point, which is more sensitive than the others) down to light levels of -0.5 EV.  By contrast, the new Canon 1D Mark IV is sensitive down to -1.0 EV.  Since EV is a logarithmic scale, the difference between -1.0 EV and -0.5 EV is greater than it would seem from just the numbers.  To give you some sense of how low -1.0 EV is, the light on a landscape from a full moon is about -2.0 EV.  

There is a mathematical relationship between EV and candelas per square meter.  (A candela is roughly equivalent to the intensity of light emitted from a single candle)

EV	cd/m squared
−1	0.063
0	0.125
1	0.25
2	0.5
3	1
4	2
5	4

   

However, it is tough to judge "candelas," and the best way to get a sense of the associated light levels is by comparing EV to "real world" lighting conditions, i.e., -2 EV = moonlight on a scene,  5 to 7 EV = "normal" home interior lighting with artificial lights, 16 EV = Snow in full or slightly hazy sunlight, 12 EV = areas in open shade, etc.

OK, probably more detail than you wanted.  

Maybe a better way to understand this is that at ISO 100, using an aperture of f1.4, light levels equivalent to 0 EV will require you to have a 2 second exposure.  Using a lens with an aperture of f2.8 will require you to have an 8 second exposure.  So, if the light levels are such that your exposures at ISO 100 are equivalent to f2.8 and 8 seconds, then your AF should still work (if the subject has enough contrast).  If the light is dimmer than that, your AF probably won't work.  Does that help any?

It also helps to have "detail" or contrast for the camera to focus on, so sometimes you can focus on a higher contrast part of the scene (that is at the same distance as your primary subject) and then recompose.

[Michele]

Yup, that's pretty detailed, but it has just been cut and pasted in the SOP.doc as a reference guide.  That did not all just come out of your head right?  You are a walking, talking Lexicon of Photography, aren't you?

Thank you, Keith.  The problem I had was with the apple, that was why I had to manually focus, but the candles were easy as pie (as long as you can buy the ready-made crust)

Have a great evening. 

Maybe I will try the Barbie shot tomorrow evening. I did make a window in Lauren's doll house but it is much smaller than Barbie.  (By the way, my child likes Barbie and people have offered her some as presents, but I hate the ... the doll.  It makes me feel, hmmm, inadequate.  She likes to leave them on the bathtub sill.  I get to see them everytime I am in the tub.  Barbie has suffered many a drownings when Lauren is not around.   

Barbie doing tricks is kind of funny, so maybe I will try it.  Bye for now.

[Michele]

Another question.  Would this technique "Painting with light" also qualify as low key?  I'm thinking not of light laser but a difused light that would create a rhythm on a subject.  (Not like neon, more like rennaissance)

Just curious again.

[keithsnell]

Yes, I think a relatively dark scene where you "paint with light" would qualify as low key.

Keith

[Michele]

Here was one of the first attempts at painting-in the light.  Without diffusing the light, it gave the guitar a smoking effect.  I think this is funny so I added it here afterall.  I then diffused it with a toilet paper roll with paper taped to the end of it.  I held the light higher and moved it faster around what I wanted to highlight.  This is so cool because every photo comes out different.

Funny, right?

[keithsnell]

Here was one of the first attempts at painting-in the light.  Without diffusing the light, it gave the guitar a smoking effect.  I think this is funny so I added it here afterall.  I then diffused it with a toilet paper roll with paper taped to the end of it.  I held the light higher and moved it faster around what I wanted to highlight.  This is so cool because every photo comes out different.

Funny, right?

I can imagine some cool effects.  My first thought was to try to capture motion in the strings, with "smoke" from the light painting.  Thanks for posting this example, it helps us imagine the possibilities...

Keith

[Michele]

That would be cool.  Did not think of it at all.

[girod]

What happened to the image???.....I love it....feels like a very soothing ghostly tunes flowing deep from the self-playing guitar.....simply a beautiful art for the soul.....

[girod]

sorry, now I see the "smoking guitar"........my PC or internet connection must be just soooo slow......

[Michele]

I moved it to here because I goofed it up.  I thought I would show what happened when I did not diffuse the flash light.  Thank you for the compliment.  I am certainly going to try that stuff again, that's for sure!