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Archive 2012 · Do I need a light meter?
  
 
jzucker
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p.2 #1 · Do I need a light meter?


agreed and the reason ETTL fails is because it's reading the reflected light so each flash's exposure will vary based off of what it's reflecting off. A manual, incident reading will be the same regardless of whether the flash is hitting black, white or red with green polkadots. I just took this shot wednesday with 5 flashes, all metered by hand. F8 on the BG, one at each side at F8 for rim lighting a beautydish above at F8 and a fill light at F4. Can't imagine how many shots it would have taken with ETTL. This was the (first) test shot. My wife was behind the model doing her hair and I extracted it and put it on a different background. Metered using sekonic L358.








Dec 21, 2012 at 09:52 PM
phuang3
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p.2 #2 · Do I need a light meter?


E-TTL was initially designed for reporters, because they don't have time to make adjustment in a heavily crowded scene. It could be useful for remote flash environment.


Dec 24, 2012 at 03:27 AM
Michael White
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p.2 #3 · Do I need a light meter?


Get one of the Sekonic mid range meters that will trigger you lights by wire if that is how you normally use them but if you use pocket wizard radios to fire your flashes then go for a model of meter that will accept a radio module to trigger you flashes individually and as a group.


Jan 11, 2013 at 07:13 AM
Graystar
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p.2 #4 · Do I need a light meter?


jzucker wrote:
Can't imagine how many shots it would have taken with ETTL.


That's probably because you likely don't use ETTL, and don't know the techniques utilized with ETTL. And when a person doesn't know the techniques, it's difficult for said person to understand how the system is utilized to accomplish various goals. The answer to your question is...rarely more than two with the method I described. And once the exposure is set and locked, you can change your aperture and the lights will adjust accordingly. With manual lighting the lights are driving your aperture. With ETTL, your aperture drives the lighting. That's what makes the system more versatile than manual control.

Also note that the OP is not in a studio. The reference here is to a small portable setup that needs to be moved around and set up quickly and easily. The equipment is already set...he's got two speedlights and controller. The question was asked within that context. And in that context, there is no way that setting the lights and camera manually, via a meter, is going to be faster than simply using a gray card with a targeted reference point on the histogram.



Jan 11, 2013 at 01:08 PM
jzucker
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p.2 #5 · Do I need a light meter?


i do understand ETTL . It has it's place but we shoot all the time on location with a meter (no need for a grey card) and have no problem with exposure. Admittedly it's a little slower but the quality of light we get from a large flash tube going into a large modifier trumps what you can get with an ETTL setup and a speedlite and image and light quality is more important to us than convenience.

And the point is that ETTL can be fooled easily and then you're left with making manual adjustments in the form of flash compensation which can change quickly in a location environment because the best the TTL metering can do is base it's exposure on reflected settings and pre-programmed patterns that the engineers have programmed into the system.

Other than Joe McNally (who's selling books and seminars) there are not a whole lot of great photographers using ETTL for the bulk of their portrait work IMO.

Graystar wrote:
That's probably because you likely don't use ETTL, and don't know the techniques utilized with ETTL. And when a person doesn't know the techniques, it's difficult for said person to understand how the system is utilized to accomplish various goals. The answer to your question is...rarely more than two with the method I described. And once the exposure is set and locked, you can change your aperture and the lights will adjust accordingly. With manual lighting the lights are driving your aperture. With ETTL, your aperture drives the lighting. That's what makes the system more versatile than manual control.

Also note
...Show more



Jan 11, 2013 at 01:53 PM
cgardner
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p.2 #6 · Do I need a light meter?


The goal of the exposure exercise is to record the same range of tone and detail you see. The way it is done indoors with two flashes (starting in a dark room) is to add enough fill to record the shadows at whatever f/stop the lens is set at, then overlap the key light over the fill until they are also reproduced correctly with detail in solid white just below clipping.

Back in the days of film the means to that goal was knowing the numerical key:fill ratio needed to fit a full range black/white subject (e.g. bride and groom) to the range of the print or transparency. For color prints that was a 3:1 ratio:

H:S
1:1 Even Fill
2:0 Key 2x (1-stop) brighter (incident)
==
3:1 reflected ratio.

On color film we would meter the fill (meter pointing at light from shadow position) based on the amount needed to record the detail in the black suit on the negative, then set the key light incident meter reading one stop brighter based on knowing that's what was needed to reproduce the white dress correctly. The result was a "normal" looking full range which was correctly exposed everywhere.

With digital the concept is the same (detail everywhere seen by eye) but the results can be judged visually. Try this:

Set your lens to f/8, camera 8 feet from full range subject. Spare the wife, just throw a black suit and white suit over a chair.

Start with flashes in M mode, Group A as fill over the camera and and Slave (key) in Group B off to the side an arm span between flash and subject. Set both at 1/128th power.

First raise fill to 1/64, 1/32, 1/16, 1/8, until you see detail in the folds of the black suit in the playback.

Now raise the power of the overlapping key light the same way until you see the highlighted parts of white shirt start to clip, then back down the power until it doesn't.

Note the group A and group B power settings. The same power settings will give you the same full range with detail everywhere at the same fill / key distances. Today, tomorrow, forever. It's the basic set-up I've used for portraits for over 40 years because it is predictable and consistent.

Next repeat the same "fit the scene to sensor" exercise in ETTL ratio mode.

Lens at F/8

Ratios on, fill over camera in Group A, Slave/key in Group B. Ratio set to A:B = 1:2 (2x more key than fill [incident]). Why 1:2 as the starting ratio? It should be very close to perfect at recording the entire black / white tonal range.

Now just shoot test shots adjusting FEC until highlights in white shirt are just below clipping.

Once the highlights are rendered correctly, check how A:B =1:2 is fitting the shadows to the sensor range:

Do you see detail in the shadows in the black suit? If not, change the ratio to A:B = 1:1. That adds more fill. The metering will adjust the flash output so a FEC adjustment after changing the ratio should not be necessary.

If the black suit is being rendered gray at A:B=1:2 (with FEC set for correct highlights) it indicates the 1:2 ratio is creating too much fill for your sensor range. Change the ratio to 1:3 which will reduce fill. Metering will adjust the flash power to keep the highlights correctly exposed at same FEC setting.

Upon completion of those two simple tests you will know both the manual power ratio and ETTL A:B ratio needed to fit a full range scene to the camera sensor range, without a meter. The difference?

In M mode the ratio and exposure will only be correct at the same distances between key and fill. Good for consistent shot-to-shot exposures but best suited for static shooting situations like formal portraits or still life.

In ETTL once you find the A:B ratio that fits the full range scene to the sensor range as you move around and your shooting and light distance to subject changes the metering sorts out how to keep the ratio and the exposure the same. Will in do it perfectly? No. You need to "chimp" looking at the highlights as a gauge and tweek FEC to keep them under clipping with detail. Err on the side of slight under exposure. You can make underexposed highlights correct in Photoshop, but you can't put detail back into blown one.

Now with that new understanding of your flash gear and camera do you still think you need a flash meter? If so and you buy it the exercises above will equip you with the knowledge to expose a full range in the event you drop and break it, or the battery in it dies (which happens unexpectedly at the worst times).



Jan 11, 2013 at 07:38 PM
jzucker
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p.2 #7 · Do I need a light meter?


cgardner wrote:
In ETTL once you find the A:B ratio that fits the full range scene to the sensor range as you move around and your shooting and light distance to subject changes the metering sorts out how to keep the ratio and the exposure the same. Will in do it perfectly? No. You need to "chimp" looking at the highlights as a gauge and tweek FEC to keep them under clipping with detail.


That's exactly my point. With incident metering, the light is the light. You can move around the subject and change the background, the clothes and anything else in the scene and the light won't change. With ETTL, you can be very specific about the ratios between key and fill and if you change your camera angle and happen to have (for example) sun highlighting off a body of water in the scene, your exposure will suddenly be unexposed.




Jan 11, 2013 at 08:32 PM
Graystar
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p.2 #8 · Do I need a light meter?


jzucker wrote:
That's exactly my point. With incident metering, the light is the light. You can move around the subject and change the background, the clothes and anything else in the scene and the light won't change. With ETTL, you can be very specific about the ratios between key and fill and if you change your camera angle and happen to have (for example) sun highlighting off a body of water in the scene, your exposure will suddenly be unexposed.


That's why there's Flash Exposure Lock...to lock the exposure so that it doesn't change.

People who work in manual everything see "locking exposure" as being able to maintain the same aperture and shutter/flash power. People who understand auto modes see locking exposure as locking an Exposure Value. Aperture, shutter/flash power, ISO...they don't matter as long as the EV is constant.

I can use my Nikon with High Speed Sync remotely. I can use my gray card to set exposure and lock it with FV Lock. Now that I have my EV locked, I can adjust aperture to control DOF, shutter to suppress or allow ambient light, and ISO if needed. And every shot will have the same exposure on the subject because the camera is automatically performing the same exact adjustments I would have made myself, were I shooting in full manual.



Jan 11, 2013 at 09:14 PM
 

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jzucker
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p.2 #9 · Do I need a light meter?


Once you lock the exposure, you are no longer using ETTL. If I want to change the DOF I can remotely lower the power to my flash from the camera just like you can. Or, I can change the shutter speed to suppress or allow ambient light just like you are describing using ETTL. The point is you're suppressing ETTL to compensate for what it wasn't designed to do - which is to measure the exposure based on incident rather than reflected light.

As I said, ETTL has it's place but again, the biggest problem is you are working with pin light sources with limited power and refresh capability.

I see so many photographers struggling to make their ETTL systems work like a studio strobe that I almost always recommend folks just pick up a cheap alien bees system instead. You'll spend less money and get better results and learn something about exposure in the process.



Jan 11, 2013 at 09:24 PM
Graystar
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p.2 #10 · Do I need a light meter?


jzucker wrote:
Once you lock the exposure, you are no longer using ETTL. If I want to change the DOF I can remotely lower the power to my flash from the camera just like you can. Or, I can change the shutter speed to suppress or allow ambient light just like you are describing using ETTL. The point is you're suppressing ETTL to compensate for what it wasn't designed to do - which is to measure the exposure based on incident rather than reflected light.

The ETTL system is being used as an initial setting that can then be locked, or I can decide to tie the exposure to a certain area of the scene...another exposure-control technique that I haven't mentioned. The important thing is that. I'm only dealing with the control that I'm most concerned with, and the camera is handling the rest. You can remotely lower the power of your light, but that's still a manual adjustment. I simply change my aperture and all the lights are adjusted automatically. The ease of my adjustment fosters experimentation, resulting in a wider variation in shots. The burden of your adjustment process discourages experimentation. If you have three lights and you want to change your aperture, you have to manually adjust three lights...and your aperture...and you have to dump your power if you opened the aperture. What a pain.


As I said, ETTL has it's place but again, the biggest problem is you are working with pin light sources with limited power and refresh capability.
That's true...never said or implied that the lighting was better. But the control over the lighting is definitely better.


I see so many photographers struggling to make their ETTL systems work like a studio strobe that I almost always recommend folks just pick up a cheap alien bees system instead. You'll spend less money and get better results and learn something about exposure in the process.
The problem there is that people are trying to just use the system without understanding how it's supposed to be used. It doesn't matter if it's monolights or speedlights or even ambient light...control comes from knowledge, not what equipment or modes you're using.



Jan 11, 2013 at 10:35 PM
jzucker
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p.2 #11 · Do I need a light meter?


Graystar wrote:
But the control over the lighting is definitely better.


No control over the lighting can be better than manual .

Anyway, i'm outta here. No need to reply.



Jan 11, 2013 at 10:52 PM
cgardner
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p.2 #12 · Do I need a light meter?


No exposure / flash output controlled by metering is perfect or foolproof. The metering can measure which zone on the viewfinder is the darkest and which is the lightest with certaintly but it's accuracy in doing so is limited by the number and size of the zones and how the scene content overlaps them.

Let's say you are taking a table photo at a wedding, asking the people nearest the camera to stand beside the people on the opposite side of the 10 person round table 8ft from the camera. You know you want all the faces 8ft away correctly exposed, but what does the metering see is closest to the camera (which should be the focal point a flash photo)? A big white table cloth. What happens in ETTL mode at FEC=0? The metering programed to avoid blowing highlights exposes the near side of the table perfectly and underexposes the faces.

What would happen if using manual flash? Knowing the subjects were 8ft from the flash you'd select the power / aperture that would correctly expose the faces. But what will happen to the white table cloth in the foreground? It will be a blown out distracting blob in the photo exposed for flash at 8ft.

The solution? Stand on a chair when taking the shot to crop the white table cloth out of the photo. What happens with the FEC=0 ETTL shot? It will react to the light reflecting off the people 8ft away because there's nothing in the foreground skewing the metering. What will happen in the manual flash shot? It will look the same buy not have the distracting background.

The lesson there? Flash, both manual and ETTL, requires composing it differently than in ambient light, consciously framing any flash shot so what needs to be correctly exposed in a direct flash shot is closest to the flash to avoid skewing ETTL metering or blowing foreground detail in manual exposures.

What you will find when you start composing that way is that ETTL does a much better job at getting exposure correct at FEC=0.

I used manual flashes with power and distance for years before getting my Canon ETTL flashes. It was ingrained instint to compose flash shot with the focal point needing correct exposure closest to avoid blown out foreground detail.

I also used Vivitar flashes in auto mode and knew it was necessary to adjust aperture based on scene content from and "average" baseline. If an average mix of reflections reached the meter the default f/stop would work. But if the scene was filled with a bride in a white dress the meter in the flash, seeing more light come back would shut off the flash sooner and underexpose the dress. Conversely if the scene was nearly all black the the metering in the flash would blow the small highlights trying to pump more flash power into the scene.

You need to be aware of the same cause and effect with ETTL flash. If shots are not composed with the focal point nearest to the flash (key flash in a dual flash configuration) FEC=0 will underexpose the focal point in an attempt to correctly expose the foreground. FEC can be adjusted to correctly expose the focal point, but as with manual flash that will overexpose the foreground.

As with the Vivitar auto mode huge differences in scene reflectivity will require FEC adjustment. When time allows I move FEC back to 0 for each new scene, take a shot, and see how the metering evaluated the scene. If my intended focal point is not correctly exposed in the highlights at FEC=0 it tells me something in the scene is skewing the metering assumptions; either a bright distraction like a specular reflection off a shiny object, lighter or darker than average overall scene content, etc. It's not a matter of the metering getting it "wrong" but rather the scene not matching what it was programmed to expect at the FEC=0 default baseline.

The need to constantly evaluate the results and adjust FEC to control highlight exposure is the trade-off for the convenience of being able to move around with two flashes, shooting one shot with directly aimed flash and the next by bouncing the light off the ceiling. With two flashes the ETTL metering will keep the A:B ratio consistent, you simply need to monitor the highlights in the playback and adjust FEC to keep them.

An A:B=1:2 fill:key ratio will not look the same in every location due to factors like spill off ceilings. But manually set ratios vary in the same way for the same reasons. That's why it's important to learn from experience and comparison of camera playback and computer appearance of the same files to judge lighting ratios visually on the playback. That requires consistent exposure of the highlights, which is why I expose per the clipping warning in white highlights, then adjust the ratio based on how the shadows appear in the playback. That's an entirely visual and creative subjective judgement, something setting a ratio by rote based on incident ratios doesn't give you.

Incident metering in a studio setting works consistently because the varible of spill fill is consistent session to session in that room. But if you metered a 3:1 H:S ratio with key one stop above fill in your studio and then repeated the same ratio metering at night outdoors or in a huge church with 50ft ceilings the same 3:1 ratio will produce different results outside and the church because there's no spill fill.

The visual feedback of digital photography is the same as shooting Polariod to verify how metering settings actually looked back in the film days due to those variables. If a photographer learns to interpret camera play back and corollate it to what the clipping warning and histogram are revealing about the fit of scene to sensor it is quite easy to shoot with flash in manual or ETTL mode without a hand held flash meter.




Jan 12, 2013 at 12:16 AM
Graystar
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p.2 #13 · Do I need a light meter?


jzucker wrote:
No control over the lighting can be better than manual .

That is a very limited view of lighting.





Jan 12, 2013 at 01:30 AM
jzucker
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p.2 #14 · Do I need a light meter?


Graystar wrote:
That is a very limited view of lighting.



No, you've got it backwards. The human brain controlling all aspects of the exposure manually and creatively can never be surpassed by automatic exposure calculation. It's pretty obvious, innit?



Jan 13, 2013 at 06:43 PM
Graystar
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p.2 #15 · Do I need a light meter?


jzucker wrote:
No, you've got it backwards. The human brain controlling all aspects of the exposure manually and creatively can never be surpassed by automatic exposure calculation. It's pretty obvious, innit?


I thought you were "outta here". Anyways, you obviously missed this...

"It doesn't matter if it's monolights or speedlights or even ambient light...control comes from knowledge, not what equipment or modes you're using."

Most likely you missed it because you're not reading anything I write.

Automation is a tool...not a goal.

We mock what we don't understand.
Austin Millbarge



Jan 13, 2013 at 07:08 PM
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