Flash in Av or Tv mode

[jforget1]

Have been playing around with my 580EX which I have had limited opportunity to use and want to make sure when I need it I know all the functions.
When I am in P mode and have the flash in ETTL all works fine, but when I am in Av or Tv mode and have the flash in ETTL I cannot get it to give me a reading figuring the flash will fire. In Av it stayed around 1/6 of a second. What is the best way to get good flash exposures but also have some control over DOF.

Hope this question makes sense.
Joe

[AjP]

in AV,Tv, M modes it doesn't compensate for flash, these is manual modes,
if in Av or Tv shutter speed to slow, switch to M and set manual, you can check if your setting close by switching to P and see what would be reading.
I usually shoot 1/60-1/125

IMHO

[jforget1]

in AV,Tv, M modes it doesn't compensate for flash, these is manual modes,
if in Av or Tv shutter speed to slow, switch to M and set manual, you can check if your setting close by switching to P and see what would be reading.
I usually shoot 1/60-1/125

IMHO

Thanks for the help, I will give your advice a try.

[Jon]

There is a Custom Function (CF-3 on the 20D, CF-6 on the D60) that will "force" the camera to use flash sync speed in AV rather than metering for the available light and filling with the flash.

[jforget1]

There is a Custom Function (CF-3 on the 20D, CF-6 on the D60) that will "force" the camera to use flash sync speed in AV rather than metering for the available light and filling with the flash.

Gotcha, I was just looking through the custom functions and did not realize that is what that meant, I will try that setting.
Thanks

[robertwgross]

in AV,Tv, M modes it doesn't compensate for flash, these is manual modes,


Calling Av and Tv modes "manual" is kind of odd. M is manual.

---Bob Gross---

[Joe R]

Read the EOS Flash Bible:

http://photonotes.org/articles/eos-flash/

[jforget1]

Read the EOS Flash Bible:

http://photonotes.org/articles/eos-flash/

Looks like good information, I will give it a read, thanks.

[scottbergerphoto]

The camera meter never takes into account that you are using flash. It is for ambient light only. P mode is programmed not to go below 1/60 ever. You just tend to notice it more when using flash because you are usually in low light situations.

[Bosman]

The camera meter never takes into account that you are using flash. It is for ambient light only. P mode is programmed not to go below 1/60 ever. You just tend to notice it more when using flash because you are usually in low light situations.

Don't mean to "hyjack" this post, but.....
I have a G6 and 420ex, so is it better to use TV and set to say 1/125 indoors? The camera would probably give me an underexpose warning, but if it isn't taking into account the flash I should be ok. I hope this question makes sense, please forgive me if it doesn't and please correct me I'm still learning.

TIA

Joe

[Bosman]

The camera meter never takes into account that you are using flash. It is for ambient light only. P mode is programmed not to go below 1/60 ever. You just tend to notice it more when using flash because you are usually in low light situations.

On more thing, the camera never takes into account flash?
I thought the it "adjusted" the external flash based on lighting conditions?

[Jon]

The camer's exposure meter doesn't consider the flash when determining exposure. The flash level's set separately based on the pre-flash, using the mystical incantations "E-TTL" or "E-TTL II" (unless the flash is set to "Manual").

And yes, you're likely to be better off using Tv and a high-ish shutter speed with the flash if you want to stop all the action.

[scottbergerphoto]

1. Read what I said carefully. The camera meter you see in the viewfinder is a measurement of ambient light and is never affected by whether or not you have a flash on the camera. The flash output in ETTL/2 will be affected by the level of ambient lighting .

2. Setting your shutter speed at 1/125 will eliminate most of the ambient light in an indoor situation, leaving just the flash. It's a creative decision how much/little ambient light to capture. That decision will also affect the white balance of the shot. If you are going to combine ambient and flash light, do a custom WB or shoot the first shot with a white card. Always shoot raw.

3. The shutter doesn't stop action when flash is the primary light source, the flash does. In a long exposure with flash, you will get some blur from the little ambient light that is recorded.

[Bosman]

1. Read what I said carefully. The camera meter you see in the viewfinder is a measurement of ambient light and is never affected by whether or not you have a flash on the camera. The flash output in ETTL/2 will be affected by the level of ambient lighting .

2. Setting your shutter speed at 1/125 will eliminate most of the ambient light in an indoor situation, leaving just the flash. It's a creative decision how much/little ambient light to capture. That decision will also affect the white balance of the shot. If you are going to combine ambient and flash light, do a custom WB or shoot the first shot with a white card. Always shoot raw.

3. The shutter doesn't stop action when flash is the primary light source, the flash does. In a long exposure with flash, you will get some blur from the little ambient light that is recorded.

Thanks Scott,

I started reading what JoeR posted and I am reading it assuming it applies to the G6 also. I am really learning alot and starting to understand what has been happening taking pics with my flash. I read somewhere that the slowest shutter speed you should try and hand hold is 1/125, but this is saying 1/60 should be ok to not worry about camera shake.

[Bodog]

but this is saying 1/60 should be ok to not worry about camera shake.
Depends. See #3 in Scotts reply. If the aperture you are using is wide enough to expose your subject (or background) at 1/60 shutter speed, then you could have camera shake/subject motion blur. Ain't flash fun?? :D

[robertwgross]

Don't confuse minimum handholding speed for daylight versus minimum handholding speed for flash. Since the flash pop is of such extremely short duration, it is over and done and the shutter is poking around over a much longer duration.

---Bob Gross---

[jforget1]

OK i played around with the flash tonight and have a better handle on it now based on the tips above. I have one last question, what do most people use for a setting for Fill lighting, lets say for outdoor shade shots?
Also would I use a different compensation if it my 580Ex or the onboard flash for spur ofm the moment shots when I need some fill but can't get to my camera bag.

Any advice is appreciated.

[scottbergerphoto]

Traditional Flash Fill for outdoor shots is usually -1 to -1 and 2/3 FEC. Do a Google Search on Galen Rowel (now deceased) and read his article on this subject.

[jforget1]

Traditional Flash Fill for outdoor shots is usually -1 to -1 and 2/3 FEC. Do a Google Search on Galen Rowel (now deceased) and read his article on this subject.
Thanks I will take a look at the article.

[jforget1]

Traditional Flash Fill for outdoor shots is usually -1 to -1 and 2/3 FEC. Do a Google Search on Galen Rowel (now deceased) and read his article on this subject.

Which article are you referring to here, there are a lot of articles and the one I have read are not on this subject.

[tim]

Try "smart flash outdoors" here (http://www.mountainlight.com/articles.html) - not sure it's the right article but that page has many. Google is nice to me.

[scottbergerphoto]

Smart Flash is Addictive

by Galen Rowell

Outdoor Photographer, October 1996

It's been eight years since I got hooked on smart flash. I especially remember an afternoon party where every slide came out with a perfect balance of fill and natural light. My Nikon 8008 was set on program mode with an SB-24 flash set at the -1.7 compensation ratio that I use to get natural- looking fill in landscape photographs.

When I later tried such casual shooting with either flash-equipped point-and-shoot cameras or more sophisticated SLRs with pop-up flashes, I could get acceptable one-hour prints for family use, but not well-exposed slides for publication. What caught my fancy, however, was that an occasional frame would come out just right.

In the last year, I've experimented with point-and-shoots and light SLRs for my lightweight adventures. What started me in this direction was Nikon's introduction of the N70 with the first programmable built-in smart flash. I tried "top-down" tests with the "smart" N70 and then began "bottom-up" tests with an old favorite Olympus XA and a super-light Canon Rebel-X SLR.

If you want to set the camera on autopilot and not worry about computing for the flash, there's no substitute for smart flash. If you prefer to have finer control over the image, however, the odds of balanced fill-flash with an unsmart camera can be greatly increased.

Without a smart flash, the desired -1.7 compensation ratio can be attained in a number of ways. A dedicated flash unit that ties the amount of light to the film speed setting on the camera can be fooled into doing the right thing for the wrong reason. First, set shutter speed and aperture for a manual exposure of the naturally lit background. Second, set the exposure compensation for -1.7 stops (or 1.5 if no 1.7 setting). For cameras without this adjustment, set the film speed 1.7 stops higher than normal; for example, ISO 320 instead of 100. Now you'll have a correct background exposure combined with flash that won't blow out natural shadows with overly bright fill. Remember to set your film speed back to the original ISO or you might end up with whole rolls of seriously underexposed pictures.

Things get more complicated when built-in flash units are relatively weak or not dedicated. Beginning from square one, you need to determine at what distance and apertures your unit will give you perfect looking flash fill. Don't trust the listed guide number for your flash unit. Logically, it should be too low; you need 1.7 stops less light for fill than for full-power flash in totally dark situations. Practically, guide numbers tend to be exaggerated, unless, that is, you're shooting in a narrow white hallway in a Hobbit house with five foot ceilings, where lots of light is reflected. In the open outdoors, effective guide numbers are cut in about half.

The concept of a guide number is far more simple than its relationship to light falling off in inverse proportion to the square of the distance makes it sound. Because the f-stops on your lens are also based on squares relating to the size of the lens opening, a flash guide number for a particular film speed remains constant as simply aperture times distance. A guide number of 64 means that at f8 a subject can be properly lit up to eight feet; at f16, four feet.

When I tested a Nikon N70 for outdoor fill with ISO 100 film, I began by setting the lens at f8 using the pop-up flash at distances varying from 2 feet to 8 feet. Without flash exposure compensation, only one of these distances would give a correct exposure, but the N70 with its built-in smart flash gave perfect exposures up to five feet, where they began to go dark. I concluded that 4.5 feet was the maximum distance, and eight times 4.5, or 36, was my guide number. To confirm this, I later tested fill up to 18 feet at f2 and down to about 2 feet at f16. I get a majority of properly exposed fill-flash images with the N70 simply by checking to make sure that I'm always within the limits of my experimental guide number.

With the Canon Rebel-X, exposures aren't so simple. The extremely light camera is very appealing for recreational use, but it lacks a flash exposure compensation setting and has a fill guide number that tests out at 30. Images made closer than the distance computed with the guide number are consistently overexposed for natural-looking fill. I go the extra step and use the guide number to select my distance and f-stop for accurate fill.

If successful fill-flash in the outdoors was merely a matter of choosing guide numbers, lots of people would be doing it with simple cameras. There are other complications. The two photographs printed here were made with and without fill-flash using a Canon Rebel-X on a climb of El Capitan in Yosemite. Without flash, the image is too dark. With flash at five feet at f5.6, the fill is excellent except for a strange round shadow on the rock at the left. The 20-35mm zoom lens interferes with the built-in flash's coverage area at close range with wide-angle settings.

There are three easy corrections for this problem. One is never to shoot wider than 28mm. The camera's manual recommends this limit as the coverage of the flash, but in practice the fill looks okay on this 20mm shot, even with a bit of fall-off at top and bottom. The second solution to the lens-shadow problem is to turn the camera 180 degrees so that the shadowed flash is against the natural light of the sky. The alternative of using the 28mm setting and backing farther away from my subject was not an option on a tiny ledge a thousand feet up a sheer rock face.

A major problem with overexposed backgrounds happens when a camera with a low flash synch speed and a weak flash is used in an auto-exposure mode. An aperture of f8 that works perfectly for fill at four feet will give a hideous two-stop or more overexposed background in bright daylight if the camera automatically limits shutter speeds to 1/90 sec. when the flash is popped up. The Nikon N70 is better at 1/125 sec. More sophisticated top-of-the-line Nikons and Canon SLRs have a far more versatile 1/250th synch speed, but lack a built-in flash.

In summary, any camera with a flash can give you perfect daylight fill if you know how to choose the situation. Depending on whether your flash unit is basic, dedicated, or smart, you will need to follow some or all of these procedures:

1. Compute your own experimental guide number and stay within its limit of shutter speed times aperture.

2. Don't let your camera choose a slow flash synch speed that will overexpose the natural light. (Many cameras have warning signals for this.)

3. Test wide-angle or large-diameter lenses for light fall-off and shadowing on close subjects.

4. When shooting verticals, turn the camera so that the flash is on the side of the lens that maximizes light on the subject and minimizes shadowing of wide or large lenses.

When all is said and done, it takes a focused mind as well as camera to make consistently good fill-flash exposures, unless you're willing to carry around that pro SLR with a 1/250 sec. synch speed and separate flash that allows you to shoot away at f8 or f11 in bright daylight. I'm still waiting for someone to come out with a perfect camera for my outdoor adventures. It should weigh less than a pound, zoom to 20mm with full flash coverage and no lens shadow, synch to 1/500sec. and have programmable flash exposure compensation. Until then, I've learned how to make do.

[scottbergerphoto]

Not a double post. It just didn't register on the title page. :rolleyes:

[jforget1]

Thanks scott I will give this a read.

[jforget1]

Interesting stuff in the article, good info. One last thing I thought of today is for outdoor fill flash do you position the flash facing forward or do you put it vertical. Also, I have a Lumiquest diffuser and wonder if I should remove that for fill flash shots.

[scottbergerphoto]

Since there is nothing to bounce off of outside, usually you are shooting straight ahead with or without an Omnibounce, at 45 degrees with an index card or bounce card to throw light forward, or at 180 degrees with a Pocket Bounce or ProMax with the insert that prevents light from going vertical.

[jforget1]

I have the pro max, so I will try that along with the others to see what works the best in the situation.

[scottbergerphoto]

I have the pro max, so I will try that along with the others to see what works the best in the situation.
Sounds like a good plan. Seeing is believing.
http://www.pbase.com/scottbergerphoto/diffuser_test