A couple of question from readers of the Lighting Field Guides came in last week that I wanted to share here. No matter if you grabbed one or not you may find it interesting - or at least amusing. For illustration purposes I'll use an image that I shot for those eBooks but don't think I used. Maybe I did - I forget.
There are two things I talk about a lot in the first two editions. The biggest is lighting ratios. Hopefully not in a pedantic way but more in a feel way. I do say that it's really important and learning how to manipulate it is one of the most important things you will ever accomplish in the never-ending quest of capturing light. The other thing is color temperatures of light - especially mixed sources.
My attempt to separate the shooting wheat from the post-processing chaff is a tall order but one I feel strongly about. Hence not doing any in the eBooks. You have probably noticed I consider myself more of a shooter than a post-processor. I actually resent post-process fine tuning being dumped in my lap for the most part. Heck when I shoot for spec work I almost never do my own post. Just not interested. In any case I may have confused a couple of folks out there as to the importance of post processing. It's crazy important. It doesn't have to be massive but it's crazy important. Just like having a great lab with people that are really good at color correction is when shooting film. Don't for a moment think that some OOC image is going to cut it as a final product. It's not.
Let's knock-out my comments on color temperature related to why I cannot stand un-gelled speedlights mixed with most ambient sources that you will encounter day or night. I talk a heck of a lot about my decision not to gel them in Simulating Sunlight and why that's all wrong. What I didn't do is actually show visually why. My bad, so here is a quick visual demostration of what I am talking about. Specifically fill being a bunch warmer than the main light. The image at the top is pretty much balanced to dead neutral for the speedlight which in most context is going to be very cool. I can see that the shadows are crazy warm and crazy green - not a look I care for in the least.
This next image is exactly the same but making the shadows lit by ambient dead neutral…
In my book that difference is spectacularly huge. It's not the fact that the two color temperatures are so so different. My big issue is that they are completely opposite of the way I actually like my images. I much rather a warmer main light source and a cooler fill. Somehow the inversion just looks all wrong to me. It's an easy fix but something almost nobody that shoots casually does - gel your speedlight. My speedlights at the power level I usually use them need somewhere between a 1/4 to a 1/2 strength CTO to look "right" to me. Not to match arbitrarily and exactly any ambient to them technically but in most conditions to be warmer than ambient fill. My big-boy lights need less and are absolutely consistent across all output levels.
Moving on to lighting ratios. I am going to paraphrase and modify the specific question that came in to make it a bit more general. It was about "fixing" lighting ratios in post processing. From my somewhat religious perspective - no, don't even bother. This is the last thing you want to do in post. Hence in my mind it's the first thing you want to think about when shooting. As usual I am going to try to demonstrate why this is in a rather oblique fashion. Rather than show you how forked up I can make something look by trying to "fix" the lighting ratio in post I am going to show what I hope might be considered night and day differences with this same image by using one really simple knob - the exposure knob - to a tiny degree…
The image at the top - the one that is dead neutral to the speedlight - let's see what that looks like with one third stop more exposure in post- hey that's the smallest increment on your camera right?
Okay - how about one third of a stop less…
Holy shit batman, that's a huge difference with a tiny little nudge on a tiny little knob. Combine that with the range between two "dead neutral" color balances and whamo you have an image that is not only on different planets but are in different galaxies. Which one is "right" - not for me to say. All depends on what you like. My own bent is probably a tiny tiny bit "less" exposure maybe a tenth of a stop in post or a two tenths and a tiny tiny bit warmer and pinker than flash neutral for this particular image.
Why do they look so so so so different than the OOC + one preset images that I used for illustrations in the field guides? Simply because I did not adjust them to even this degree which for absolutely sure I would if they weren't an academic exercise. Just went with the standard preset - good bad or indifferent along with the "fading" which I don't really like. I guess that's one of my pet peeves with instructional materials that discuss "shooting" and lighting and clearly have 413,000 more post processing adjustments than we just went through but leave all that out - as if the person shooting the camera is somehow "magic". Yeah right.
Okay - so you could look at my illustration with a tiny little knob and the huge difference in results as some sort of contrary evidence of "fixing" lighting ratio in post. As in hey - "hey man a tiny adjustment like that third of a stop can make things so so different then some massive shoving around of the histogram could get me anywhere". Sure - you can shove pixels around a whole lot more than this but consider for a moment that the shot above would be what I used to illustrate one end of the spectrum of "normal" idealized lighting ratios. Specifically a 4 to 1 ratio or about 2 stop difference between fill and main. You know how often that idealized normal happens in the real world randomly snapping images with not a care in the world - never.
In my oblique way what I am trying to say is that all this post stuff has a huge effect and should be considered fine tuning. Thinking you can post process your way to completely different ratio lighting ratios than you shot is a fallacy. Do images look way different with different shadow density, highlight fine-tuning, curve tweaks, and minor color balance differences - absolutely. They are critical. If this image can look so so different shot at the same ratio with tiny bits of fine tuning that didn't even do any other stuff that is in no way evidence that any old lighting ratio will look like any other with enough post fixes.
Here are a couple of corollaries and truisms to take away.
- There is a big difference between scene contrast and post-processing contrast. Separate and distinct things that have separate and distinct effects.
- The technology of photography and various "post-processing" techniques of all sorts though out the ages have been heavily focused on rendering a high-contrast world onto a low contrast medium in an attractive way. The general recipe that becomes way way over-complicted is shoot in a reasonable contrast ratio and render with shitloads of mid-tone contrast. The relatively narrow technical options on doing that produce drastically different end results. One of the reasons this image shows such drasticly different results here with "tweaks" is because it was shot a a fairly low ratio for the real world but a fairly high ratio for "normal" photographic ranges.
- The lower the lighting ratio that you shoot at will give you far more flexibility in the way you can choose to render final output.
- You can boil the whole technical exercise down to shoving all the tones toward the middle when shooting them and then rendering the output you want. Kind of depressing if you think about it like a computer. On the other hand realizing that the slight variations on how you decide to do that when you are shooting are a lot of the aesthetic art part of this thing (obviously combined with framing, composition, timing, etc - all part of shooting).
- Conversely how you choose to deal with situations where you can't shove all those tones toward the middle when shooting is also the interesting part of photography. At least to me.
- All the snake oil techno shit/babble/bull in the world that somehow makes you think you can just ignore all this and deal with it later automagically is just pissing in the wind.
Hope some other folks besides the above mentioned readers that emailed me about ratios and color temperature "inversions" found any of this useful. Just as a note - I did answer the specific questions with specific practical answers via private email. Hey - where can you get a bargain like that - personal answers for less than five bucks??