The Sunny f/16 Rule. Flash? Creativity?

[cyracles]

Hello everyone, quite a while. I hope you are all in good health. I have a question.

I have read about and tried the f/16 rule but what i want to ask is this: i have been advised severally even on this site that when shooting in sunlight or daylight, using flash helps lighten up the subject's face. With the f/16 rule that is supposed to give a fairly decent or correct exposure on sunny days, does it still make sense to use flash for the same purpose?

Secondly, since the f/16 rule stipulates a certain f-stop. Now there may be some times when you want for example, a subject with the background blurred...picture a footballer's acrobatics captured in mid air with a colourful but blurred array of spectators. Now how do you achieve this instance?


Thank you.

[William W]

. . . tried the f/16 rule but what i want to ask is this:

i have been advised severally even on this site that when shooting in sunlight or daylight, using flash helps lighten up the subject's face. With the f/16 rule that is supposed to give a fairly decent or correct exposure on sunny days, does it still make sense to use flash for the same purpose?

The F/16 Rule is for a Front Lit Sunlight Subject.
Flash as Fill in Daylight, is to soften the hard shadows.

BOTH can co-exist.
That is to say, Flash as Fill, CAN be used to soften the shadows of a Front Lit Sunlight Portrait.
If a Speedlight (i.e. an Hot Shoe Flash) one would use Direct Flash, slightly from the Shadow Side aimed at the shadow side of the Face.

***

Secondly, since the f/16 rule stipulates a certain f-stop. Now there may be some times when you want for example, a subject with the background blurred...picture a footballer's acrobatics captured in mid air with a colourful but blurred array of spectators. Now how do you achieve this instance?

The F/16 Rule does NOT stipulate a certain F/stop.
It stipulates a certain set of exposure parameters – F/16 @ 1/ISO @ ISO
Which translates (for ISO 200) as: F/16 @ 1/200s @ ISO200

NOW you can CHOOSE any set of exposure parameters to make your shot; for example these are only some of the choices you have:

F/16 @ 1/200s @ ISO200 ≡ F/11 @ 1/400s @ ISO200 ≡ F/8 @ 1/800s @ ISO200
≡ F/5.6 @ 1/1600s @ ISO200 ≡ F/4 @ 1/3200s @ ISO200 ≡ F/2.8 @ 1/3200s @ ISO 100
≡ F/2 @ 1/3200s @ ISO50


Would you give me the courtesy of writing out what is the F/16 Rule, please?
I think you might not have a proper comprehension of it.

WW

[GiacomoD]

Hello Ife,
I strongly suggest you to read The Better Photo Guide to Exposure by Sean Arbati, I found it extremely useful to understand not only the f/16 sunny rule but also, more important, how to reason when approaching the exposure issues using Manual settings.

About your questions:
1) yes, in some lighting situations it makes perfect sense: for example, if your foreground subject is partially or totally shadowed, you can use the f/16 rule to correctly expose the background and the flash (better if slightly reduced, about -1EV) to provide a decent illumination of your subject.

2) the f/16 is just the starting point of the rule, Then you can set your camera to any equivalent exposure. For example f/16-1/125, f/11-1/250, f/8-1/500 and f/5.6-1/1000 are all equivalent exposures, meaning that the total amount of light entering into the lens is the same, while the depth of field will vary according to the aperture used.

Hope it can help
Best
Giacomo

[cyracles]

Hello William, hello Giacomo. Thank you for you responses. I guess i was viewing it as a sure-bet formula. I think i have more to learn in that respect. Indoors, i have no troubles with manual settings and bouncing my flash off the ceiling but outdoors that is supposed to have more light becomes a huge problem. Problems like : how you tilt the flash head for daylight shots without blowing the picture. How much power is reduced...and so on.

I have Nissin 622mkii flash.


And William, please go ahead and write about what the f/16 rule is. Thank you.

[William W]

The most detailed explanation of the “F/16 Rule” I can give is:

The F/16 Rule states that for a Front Lit, Full Sunlight Subject, photographed between the Tropics of Capricorn and Cancer, between two hours after Sunrise and two hours before Sunset, the correct Exposure will be: F/16 @ 1/ISOs @ ISO

I have found this to be correct with ⅓Stop for mostly all situations; Winter and Summer – except for Snow and Hard White Sand Beach Locations.

***

Over the past several years, I have corresponded with another Specialist Wedding Photographer located in San Francisco – we both have had identical DSLR cameras and we both note that the F/16 Rule MINUS ⅓Stop Exposure (i.e. F/11 @ 1/250 @ ISO 100) is the most ‘correct’ for both our locations.

I am not versed enough in the physics to understand why, but my guess is the depletion of ozone.

However, located in Sydney (AUS), I stick to the F/16 Rule as written. I know that I can ‘overexpose’ by at least ½Stop with all of my DSLR Cameras and then ‘recover’ the highlights in Post Production.

My San Francisco colleague, however, takes a more conservative approach, but I note that she uses Flash as Fill in Direct Front Sunlight and that does (may) add one layer of exposure, equivalent to about ⅓Stop to the Sun Lit Side of the face.

If I am may link to another site – this is a practical example of the F/16 Rule.
These three photographs were made without reference to any exposure meter. (Double-click to open each image; then double click again on the image to view it in more detail.)

WW

[GiacomoD]

how you tilt the flash head for daylight shots without blowing the picture.

As far as I know, tilting the flash head works indoor because the flash light is reflected and diffused by the roof, providing a less harsh illumination of the subject.
I would never tilt the flash outdoors, unless some surface above it can provide the reflection/diffusion of light. Instead, decreasing the flash power can help in getting a more natural result. The amount of decrease can vary in different situations.

[cyracles]

Thanks. So Giacomo, what you mean is that the flash should be pointed facing the subject directly while one only needs to adjust the power accordingly?

[GiacomoD]

Yes, this is my opinion.

Anyway, I think that the best thing you can do is to go outside and shot a foreground subject both with tilted full flash and with straight, adjusted flash, then compare the results!
When decreasing the flash power, take into account also the distance of the subject from your camera: the more far it is, less decrease is needed.

[rpcrowe]

Ife wrote:

"what you mean is that the flash should be pointed facing the subject directly while one only needs to adjust the power accordingly?"

Although you can use direct unmodified flash for outdoor fill light; I like to use a diffuser/mini-softbox when shooting with direct flash fill outdoors. I believe that the original manufacturer of this type of item was Lumiquest.



The above shows the lumiquest on a bracket that I use for macro work. However the mini-softbox can also be used when you are shooting on-camera hotshoe flash for straight on fill.

The diffuser attaches to the flash using Velcro but, you could alternately secure it with an elastic band.

There are many Chinese copies of the Lumiquest Mini-Softbox which are available on eBay for very low prices. This is an example. They are pretty well able to be used on any model hotshoe flash.

http://www.ebay.com/itm/Pixco-Flash-...item33758f98d4

The build quality may be slightly less in the Chinese knock offs but, they are fine for diffusing straight-on fill flash and the price is certainly less expensive.

Regarding adjusting the power of on-camera fill flash, I usually start with the flash at - 1/2 EV. Usually, I start there and it will work most often; except that sometimes, when the light is particularly bright, I may not reduce my flash. Although this may sound counter-intuitive, it is because the shadows in harsh bright sun are deeper and need a heavier dose of fill..

BTW: A problem with this type of diffuser is that it physically blocks the auto-focus assist light so it is not great for shooting in lower light levels in which you make use of the auto focus assist.

Lumiquest offers a unit that is shaped so that the auto focus assist light is not blocked. Since I use my softbox for outdoor fill light, blocking the auto focus assist light is not a problem.

http://www.ebay.com/itm/Lumiquest-So...item1e77c93045

The new Lumiquest mini softboxes also have a gradient on the diffusing screen which is said to balance the light from the flashtube so that the center is not too hot. I don't have the gradient on my original model Lumiquest and I have not seen one on the Chinese knock-offs. However, for outdoor fill flash, I don't think that it is really necessary.

Shooting with of camera fill-flash is a different subject and a method of triggering the flash must be added to the equation...

[William W]

Indoors, i have no troubles with manual settings and bouncing my flash off the ceiling but outdoors that is supposed to have more light becomes a huge problem. Problems like : how you tilt the flash head for daylight shots without blowing the picture. How much power is reduced...and so on.

I did not see this other question when I posted my response to your request for details of the F/16 Rule.

“How do I use Flash as Fill Outdoors?”
This is NOT a simple question for which one answer will fit all situations.


So let me explain:

I am ONLY answering about how to use Flash Outdoors in the context of Flash as Fill AND the F/16 Rule AND using a typical ON CAMERA Hot-shoe Flash unit. **1

***

IF you are using the F/16 Rule for your exposure THEN, by DEFINITION:

1. You have a FRONT LIT FULL SUNLIGHT Subject OR
2. You are using the F/16 Rule for the correct exposure for other parts of the scene AND you want the Flash Fill Area to match that Sunlight Exposure of other parts of the scene

Let’s assume you want to make a Portrait.

Then these are my recommendations:

• IF you then wish to use Flash as FILL for the SUBJECT, it will be best to use DIRECT FLASH.
• You will ONLY be able to shoot at about 8ft to 10ft (maximum), from the Subject.
• IF the SUBJECT is in Direct Front Sunlight: then it will best to shoot in PORTRAIT Orientation, so you can get Flash Head pointing (a bit) toward the Shadow Side of the Face.

***

The Rationale for those recommendations:

The main two challenges to overcome when using Flash as Fill, in Direct Front Lit Sun are:

1. The restrictions of the Flash’s Working Distance (WD), caused low power - low Guide Number (GN)
2. The limitations Camera’s Maximum Sync Speed**2

***

Working Example:

For this following example we will be using a Nissin 622mkii Flash Unit.

The Specs (I found) say the Guide Number, (GN) for this particular Flash unit, are:
GN - ISO100 / meters (for 135 format camera):
GN25 at FL = 24mm; GN35 at FL = 50mm; GN44 at FL = 105mm.

We don’t know the OP’s Camera and lenses - I will use a Canon EOS 5D and the EF24 to 105/4 for the example.

Assume we use the lens at 50mm and we frame the portrait as a Long Half Shot (thighs to head with a bit of air above the head).

We will be about 9ft (3mtrs) from the Subject when we frame the shot in Portrait Orientation. So the Flash’s WD is 3mtrs (because it is mounted on the Camera’s Hot-shoe).

The camera’s Max Sync Speed is Tv = 1/200s (this is the FASTEST shutter speed useable, with Flash).

For the EXPOSURE, we use the F/16 rule – so let’s use this exposure:
F/11 @ 1/200s @ ISO100



Now let’s look at the Guide Number of the Flash unit.

The GN (at ISO100) and for a 50mm lens is: 35.

The formula is: GN = D x f
(GN = Guide Number; D = Distance; f = f/number of the aperture used)

So substituting in the Distance and the f/number for this particular shot, we get: 3 x 11 = 33.

So therefore we now know that using a flash with a GN = 35, we are right on the absolute limit of the Flash’s capacity to fill the shadows to match the Sunlight Exposure and this also assumes the manufactures have NOT been elastic with the truth about the GN.

This is why, in the particular circumstance about which OP is asking (Flash Fill in a Direct Full Sunlit scene) it is (usually) always necessary to use the Hot-shoe Flash as direct flash, for any Fill – because one cannot afford any reduction in Flash’s Power by bounce or diffusion.

Also, this is why some Flash Fill in Sunlight shots which are attempted; are indeed, just impossible to make.

WW


Footnotes:

**1
You could use an "Off Camera Cord" which will allow the FLASH to keep its working distance from the Subject and yet allow the camera to be farther away from the Subject.


**2
I purposely have not mentioned High Speed Sync. I don't believe the OP's Flash has that functionality. But if it does, then whilst using HSS will somewhat overcome the issue the Camera's Max Shutter Sync Speed, on the other hand, using HSS will reduce the effective power of the Flash and hence reduce the available Working Distance of it.

[cyracles]

Wow Bill! Thanks. The example with the Nissin flash really resonates with me as this is the exact type i own too. Now i'm getting there albeit gradually. Given an option between off camera cord(i believe that spiral cord[like telephone handset to phone box cord] and the wireless remote trigger, which one would you advise?

[bambleweeney]

I'd certainly go for wireless triggers for several reasons. No cords to trip over, get disconnected from flash or camera and additionally you'd need one with a reasonable length as you experiment getting the flash further off camera. I use Yungnuo triggers and find them 100% reliable, last time I looked they were about 40 Euros for receiver/transmitter although they have some newer models out now. The advantage obviously is no cords getting in the way but also if you use an external meter to balance flash and daylight you can meter directly from the subject and fire the flash remotely to get a reading. Another advantage is that you can use the same transmitter/receiver to remotely trigger your camera, handy for those self portraits or setting up a camera to take wildlife shots without being on scene to disturb the animals/birds etc.

[Nicola]

Very interesting thread here,
I'd like to contribute more, but I'm at office at the moment...
so I just quickly add that an other important aspect in matter of fill in flash outdoor is the light temperature: when shooting at sunset, for instance, a gel on the flash may be of help to avoid an un-natural look of the subject...

[cyracles]

Thanks for the additions Bill. Nicola, if one can not get a gel, how can one improvise?

[William W]

Wow . . .Thanks. The example with the Nissin flash really resonates with me as this is the exact type i own too. Now i'm getting there albeit gradually. Given an option between off camera cord(i believe that spiral cord[like telephone handset to phone box cord] and the wireless remote trigger, which one would you advise?

Neither.
I would advise you to get very experienced with using Flash as Fill in Full Sunlight with your Nissin and master that, before you buy or try anything else.

WW