How to Properly Use Flash During the Day Outside?

[chunter]

I used the flash taking some pictures outside during the day. I wanted to get rid of the shadows on the people. Unfortunately, I ended up overexposing everything.
How do you use the fill flash outside during the day? Or, should you not use the flash?
I just got a new lens. The tamron 17-50mm 2.8 for my T2i.

I've attached the picture that was overexposed. I had it set to Av and the exposure level is set right in the middle. It was set to f2.8.

I assume it is because the shutter speed was too fast for the flash? Is the built-in flash on the T2i fast enough for a photo shot at 2.8 in sunlight?

 

[pixmedic]

I have that tamron lens. love it. (for nikon though)
first, why are you set to f/2.8 outside, during the day, when you are using flash? was your shutter speed high enough to compensate? what was your ISO?
what were your camera settings? what flash are you using? do you have a diffuser for your flash?
its hard to say exactly what went wrong without knowing what equipment you used, and what your camera settings were.
faster shutter speeds let LESS light into the camera, so you get less exposure. slower shutter speeds let MORE light into the camera.
its possible your shutter speed was too slow. or that you had the ISO too high.
the built in flash CAN be used for fill flash during the day, but it is harder to control than a hot shoe flash.

outdoor flash isn't just for shadows, its also good for softening harsh sunlight during the brightest times of the day.





View attachment 48125

 

[chunter]

first, why are you set to f/2.8 outside, during the day, when you are using flash? was your shutter speed high enough to compensate? what was your ISO?
what were your camera settings? what flash are you using? do you have a diffuser for your flash?

I wanted to get a shallow depth of field.
I used the flash to try and get rid of harsh shadows.
I just looked at the details of the picture. The shutter was set to 1/200. Which is way too slow.
ISO was 100
I was using the built-in flash in Av mode on my t2i. No diffuser.

Is it possible to set the shutter higher than 1/200 when using the built-in flash on the T2i?

 

[cgipson1]

first, why are you set to f/2.8 outside, during the day, when you are using flash? was your shutter speed high enough to compensate? what was your ISO?
what were your camera settings? what flash are you using? do you have a diffuser for your flash?

I wanted to get a shallow depth of field.
I used the flash to try and get rid of harsh shadows.
I just looked at the details of the picture. The shutter was set to 1/200. Which is way too slow.
ISO was 100
I was using the built-in flash in Av mode on my t2i. No diffuser.

Is it possible to set the shutter higher than 1/200 when using the built-in flash on the T2i?

Manual - http://gdlp01.c-wss.com/gds/9/0300003169/01/eosrt2i-eos550d-im-en.pdf

High speed sync is mentioned on Page 192 , 193... but didn't see how to set it up. I think you have to have an external flash.. the pop-up may not do it. I did find this for you :



hopefully that will help!

 

[amolitor]

When you're using flash outdoors (or anywhere there's ambient light that you want to use) there are really TWO exposures going on:

- the ambient light exposure, which depends on shutter speed, aperture, and ISO
- the flash exposure, which depends on flash power, aperture and ISO -- but NOT shutter speed

In the sort of situation you're looking at, you typically want to expose for the ambient light more or less correctly. Maybe a bit underexposed, maybe as much a a stop underexposed. More than that and you're starting to get into the land of "dark backgrounds in daylight" which looks bit odd.

Then you need to make up that underexposure with the flash, but since you're only a little underexposed, you just need a little flash exposure. The flash might be underexposed by 1 stop, or 2, or even 3 stops. If your ambient light expsure is under by 1 stop and so is the flash, they'll add up to "correct" exposure, half flash half ambient. If the ambient is only 1/2 stop underexposed, you need to be nearly 2 stops underexposed on the flash, so you're Mostly Ambient, with a Little Bit of Flash.

Then you need to make sure that your shutter speed is slower than the flash sync speed, which makes the whole setup fairly complicated.

Much of this depends on how much metering your camera is capable for doing, and how tightly coupled it is with the flash.

The short answer is "try very low flash power"

 

[jwbryson1]

I had it set to Av and the exposure level is set right in the middle. It was set to f2.8.

Post the EXIF data so we can see what happened. If you were set to 2.8 in bright daylight you probably needed to shoot faster than 1/200 to properly expose. I am guessing when you originally exposed the image, the meter said it was okay, but when you fired the flash, the camera adjusted to your flash sync speed which was much lower than the correct exposure speed.

I assume it is because the shutter speed was too fast for the flash? Is the built-in flash on the T2i fast enough for a photo shot at 2.8 in sunlight?

No such thing. The flash is instantaneous and occurs way faster than your shutter speed. Your shutter speed controls ambient light, not flash exposure.

 

[cgipson1]

When you're using flash outdoors (or anywhere there's ambient light that you want to use) there are really TWO exposures going on:

- the ambient light exposure, which depends on shutter speed, aperture, and ISO
- the flash exposure, which depends on flash power, aperture and ISO -- but NOT shutter speed

In the sort of situation you're looking at, you typically want to expose for the ambient light more or less correctly. Maybe a bit underexposed, maybe as much a a stop underexposed. More than that and you're starting to get into the land of "dark backgrounds in daylight" which looks bit odd.

Then you need to make up that underexposure with the flash, but since you're only a little underexposed, you just need a little flash exposure. The flash might be underexposed by 1 stop, or 2, or even 3 stops. If your ambient light expsure is under by 1 stop and so is the flash, they'll add up to "correct" exposure, half flash half ambient. If the ambient is only 1/2 stop underexposed, you need to be nearly 2 stops underexposed on the flash, so you're Mostly Ambient, with a Little Bit of Flash.

Then you need to make sure that your shutter speed is slower than the flash sync speed, which makes the whole setup fairly complicated.

Much of this depends on how much metering your camera is capable for doing, and how tightly coupled it is with the flash.

The short answer is "try very low flash power"

at ISO 100 F2.8 outside on a sunny day, there is no way (other than an ND filter) to get a shutter speed in the normal sync speed range that will allow a good exposure (look at the background in his shot). So either you would close the aperture down (negating the desired shallow DOF) or you lower ISO.. already at 100 ... so you are stuck with needing a fast shutter speed (well outside of the normal flash sync speed)

So High Speed Sync is his best option if he wants to use flash for fill... and still get a proper metered exposure of the ambient light.

[PhotoME]
PhotoME version: 0.79R17 (Build 856)

[Overview]
URL: http://www.thephotoforum.com/forum/...rly-use-flash-during-day-outside-img_6304.jpg
File type: JPEG
File size: 133.9 KB
Creation date: 6/15/2013 07:42
Last modification: 6/20/2013 09:01
Make: Canon (Canon Global)
Camera: Canon EOS REBEL T2i
Lens: Tamron 17-50mm F2.8 Di LD Aspherical [IF] (A16)
Software: Firmware Version 1.0.9
Dimension: 800 x 534 px (0.4 MP, 3:2)
Focal length: 35 mm
Aperture: F2.8
Exposure time: 1/200" (-0.67 EV)
ISO speed rating: 100/21°
Program: Aperture-Priority AE (Manual)
Metering Mode: Evaluative
White Balance: Auto
Focus Mode: Multi-point AF
Noise Reduction: Off
Flash: Flash fired, compulsory flash mode

 

[cgipson1]

Post the EXIF data so we can see what happened.

Jeff, Exif is in the image! Do you have an Exif reader? Try PhotoME.. although there are a lot of good ones out there...

 

[IgsEMT]

Outdoors:
On the sunny day: (sunny16 - at ISO 100 1/100sec f/16 - You'll BLOW OUT the whole image at 2.8). Thus you'll need to first set you ambient expure correctly. If shooting at wider apertures outdoors (lots of light), look into ND filters.
Once you set the ambient expsure, add flash to it (preferably off camera) at about 1-2 stops UNDER the ambient... this gives you soft enough light to fill in the shaddows and yet natural looking image w/o "flash" look.

Good Luck

 

[cgipson1]

Outdoors:
On the sunny day: (sunny16 - at ISO 100 1/100sec f/16 - You'll BLOW OUT the whole image at 2.8). Thus you'll need to first set you ambient expure correctly. If shooting at wider apertures outdoors (lots of light), look into ND filters.
Once you set the ambient expsure, add flash to it (preferably off camera) at about 1-2 stops UNDER the ambient... this gives you soft enough light to fill in the shaddows and yet natural looking image w/o "flash" look.

Good Luck

You did see where he wanted shallow DOF?

 

[chunter]

Ok, I saw the video and read i the manual about flash sync.

I'm a little confused. I assume outside when I set the f stop to 2.8, the shutter was probably at like 1/2000 or 1/4000. Then when I turned on the flash, it went way down to 1/200 because that is as fast as the shutter will go with the flash turned on in Av mode.

Here's what I don't understand: why would the camera have a max speed on the shutter when flash is turned on? If the camera shoots the light, and the shutter opens and closes at 1/4000 of a second, what difference does it make how slow the flash is? So, if the flash can only fire at a max speed of 1/200 of a second, what difference does it make as long as the shutter opens and closes at 1/4000 of a second?

I'm having trouble understanding why the speed of the flash makes a difference in bright sunlight?
I understand it makes a difference in total darkness, where essentially the flash is basically the shutter speed.

 

[jwbryson1]

Post the EXIF data so we can see what happened.

Jeff, Exif is in the image! Do you have an Exif reader? Try PhotoME.. although there are a lot of good ones out there...

Just downloaded it. :mrgreen:

 

[amolitor]

A shutter on a DSLR doesn't open all the way for the faster speeds. Instead it uses a pair of shutter curtains separated by a slit, and pulls that slit across the frame. This typically takes something like 1/200th of a second, even for the highest shutter speeds, say 1/4000. The width of the slit ensures that each part of the frame is only exposed for 1/4000th of a second, though, even though the whole operation takes much longer.

The flash is, we can pretend, instantaneous. So, at 1/4000, you'll get one teeny little strip of flash exposure somewhere in the frame, wherever the slit happens to be when the flash goes off.

High Speed Sync is family of technologies that overcomes this by stretching the flash exposure out to that 1/200th of a second, so every strip gets about the same amount of light from the flash.

 

[TCampbell]

I used the flash taking some pictures outside during the day. I wanted to get rid of the shadows on the people. Unfortunately, I ended up overexposing everything.
How do you use the fill flash outside during the day? Or, should you not use the flash?
I just got a new lens. The tamron 17-50mm 2.8 for my T2i.

I've attached the picture that was overexposed. I had it set to Av and the exposure level is set right in the middle. It was set to f2.8.

I assume it is because the shutter speed was too fast for the flash? Is the built-in flash on the T2i fast enough for a photo shot at 2.8 in sunlight?

You ended up creating a "high key" image (which actually is a kind of artistic effect on it's own as long as you can see the critical details).

Your shot is over-exposed, but this had nothing to do with flash.

When you shoot outside with the shot lit by the sun, your exposure is predictable because the sun puts out a very consistent level of light. There's a baseline rule with a catchy-name to make it easy to remember called the "Sunny 16" rule.

The rule says this: If you are shooting in full sun, you can set the aperture to f/16 and set the shutter speed to the "inverse" of the ISO speed. So at ISO 100, the shutter speed would be 1/100th and this will create a correct exposure. It turns out you can also use any "equivalent" exposure. E.g. you can open the shutter up by a stop (so that'd be f/11) which collects twice as much light, but then set a shorter shutter exposure by a stop (1/200th) to compensate. You still get the same amount of light.

In YOUR photo, you used ISO 100 and f/2.8. At f/2.8 you have increased the amount of light gathered by the lens by 5 full stops. That means to balance the exposure, you'd need to change the shutter speed ALSO by five full stops (which would be 1/3200th). If indeed this was taken at 1/200th, then your shot is over-exposed by 4 full stops (making it 16 times brighter than it should be.)

At that point, the flash is basically irrelevant.



When using a flash, you have to remember that there's a shutter speed limit called the flash "sync" speed.

When a flash kicks out it's burst of light, the duration of that light is VERY short. It may only be a few thousandths of a second. But since the camera shutter is mechanical, the shutter can't actually move that fast. It takes time to fully open the shutter, followed by more time to fully close the shutter. On YOUR camera, it takes about 1/400th of a second for the shutter to fully OPEN, followed by another 1/400th of a second for the shutter to fully CLOSE. That's 2/400ths or 1/200th of a second for the entire process. If the flash fires when the shutter is partially open, the only the part of the sensor which is exposed will get the benefit of the flash. THAT is why there's a max speed for using flash (on your camera that speed is 1/200th.)

If you're now wondering how it's possible for a camera to take a photo at a fast shutter speed (say 1/2000th) when the shutter has a max speed of 1/200th, it's because there are actually TWO shutters on the camera (they refer to these as "curtains") and they "chase" each other. One begins opening, exposing just a slit and then the second curtain begins following it... exposing only a small gap which sweeps across the face of the sensor.

The flash can be put in "high speed sync" mode IF the flash supports this feature (not all flashes do.) In this mode, the flash pulses rapidly while the curtain shutter moves across exposing that slit. Each "slit" gets an equal pulse of flash ... it's all done by computer to be precise and the image looks great. BUT... there is a catch. Since the flash has to pulse many times and normally a flash needs time to recycle (re-charge the capacitors to get ready to fire again), each pulse has to be at a small fraction of the total power that the flash could normally provide if it were just flashing once. This really cuts down on how much power you get and how far away your flash can effectively work.




The answer to the question you really want to ask is: How do you take a photo during the day using a flash as a "fill" to reduce harsh shadows?

Easy:

1) Set the camera to exposure settings which will ensure the shutter isn't FASTER than that 1/200th speed (the max "flash sync" speed). E.g. use Tv and set it to 1/200th.
2) Set the "Flash Exposure Compensation" setting (this has an icon of a lightning bolt with a +/- next to it) to "-1". This tells the flash to deliberately fire at a power level which is 1 full stop weaker than it would normally use (each "full" stop is 1/2 the light if going weaker or double the light if going stronger.) I find that "-1" creates a fairly naturally look shot that wont "look" like flash, but will adequately weaken shadows. You do want some shadows -- no shadows means no 3-dimensional look to your shots and they end up looking "flat". You just want the shadows to be gentle... not harsh.

You can tweak the flash exposure compensation setting to taste... I usually work in the -2/3rds to -1 1/3rd ... and I start at -1.

You wanted a wider aperture for narrower depth of field. This gets just slightly trickier because if open the aperture you have to speed up the shutter and if you go faster than 1/200th of the shutter you have to enable "high speed sync" mode (and you also must have a flash which supports that mode). Then the flash has to operate at a fraction of full power so the subject needs to be close. You can cluster a gang of flashes all operating at high-speed sync mode to overcome that obstacle but you can see how complex this is getting.

OR

You can use a neutral density filter.

Your shot was over-exposed by 4 stops. If you used a circular polarizer, that will cut about 2 stops of light (technically these are variable but usually pretty close to 2 stops). You could then use either a 2-stop ND filter or a 3-stop ND filter (I prefer the 3 stop). These filters screw onto the threads at the front of your lens (which means you have to buy the filters with the correct diameter for your lens.) That'd give you a total of about 5 stops of light. NOW you can shoot at f/2.8, NOT have to deal with high-speed sync, set a shutter speed of 1/100th, and set the flash compensation to -1 and you should get a result you really like.

 

[cgipson1]

Maybe this will help you to understand.... Sync About It?or Thinking About Syncing | PixSylated | Syl Arena's Photography Blog on Light & Imagemaking

Normal flash.. 1 big flash... when the shutter is fully open (synced)

High Speed Sync flash.. lot of little flashes really close together... so that the fast shutter speed (which is never really fully open like the normal flash sync) gets a flash for each position it is at...

In the T2i manual on page 192... it shows the Custom Functions for flash sync. IF the Custom functions are set to 1 or 2, High speed sync won't work.


Also keep in mind.. SHUTTER SPEED controls ambient light Exposure... APERTURE controls flash exposure. You need a much faster shutter speed to get the proper AMBIENT light exposure on a bright sunny day. And just a tiny pop of flash to fill in shadows.