Wednesday, January 11, 2012

Quality of Light

There's nothing really earthshaking or groundbreaking or anything that I know about photography, but I do seem to know a lot of what there is to know. Anyway: what I have to say has been said before, I'm sure, by more thorough and competent people than I, but I'm going to say it anyway. a) because that's what the blog's for, for me to write about what I'm thinking about, and b) because I already typed most of this in correspondence to friends, so it's already done, and I'm lazy.

Here's the first of probably many topic centric nuggets in the arena of photography.

What do I know about light? And how is that reflected in the images I make. I've been taking photographs for most of my life, and I have a immersive intuitive sense of what does what, but I also have a lot of schooling in physics and optics. On top of those, I've lately done a bunch of experiments into specifics of lenses and how they work in certain conditions.

So: light. In terms of a photograph, there's a lot more to it than people think. The obvious aspect is that you're taking a picture of something. The light goes from a light source, bounces off the thing you're photographing, and goes into the camera. Pretty straightforward, but very incomplete. Images built from mathematical models this way look very fake because there's all sorts of subtle issues that aren't included in that description. Here's a list:

-Light bounces around and back on itself and all over the place. A lot. If you've ever painted a room a color, and found that the result wasn't the same as the color you picked in the store, this is partly why. The light picks up color every time it bounces off something, and so after a while bouncing off of green walls for example, the green compounds. My rough guide is that in a room of a color, that color will double in intensity. (so: helpful tip: buy your color paint diluted by half from the color you want)

Further: this bouncing around of light means that you'll be getting light from all sorts of angles coming into the camera. Paying attention to this multiplicity of light and knowing how to control it and adapt to it is one of the finer points of running a camera.

-Light has different colors. I mentioned this sort of in the last item, but those different colors of light behave slightly differently. If you've ever played with a prism, you've seen this. Though not as drastic as a prism in most cases, this variability of color behavior is still present in the process of taking a picture. It manifests in the scene/subject, in the optics of your camera, and in the sensing (film/cmos/ccd/etc/silver plate/retina/etc...)

-There's usually more than one light illuminating a scene, and this light has differing colors (usually), and the sources can interfere with each other.

-Different objects absorb and reflect light differently.

-Lens/camera construction can have effects. Beyond the intentional aperture/focal length/shutter speed, there are more subtle issues of lens element interplay and how these interact with all the stuff above. How long a lens is, how well it rejects unintentional light (light not coming from your subject), how many times light encounters a boundary between glass and air during its journey, issues of the quality and nature of the glass and air, reflection off internal surfaces and interference issues steming from this, diffraction, and there's more but I'm getting bored myself.

-Intentional distortions created by the optics or artificial lighting (an extreme illustration would be a fish-eye lens, but there are many more subtle distortions). yes. That's not a complete list, but you get the idea, there's a lot of things going on.

So that's a little of the background to what I said to my friend below. The question was (and I'm paraphrasing): why is the quality of light in your pictures different than mine? (the person asking has a very good camera and lens setup, and takes excellent pictures. I'd never thought there was any qualitative difference, but once he asked, I looked at my pictures and his for a while and tried to figure out where the differences were)

I shoot during mid-day a lot, so there's a very clear crisp character to the light. it's very blue and very undistorted. I know the common wisdom is to shoot at the golden hour, but while that gives a nice amber tone to everything, and it sets things into relief (both things that are easy enough to do in post), it comes at the cost of dirty air, dirty light, lowish light, changing light, non-neutral light (amber), and it also forces you to take pics in a rush. oh, also: shooting when the sun is low increases the likelihood of getting light into the lens (sneaking by the hood because the sun is so low).

I shoot middle apertures (like f11-f16).

I shoot prime lenses. -the best I can get. and there's different ones that work with different kinds of light. they all have their own color casts and distortions.

Lens hoods!

I underexpose most of the time, and I also take brackets almost all the time.

low iso's.


...I'm just guessing, but I see a lot of chromatic aberration in your shots, (hard to know on facebook), but that could be from too wide an aperture or lack of a lens hood (or light getting into the lens anyway). could also be backlight coming through the viewfinder. (it could also be from a crappy lens, but I don't think that's the case.)

anyway, like you, I take tons of pics and my hit rate is probably about 1/300 or so.

wow, this got long. think I'm going to post it on my blog.

hope it helps.

So that's what I said. I thought about including example pics with this article, but something in me told me that it's best not illustrated. Not sure why, but that's my intuition. Plus, I'm lazy.

The discussion does bring to mind one issue of interest (to me anyway): there's a common wisdom that it's not the camera, it's the photographer, and that a good photographer can get a good shot with any camera while a bad photographer will produce crap with the best of cameras. I think in general that's true, but of late, the 'crappy' camera has become an automatic camera. And that means that a good photographer can't make it do what he wants, and a bad photographer can get the same shots as anybody else. Auto cameras are pretty good, but to get the control you need to get really good shots, you have to have a good camera. And in this day and age, that means one that lets you control all the things possible, and that means expensive. So to a small degree, a 'better' camera does mean better photos.

If there seems to be any interest in these sort of photo essays, I'll expound on one, and I've got some other topics similar that I might cover. Let me know.

If you're curious: here's some of my pictures: Dave's pictures

Thanks for reading,
Dave DeHetre


  1. here's a comment thread from my facebook page:

    EK: nice post. agree with everything. its nice to see someone who has a different primary job than photography & gets what the majority of ppl dont get in modern days since dslr's became available. masters spent their entire lives wrapped up in only one thing (app, ss, light) but these days most ppl think its just the price of a camera. thats not even mentioning masters of printing like ansel adams & the leaps he did. a few comments:

    light bouncing around/back/different directions is scattering (just mentioning cause an old prof of mine used to grill me to use photo terms & one day i caught him not using scattering lol plus its a big thing in light.

    light color - the least acknowledged thing in modern day photography. the most difficult shots can simply be shooting people in a large room full of mixed bulb lighting...regardless of the light you are controlling. one job, it took me 3 days just to hand mask & correct 3 photos of a big wig because of the different bulbs in different fixutres in this banquet hall. the best solution, a mentor of mine once told me is if you cant beat the light, join in this situation, the best would have been to slap warm color filters on my standard cool color elinchrome lights - then in post, correct the entire thing globally. if you wanna see this in person, go to the kansas union on campus, to the top floor in the ballroom & take a few shots of an people in that room.

    light can never be figured out mentioned something like this. its true because its so wild & there are so many anomalies that exist that break phyisics laws. light waves & sound waves are consistently the breaker of normal physics laws even moreso than nanophysics, macrophysics or quantum physics. annomalies are all over the places. for example in sound, there is something called an acoustic shadow. this exists in light as well so you can kiss that light goodbye no matter what you do because of this & other oddball things light does. ive studied almost eight years specifically for complex lighting & it still is an on spot/in field thing to work out. the only way i explain it to people who asks is that its like math only in that if you know what + does, what - does, what x, does or what / does thats a formula for anything that comes at you in any situation or artistically what you want. there will never be a set group of rules.

  2. ...continued:

    i never shoot in mid day & the reason why the golden hour is so well known is not just the dirty light & the things you mentioned but its because of light scattering & the angle the sun is towards the earth at that particular time. its a beautiful light cause the shallow light comes in, bounces of the earths surface, bounces back down & all over the place scattering. all the negative things you mentioned can be controlled in a foreground shot with photo lighting a model or a statue can be shot perfectly colored, not dirty at all AND you get the gorgeous back ground light during the golden hour. plus lots of desirable anomalies happens because of this as well

    so many negatives during high sun light including hard light, hard shadows, too cool light, etc, etc. i just think the positives for a lower angled sun outweighs the positives of a mid day sun by about triple in my experience.

    absolutely right about lenses. even the same lens produced by the same manufacturer but from different factories will produce different results. a bulk of my learning was going through ken rockwells site in his lens section. hes a nikon guy, & it blew me away realizing the differences in nikon lenses against themselves. hes a great writer in layman terms & as a working photog in the field.

    11-16 fstop is a little too closed for me. ive heard that the best is 5.6-11 BUT even saying that i never limit myself. fstop as with light, i decide artistically on the spot, sometimes in photo groupings or even to each frame. i do tend to lean towards being more open most of the time though. i.e. 1.4-8 fs. bad habit? good habit? who knows. lol

  3. Dave DeHetre ‎@EK: wow! well, yes. that's a lot of stuff I never thought about. to answer that last part: the context was that my friend was asking why my pics looked different than his, and the noon-time, small aperture, etc... were just the things I do that contributed to the look. I don't think it's better necessarily, it's just different. Fact is, I shoot mid-day because that's when I have time, but I don't find it's as bad as most people think. And the other guy's images had a lot of near angle incident light flaring out parts of the image, mostly (I think) because he's shooting around dawn most of the time. --anyway: it was a big part of the difference between his shots and mine. His are really good, so it's not a matter of better/worse. In fact: what I was trying to convey to him was that it was just a difference, rather than mine being better. regarding the f-stops, I do like a pic with a little bit of diffraction going on. it's a nice subtle sharpening that makes things pop, so usually I'll go just a stop or two from smallest aperture (all else being equal). I've only just (in the past couple of weeks) started using strobes, so that's a whole new thing I'm trying to figure out. makes some things easier, and a lot of things more difficult. lot's of fun for sure! I'm going to post this stuff over to my blog if you don't mind.

  4. Dave DeHetre here's a good example: noon, f16:

    Dave DeHetre I think this is the shot that got me hooked on small apertures. it's at night, and f16 or so: