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Friday, September 19, 2008

Lighting Q and A, 9/19/2008

Looking through the questions that have come in so far, at least a dozen people have asked about the process of shooting manual flash without a flashmeter. So we are going to hit that one in depth today.

Like a lot of pros, I have made the switch from shooting with an incident meter to winging it and chimping off of the TFT screen on the back of the camera. Hit the jump for the how -- and the why.

The condensed version is, it comes down to working by numbers vs. working by feel. Or rather, by sight.

People who work in studios -- or photographers who want highly accurate and repeatable lighting schemes -- tend to like the comfort of f/stops displayed numerically. Measured right down to a tenth of a stop, they offer precision and repeatability.

And, truth be told, if I were going to set up 27 catalog product shots in a day I would probably let the meter do the driving. It is a different kind of shooting, and a meter is very well suited to repetitive and/or studio work.

But as someone who tends to be more of a location shooter, my first thought is always what I am going to do with the ambient. So the ambient exposure makes a much more logical starting point for me than does some magic f/stop revealed by a meter after I pop my flash.

I cannot remember the last photo I made where I did not take the ambient into account. Even if I wanted to nuke it, I needed to know where it was before I knew where to expose my photo to be safely above the ambient light level.

So, what I usually do is to make a frame on aperture priority, at an f/stop that would be a good working aperture for my final photo, in daylight white balance. This gives me two things: An ambient exposure reference point and a light color temperature reference point. For example, fluorescent lights will look appropriately green on daylight WB. I want to know exactly what ambient I have to work with.

Then I chimp my exposure and see how far, if any, I want to drop the ambient down before adding my flash.

My next step is to move to a faster shutter speed and see what that does to my photo. It's just like the Nick Turpin walk-through last week -- the ambient is not there to be an end-all "proper" exposure so much as to establish the floor to my final lit, balanced exposure. The further I drop the ambient component (before I add flash) the more range and depth my photo is going to have after I light it.

So, as I drop my ambient exposure and chimp the results, I am looking at both the histogram and the image on the back of the camera. The histogram tells me if I am crashing into full-on black anywhere.



I may want to, I may not -- but the histogram tells me when it does happen by bunching a spike up on the left-hand side of the graph. In the photo above, the histogram tells me that the chopper is gonna go to a sillo, and that is fine. I am more concerned with keeping my sky in the lower half of the tonal range.

The right-hand side of the histogram tells me where my brightest highlight is. And that combination gives me the range of the ambient component of my photo.

But I am also looking at the image on the back, too. I am scoping that out to get an idea of the "feel" of the environment I am creating for my final photo. I also may shoot a frame on an incandescent balance, for example, just to see how the shifted ambient looks. Experiment. You are creating an environment for your lit photo.

Once I get my ambient tamed the way that I want it, I add the light. Chimping again, I can see how my lit subject fits in with the ambient I have laid down. Did I blow out any highlights with my added flash? The histogram will tell me -- and I would drop my flash's power or increase the flash-to-subject distance. (Or, close down my aperture and open my shutter to compensate for the ambient shift.)

In the chopper photo, I had pre-tested my flashes to look good at my shooting aperture before the helicopter lifted off. So all of my adjustments would likely come from tweaking the shutter and checking out the back of the camera. (More on that shoot here.)

Back to the process. If my highlights are okay, I am pretty much done with my histogram. In fact, in the photo above, the lit area is so small I am not even getting enough data to use the histogram to judge the lighting. I would judge it by camera screen alone.

I have chosen my ambient level, so now it is all about the image on the screen. It's just a matter of eyeballing the screen to see the relative range of tones between the lit and unlit parts of the photo.

Flash meters are all about numbers and precision. Going with the camera's display is all about feel and relative tonal values. And building your photo with the above steps is a quick and easy way to get right to the exposure balance that you want without wandering around your scene popping a Minolta meter. Just be sure to keep that histogram contained in the normal range. Unless you have decided you want it to fall off one of the edges for effect.

If you have some kind of a rigid recipe you are following, a flashmeter makes sense. But I get much more enjoyment and creativity out of "adding salt to taste," if you will. And that practice has made me a much more fluid photographer, too.

Instead of being married to f/stops and ratios, I now spend my time thinking about the feel of the photo's chosen ambient exposure level, and how I am going to shape and color my added light when I create my final look.
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46 Comments:

Anonymous Jonathan L said...

Hi David,
I am wondering whether you are shooting in RAW or JPEG mode as the histogram isn't accurate/reliable for RAW images. Nor is the LCD for color and lighting.

September 19, 2008 2:18 AM  
Anonymous Stuart said...

Hi David,

I use an EOS10D at the moment and I struggle to work this way. 2 Reasons: If I were to judge the image based on what my LCD screen shows me it would actually look ok when I know its underexposed and the second reason is that the histogram information is not accurate enough on this camera and should only be used a very rough guide and other cameras that fellow strobists are using maybe the same.

So when I chimp the back of my camera, I have a lack of confidence and generally end up with an image that is 1 stop under exposed.

I totally love the idea of working this way, but each time I shoot now, I am half tempted to get the light meter out to help me get to a safe starting point which I can then "add seasoning" to as I go.

Also, I understand what you are saying in this post but from a "beginners" point of view would it not be better to give an actual ambient example of shutter and f-stop / ISO and then another for the actual flash exposure plus what the flash is set at 1/2 power etc. Even if the figures don't relate to the specific shoot there is at least an example up there as a guide.

I have friends that read this blog and every-time you do a post like this, I then get 20 questions in the pub later, which I enjoy answering and breaking down for them, but it makes me feel that others must be asking the same question but don't have a mate like me to make sense of it.

Best Regards

Stu

P.S. Sorry for the long post and before anyone says it? I have a Canon EOS5D Mk2 on pre-order :)

September 19, 2008 3:01 AM  
Blogger Will said...

Could you define chimp? You always say "and just chimp it" and "then I chimp off the screen" and the like. What does that mean?
I think it's some middle ground between guess and estimate, but you use it a lot, so I've been wanting to find out what you mean it as.

September 19, 2008 3:47 AM  
Anonymous Brandon D. said...

Some people work better using visual feedback, others work better using analytical feedback. Even with film, polaroids aren't 100% accurate/reliable for determining the what will happen on film, but polaroids still serve as a visual guide for film photographers.

Using the LCD is like looking at a digital polaroid. Is it 100% accurate? No. But does it give you an instant feel for what you're doing during a shoot? Yes. The LCD also gives the photographer a chance review the composition, direction of light, and so forth.

David, thanks for taking the time to explain this technique.

September 19, 2008 4:25 AM  
Anonymous Jonathan Histed said...

In my somewhat basic use of the histogram usually for natural light shooting (usually split into 3 primaries as my canon 400D has a habit of just blowing out red on skin tones without telling you)-- I tend to worry about maximising the exposure prior to blow out; with the histo pulled down a bit if the subject is predominantly dark. This is largely motivated by a fear of the thermal noise and nasties if things get too dark (esp on slow exposures say at twilight). What's your "danger level" below which you start worrying things aren't so much being atmosphericaly dynamically ranged; as goig to hit the technical limitations of looking like rye bread going mouldy ?

From my perspective for the helicopter shot; I'm guessing my thought process would be; "under expose" by 1 to 2 stops to increase saturation in the sky; and to give a dramatic dynamic range when the flash component of the shot comes in, which will be exposed towards the right: so we're back to the "how dark do i risk"... prior to bringing in the flash?
With natural light shooting you rarely have to worry about "how dark can I go"---whearas with this methodology; you are setting the darker end; and then lighter end (with flash) (OK I know you can do it the other way round; e.g. using flash for fill.. but you get my drift); to maximise dynamic range: but it means you have to have more of a feel for what happens when things start to get dark....

Great, great post as always

thanks David!

September 19, 2008 4:48 AM  
Blogger Sascha Rheker said...

One thing one might add is, that as you are talking about flashes without modelling lights the picture on the back of your camera is a substitute for the modelling lights too.
A second point people constantly seem to forget, if they argue the pros and cons of flashmeter vs. using the camera's TFT screen, is the fact that in former times most photographers who used flashmeters were also shooting countless Polaroids.

September 19, 2008 5:18 AM  
Anonymous Anonymous said...

problem is as a previous commenter pointed out, the display is often not a good indicator as it may be too light or too dark to begin with, but the histogram should definitely give a better idea. i also shoot mostly on location but shoot a lot of portraits, fashion etc... so although i first get the ambient, i still meter for the main object (face etc...) because sometimes i am still surprised how it looks good on the screen but once imported into the computer, the result when not properly metered can be not too pleasant. of course one can always adjust but when setting up a shot in detail as opposed to documentary, how long does it take to use a meter?? it is done in no time, especially with wireless so i am not sure if looking at the screen is so reliable.

of course one gets to know ones equipment well and knows roughly what the result will be from chimping but, anyway, i shoot commercially and still always use my light meter, maybe i am one of the few left who do that.

thanks for the excellent work on your site D.H.

cheers

September 19, 2008 6:39 AM  
Blogger Mitch said...

Well Jonathan,
Judging by David's work, as well as thousands of shooters on the Flikr Strobist group, shooting raw, using the histogram, and chimping of the tft screen works very well indeed! Fine tuning can be done in Raw processing to correct any minor colour/exposure issues. Give it a go!

September 19, 2008 6:52 AM  
Anonymous Colby McLemore said...

Great post. I read a lot of posts here before I figured this out. It is in a very understandable readable format. Thank for everything you do.

September 19, 2008 7:20 AM  
Blogger Yanik Chauvin said...

HI Jonathan

Every time I get a new camera, the first thing I do is a few test shots that I then compare with my computer monitor and my camera LCD. Then I knowhow accurate my LCD is. I've never had a problem with color accuracy with my Nikon's.

As for histogram, I always found it to be accurate for my RAW files. Mind you, I haven't shot jpgs in a while to compare. ;)

September 19, 2008 7:47 AM  
Anonymous Patrick Snook said...

Hi David

Thanks for this. I had been curious in earlier posts about your term "above", referring to working above the ambient light. I could not quite get my head around that (it's bad enough that we talk fuzzy about "fast" lenses and "cool" blue light), and never wanted to be a pedant by asking . . . but here it makes perfect sense. You are lowering the ambient light level, and raising light again, or working above, with added light (strobes). Thanks! And for everything else your blog offers.
Patrick

September 19, 2008 9:03 AM  
Anonymous George Quiroga said...

I read somewhere that the Histogram representation on the back of the camera doesn't accurately represent the capture when shooting in RAW. It seems that it is based on a JPEG translation. I've noticed that difference myself and it is usually not a problem since the RAW image will have a wider latitude. Has this been your experience? Do you compensate for the difference?

September 19, 2008 9:09 AM  
Blogger Jerry Pennington said...

Great info. When I'm shooting outdoors, I usually set to shutter priority and set the shutter speed on whatever the max flash sync speed is, then see what kind of aperture it's giving me. From there, I adjust my speedlights to work with the aperture to balance everything out.

September 19, 2008 9:31 AM  
Anonymous Patrick said...

Hi David,

As a studio photographer I prefer using a tethered computer and the monitor to judge my exposures, yes even when I'm doing multiple catalog product shots.

September 19, 2008 9:37 AM  
Anonymous Trevor said...

Hi Jonathan,
I'd like to hear in more detail about the RAW histogram not being accurate/reliable as I shoot strictly in RAW. I don't like to miss anything when it comes to understanding the nuances of my camera.
Cheers!

September 19, 2008 9:38 AM  
Anonymous Stefan said...

I really feel that a light meter can help a lot when you're learning about exposure and flashes. I don’t see it as being bound to f-stops or ratios. Of course it’s not a necessity anymore (with digital), but I still think it’s a great tool to have in the bag.

September 19, 2008 9:44 AM  
Blogger Eli T. said...

Great post David.

@Jonathon
Personally I would always shoot something like this in RAW. And the point here is, not the absolute accuracy of the histogram and monitor but, training yourself to visually manipulate the light that creates the image. This chimping "skil" is crucial to me. Being able to quickly "improv" a great shot in a tough situation and get it as close as you can to what you want. You're going to tweak it in PS later anyway.

September 19, 2008 9:51 AM  
Anonymous Anonymous said...

Excellent post David and clears up a lot for me!
Debbi in California

September 19, 2008 10:13 AM  
Anonymous MrT said...

To the person that asked about chimping...here is the answer straight from wikipedia...

The term 'chimping' is attributed to Robert Deutsch, a USA Today staff photographer, in September of 1999 when writing a story for the SportsShooter email newsletter.

The phrase is most likely derived from comparison between the sounds and actions some make while reviewing images and those of an excited primate (Oooh! Oooh! Aaah!), or when a photographer is completely absorbed in the act of analysing, admiring or proudly displaying a shot to others.

Also, as far a not seeing an accurate representation in the LCD. Although simplistic, you could adjust the brightness of the display (check your camera manual)to offer something that is a little closer to what the histogram is telling you.

MrT

September 19, 2008 11:14 AM  
Blogger Andy T said...

"Chimping" is just holding the camera up and looking at the LCD screen - like chimpanzees do to mirrors :)

September 19, 2008 11:22 AM  
Anonymous Jonathan L said...

Hi all,
Well, my first question is a little provocative as I am shooting in RAW and chimping the LCD screen as well.
Just want to comment that the camera's on-board processor is used to generate the low resolution JPEG preview image that appears in the LCD screen. The histogram is also based on the JPEG preview and could therefore be a poor indicator of the true exposure potential of a raw capture image. But indeed, in post-processing corrections are easily made when shooting RAW

September 19, 2008 12:05 PM  
Blogger DerekW said...

Official Chimping Information:

http://www.sportsshooter.com/special_feature/chimping/index.html

September 19, 2008 2:16 PM  
Anonymous G. Chai said...

I have to admit that I am one of those who asked for clarification on shooting without a flashmeter. Thanks, David, for your explanation. This really made the light bulb in my head light up!

September 19, 2008 3:07 PM  
Anonymous Anonymous said...

For those wondering about RAW file capture, histograms and exposure these two short articles explain alot

http://www.adobe.com/products/photoshop/pdfs/understanding_digitalrawcapture.pdf

http://www.adobe.com/products/photoshop/pdfs/linear_gamma.pdf

September 19, 2008 3:59 PM  
Anonymous Staale S said...

It may be useful to know that the JPG preview that the histogram is based on takes into account your in-camera settings for colour saturation, contrast, image styles etc. The RAW file, by definition, does not.

The upshot of this is that in order to keep the JPG-based histogram as representative of the RAW as it can be, all the image processing parameters in the camera should be set as neutral as possible.

September 19, 2008 4:19 PM  
Anonymous Shamik said...

This is with regards to the reliability of the histogram and the image preview on the LCD screen.

As mentioned before, the preview on the LCD screen is based of the embedded jpg that every raw file has. The histogram also corresponds to that. For jpeg shooters that is all fine and dandy.
Now for Raw shooters, this can be highly misleading as this jpeg is based on the in camera parameters like sharpening, saturation contrast etc.
To be able to judge critical exposure(as a RAW shooter) i keep all the in camera parameters to their lowest levels and the brightness of the LCD to minimum.
I also look at the RGB histogram depending on the scene that i am shooting.
With all these things taken care of i dont have any problems judging exposure while shooting RAW and if there are any minor issues i know that i have enough headroom in the RAW file to correct it.
Chimping makes it so much easier :)

September 19, 2008 5:01 PM  
Anonymous Anonymous said...

Out of curiosity, when working in dim or limited light, and then raising the shutter aren't you going to send the image into about 5+ steps of under exposure. Thus, I'd think the histogram would be more crammed to the left.

Is my logic working here?

September 19, 2008 7:29 PM  
Anonymous Larry R said...

For those interested in the accuracy of the LCD screen image, this simple cure worked miracles for the usefulness of mine: Turn the display mode/LCD screen of your camera to an image that you know to be well exposed. At the same time, in the light that you generally sit in to look at your monitor, bring that same image up on the computer screen. This will work best if the room is relatively dark. Also, it is important that your monitor is well calibrated. (There are any number of relatively inexpensive programs that will suffice for that.) Now compare your camera's LCD image to the image on the monitor, and adjust your camera's LCD screen brightness control until you get the closest match possible to the image on your computer screen. My very strong guess is that camera manufacturers set their LCD screen default brightness higher than it should be in order to make it look clearer and more attractive to potential buyers. With my Canon 5D, turning the brightness control down one notch did wonders for the accuracy and usefulness of the images on its LCD screen. Before making that adjustment, yes, images that I shot based on the LCD image were about one stop too dark, because the LCD image had been about one stop (inaccurately) too light. I would bet that this helps immeasurably.

September 19, 2008 11:51 PM  
Anonymous Richard Cave said...

Subject luminance range was something we were told to use at college. Measuring the difference between high lights and shadows to create better tones. We used a incident light meter to work out the exposure. I am trying to figure out how to work it out using the histogram.

There must be a short cut to all this, I use chimping my self but would like to capture the full tones of a subject a bit more intuitively.

I have now fallen into the bad habit of shooting one stop lower (which can be brought back in by photoshop). My D2X display in sunlight is awful to read.

Is there any hard and fast rules that would make shooting a subject a little easiert to get better tones and prevent noise.

Cheers

Rich

September 20, 2008 12:47 AM  
Blogger Jerome Love said...

Thanks for the great post David. It is a great starting point, I have found myself so lost a shoot before just kind of guessing. I really appreciate how many questions this article cleared up.


Jerome Love

September 20, 2008 6:17 AM  
Anonymous azam mansha said...

great work on RAW or Jpeg format pictures i like this very much and i am also best editor. I know that that as you are talking about flashes without modelling lights the picture on the back of your camera is a substitute for the modelling lights too.

September 20, 2008 7:50 AM  
Anonymous Udi said...

David,
Thank you for this great post. This was one of the issues I found hard to tackle and always improved in "micro steps" so each session I had a better workflow. This post is not a micro step but a giant leap.

On a side not, what's your take, artistic and lighting-wise on locations where ambient is close to nill. I mean those places where to even considering using the ambient, you'll have to drop to 1/30 or so.

I just love lighting Q&A,
udi

September 20, 2008 8:09 AM  
Anonymous Fabiano said...

As i see it, even the lcd at the back of the camera not being totally acurate on either color or brightness/contrast or wathever, what you see on it can be easily obtained on post-processing that image. Even not accurate, what you see there is possible to get on your final image without too much trouble, so i think it can be taken into account when looking a image. In fact, i think sometimes the image tells more than the histogram itself...just sometimes...

September 20, 2008 10:40 AM  
Anonymous Anonymous said...

While the LCD screen on the back is not the best device for viewing your photos its the best we got!! So I work with it and make it work.. I have noticed on my 40d that when the image looks good on the screen its just about a stop underexposed. So to remedy this I have turned the brightness of my LCD screen down 2 clicks using the menu function and as a result my images more closely reflect what I interpret on the screen. I agree its not perfect but again my intention is to make the tools work the best I can make them work..

September 20, 2008 10:13 PM  
Blogger Sudhir said...

Hi,
Im a long time reader of this site and I thought I will add a few things to this post.

The LCD is quite inaccurate in terms of dynamic range esp the D70. The flashing highlight means any one channel could be clipping. It doesn't necessarily mean its blown out. Also the histogram mid on the D70 is not grey but 1 step over grey.
The multi channel histograms on the d80 etc are better in this respect. You also get a instant feed back of your white balance if you shoot a piece of white and looking at the histogram instead of judging the white on the histogram.

Now, In regards to using to light meter. You will need to calibrate your light meter to your camera before starting out. My Minolta flash meter which was accurate on film has to be set at 120iso when shooting 200iso with my d70.So unless you calibrate your meter, its no more accurate then the lcd.
Cheers,
Sudhir

September 20, 2008 11:40 PM  
Anonymous Tyler said...

I always carry my little pop-up gray card around in my back pocket and pop a few frames of gray to get more accurate chimping. The other side of the card is white for super easy custom white balance!

September 21, 2008 2:42 PM  
Anonymous Udi said...

I said 1/30? oooops! I meant 1/3

September 21, 2008 3:31 PM  
Blogger chris said...

The histogram displayed on the back of the camera after a RAW capture is indeed a representation of the pixel data spread across the dynamic range of the imbedded JPG Preview. In my opinion and experience the important issue to understand is that the limit of recoverable pixel data on the highlight end of the spectrum is significant in a RAW capture.
Some "features" of our current crop of digital cameras and the traditional way we are thinking about using them can lead to problems. For example as I'm out shooting under reasonable lighting and contrast levels I expose a frame, chimp the shot and receive that "helpful" blinking highlight warning on my screen. Hmm... I sure don't want to blow out those highlights. So what is my first reaction? Maybe I should drop the exposure of the frame by a stop. I do.
Here's the rub. In the old days the "data" on a piece of film was for the most part distributed evenly across the entire dynamic range. On a digital sensor the amount data collected is exponentially more in the top stop of the range as opposed to the low end. In a typical case fully one third of the data of an image is in the top two brightest stops.
If I back off a full stop from the dreaded blinking warning or god forbid two stops I could be tossing away one third of my image and the treat of shadow noise. No thanks.
In the end lighting is all about ratios and ratios do not necessarily change with exposure. This is but one of the reasons that no image is every at its best straight from the camera. Post processing is now a part of life.

September 21, 2008 6:25 PM  
Blogger Sudhir said...

I agree with chris.Also the histogram representation is based on the JPG after in camera post processing (sharpening , saturation etc). When my camera says blown out(blinking image), photoshop says 245,245,245.

September 22, 2008 1:20 AM  
Anonymous Jonathan L said...

@Chris:
This is the answer I was looking for. Thank you for clarifying this up for me !

September 22, 2008 2:12 AM  
Blogger Michael said...

I keep it simple. I usually just set:

- Exposure compensation: -2
- Flash compensation: +2

Obviously that's a starting point only, and I vary to taste, chimp, redo, etc. But as a starting point, it works well for me. Example:

Lighting example

Michael
www.mvwphoto.com

September 22, 2008 7:25 AM  
Blogger chris said...

Interesting proof of concept is to make a very dark Raw exposure then make a second near white exposure. Check the actual file size of each image. The highlight image will be a larger files size. This in my mind proves the model of pixel data distribution towards the highlight end of the spectrum.

September 22, 2008 10:46 PM  
Anonymous Anonymous said...

I still have no idea what chimping means. Looking at the LCD of my camera is rather vauge ; And doing what - scratching my head?

September 23, 2008 11:32 AM  
Anonymous Anonymous said...

@ Richard Cave

There is a way to get a head start on reducing noise and capturing better tones.

ETTR
Expose To The Right

This is written for K20D but the notes on this site should work for other cameras
http://daystarvisions.com/Docs/Tuts/K20D_Tips/pg1.html

Luminous Landscape also has some notes.

Basically, you figure out the highlight range of your camera (for K20D it is 3 stops) then meter the brightest thing in your composition. Use spot meter, dial in 3 stops over and your histogram is to the right.

Tanner

September 28, 2008 1:58 PM  
Blogger kevwil said...

This post alone will help me a ton. Thanks!

October 02, 2008 9:31 AM  
Anonymous evamedia said...

@anaonymous: chimping = take a shot, look at LCD decide it's too dark, open aperture(or move shutter speed) take a shot, look at LCD. Carry on until it looks right.

I pretty much do the exact same workflow as David, but without the whitebalance, just shoot on auto and change in Lightroom. Must try David's idea.

October 11, 2008 4:46 AM  

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