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Canon 6D in AV mode with Flash
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Jun 25, 2019 01:59:43   #
rosarioc62 Loc: Ft. Lauderdale, Florida
 
im having trouble with the following settings
AV mode, ISO - Auto, F/2.8 flash ETTL. i have set min. cap on SS as 125. shooting indoors. still SS dips below 125. in order to get correct exposure i need the camera to use ISO instead of dipping SS. how to do this please someone help me here. thanks

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Jun 25, 2019 06:22:50   #
crazydaddio Loc: Toronto Ontario Canada
 
Go full manual and control shutter speed and Aperature.The challenge will be when you have ISO set to Auto and ETTL, you have 2 things that are Auto when it comes to exposure.
...I am actually not sure how the camera and flash negotiate the settings for flash power and ISO.....upt the ISO or up the flash power.

I shoot mostly full manual to avoid these kind of things. Exception is when I am doing fast transitions backing out of a church shooting a wedding. Set min shutter speed (so it never drops below a level where motion blur could start) and let the SS and ISO float with a set Aperature.

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Jun 25, 2019 07:03:30   #
rosarioc62 Loc: Ft. Lauderdale, Florida
 
crazydaddio wrote:
Go full manual and control shutter speed and Aperature.The challenge will be when you have ISO set to Auto and ETTL, you have 2 things that are Auto when it comes to exposure.
...I am actually not sure how the camera and flash negotiate the settings for flash power and ISO.....upt the ISO or up the flash power.

I shoot mostly full manual to avoid these kind of things. Exception is when I am doing fast transitions backing out of a church shooting a wedding. Set min shutter speed (so it never drops below a level where motion blur could start) and let the SS and ISO float with a set Aperature.
Go full manual and control shutter speed and Apera... (show quote)


sir i have set min. ss but it still dips below that on a 6D.

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Jun 25, 2019 07:20:07   #
BebuLamar
 
I don't know about the Canon as I don't have one. Is it possible because you enable slow sync? Besides when you use flash at f/2.8 unless the subject is quite far away (more than 15ft) you should be able to shoot at 1/250 and ISO 100.

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Jun 25, 2019 09:52:41   #
BebuLamar
 
Is your ISO fixed at 400 although you set it for Auto ISO?

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Jun 25, 2019 09:53:19   #
CHG_CANON Loc: the Windy City
 
Chapter 6 starting on page 169 of your EOS 6D manual covers all things under subject = Flash Photography. Check the shutterspeed settings on page 173 and consider whether these settings can override a minimum shutterspeed limit set elsewhere for the camera. You might consider too using Manual Exposure or a fixed ISO in Aperture priority to take more control of the exposure parameters vs what you've deferred to the camera's control.

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Jun 25, 2019 16:59:23   #
rosarioc62 Loc: Ft. Lauderdale, Florida
 
BebuLamar wrote:
Is your ISO fixed at 400 although you set it for Auto ISO?


yes at 400 only once flash is hooked up

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Jun 26, 2019 10:35:17   #
jeep_daddy Loc: Prescott AZ
 
crazydaddio wrote:
Go full manual and control shutter speed and Aperature.The challenge will be when you have ISO set to Auto and ETTL, you have 2 things that are Auto when it comes to exposure.
...I am actually not sure how the camera and flash negotiate the settings for flash power and ISO.....upt the ISO or up the flash power.

I shoot mostly full manual to avoid these kind of things. Exception is when I am doing fast transitions backing out of a church shooting a wedding. Set min shutter speed (so it never drops below a level where motion blur could start) and let the SS and ISO float with a set Aperature.
Go full manual and control shutter speed and Apera... (show quote)


Yes, Crazy is on the right track here. You must not use Auto ISO. You can use AV mode and select your aperture value, so that you have the proper DOF, but your shutter will vary then. Put the camera in ISO 400 and the speedlite in ETTL and try again.

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Jun 26, 2019 10:45:37   #
BebuLamar
 
rosarioc62 wrote:
yes at 400 only once flash is hooked up


In auto ISO and when the camera detects there is the flash on it fixes the ISO to 400. So no Auto ISO with flash.

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Jun 26, 2019 10:58:27   #
amfoto1 Loc: San Jose, Calif. USA
 
rosarioc62 wrote:
im having trouble with the following settings
AV mode, ISO - Auto, F/2.8 flash ETTL. i have set min. cap on SS as 125. shooting indoors. still SS dips below 125. in order to get correct exposure i need the camera to use ISO instead of dipping SS. how to do this please someone help me here. thanks


Get out of Av auto exposure mode.

Set the camera to Manual exposure mode. If you want to leave Auto ISO on, okay... but I wouldn't. Here's why:

Av is an auto exposure mode.

Auto ISO (with M, without ETTL flash) is an auto exposure mode.

ETTL flash (with M, without Auto ISO) is an auto exposure mode.

So you've set up an "auto-auto-auto" exposure mode. Is it any surprise that weird stuff is happening? The camera is trying to use three different AE modes at the same time!

Further, ETTL flash with any auto exposure mode automatically is set as "FILL flash", firing at reduced power. Usually the flash output is reduced by about 1-2/3 stops. You can override the reduction by dialing up Flash Exposure Compensation (FEC). But that's sort of hit-and-miss.

ETTL flash only fires as "FULL flash" when the camera is set to Manual mode (without Auto ISO!). ETTL flash and Manual camera mode is still an auto exposure mode though, because the camera's metering system is measuring the flash (it uses a 1/64 power "pre-flash") and controls how much light the flash will put out. You also can increase or decrease FULL flash using FEC.

ETTL flash with the camera in Manual with Auto ISO is "auto-auto"... It's two different AE modes. While probably not as unpredictable as "triple auto", it still might do weird, unexpected stuff. I have no idea, because I'd never use more than one AE mode at a time.

BebuLamar wrote:
In auto ISO and when the camera detects there is the flash on it fixes the ISO to 400. So no Auto ISO with flash.


I didn't know that! (As I said, I've never used Auto ISO with ETTL flash.)

This is even more reason to simply turn off Auto ISO when using ETTL flash (either FILL or FULL), if leaving it on forces you to use ISO 400. That's a limiting factor and may not be the ISO you wanted.

To recap:

1. Pick whether you want ETTL "FULL" flash or ETTL "FULL flash". If you want FILL, set the camera to Av, Tv or P auto exposure mode. If you want FULL, set the camera to M exposure mode, but be aware it's still "AE".

2. Don't combine AE modes unnecessarily. That can cause unexpected actions, such as you've seen. Besides Av, Tv, and P.... M with Auto ISO and M with ETTL flash are also both AE modes.

3. I can't see any situation where it would make sense or be useful to use Auto ISO with ETTL flash (especially in light of the above).

Finally, with FULL flash you control exposure primarily with lens aperture and the camera's ISO settings. Up to the camera's flash sync speed (1/180?), shutter speed doesn't matter much, although you can use it to control the "mix" of ambient light with the flash. A fast shutter speed and/or lower ISO setting can be used to make a background go dark, by recording less ambient light. Conversely, slower shutter speed and/or higher ISO can increase background appearance in an image. Regardless how the camera is set, the short duration of FULL flash actually acts like a shutter speed, typically about 1/720.

If using a shutter speed above the camera's flash sync speed, you have to use the flash's High Speed Sync (HSS) feature... This significantly reduces the duration of each flash and, in turn, the distance the flash will reach.

If using slow shutter speeds and flash with moving subjects, such that there will be a mix of ambient and flash light, use the flash's Rear Curtain Sync feature.... this makes "light trails" appear more normally, behind the subject. If Rear Curtain Sync isn't used, the light trails will make a moving subject appear to be moving backward!

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Jun 26, 2019 11:27:09   #
BebuLamar
 
amfoto1 wrote:
I didn't know that! As I said, I'd never use Auto ISO with ETTL flash. This is even more reason to simply turn off Auto ISO when using ETTL flash (either FILL or FULL). If leaving it on forces you to use ISO 400, that's a limiting factor and may not be the ISO you want.

To recap:

1. Pick whether you want ETTL "FULL" flash or ETTL "FULL flash". If you want FILL, set the camera to Av, Tv or P AE exposure mode. If you want FULL, set the camera to M exposure mode, but be aware it's still "AE".

2. Don't combine AE modes unnecessarily. That can cause unexpected actions, such as you've seen. Besides Av, Tv, and P.... M with Auto ISO and M with ETTL flash are also both AE modes.

Finally, with FULL flash you control exposure primarily with lens aperture and the camera's ISO settings. Up to the camera's flash sync speed (1/180?), shutter speed doesn't matter much, although you can use it to control the "mix" of ambient light with the flash. Regardless how the camera is set, the short duration of FULL flash actually acts like a shutter speed, typically about 1/720.

If using a shutter speed above the camera's flash sync speed, you have to use the flash's High Speed Sync (HSS) feature... which significantly reduces the duration of each flash and, in turn, the distance the flash will reach.

If using slow shutter speeds and flash with moving subjects, such that there will be a mix of ambient and flash light, use the flash's Rear Curtain Sync feature.... this makes "light trails" appear more normally, behind the subject. If Rear Curtain Sync isn't used, the light trails will make a moving subject appear to be moving backward!
I didn't know that! As I said, I'd never use Auto ... (show quote)


When using flash I always have the camera on full manual that is in M and auto ISO off. However, since the OP asked the question I download the manual to find out.

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Jun 26, 2019 12:45:00   #
amfoto1 Loc: San Jose, Calif. USA
 
amfoto1 wrote:
...1. Pick whether you want ETTL "FULL" flash or ETTL "FULL flash". If you want FILL, set the camera to Av, Tv or P auto exposure mode. If you want FULL, set the camera to M exposure mode, but be aware it's still "AE"....


Damn typo!

I meant:

1. Pick whether you want ETTL "FILL" flash or ETTL "FULL flash".....yada, yada.

BebuLamar wrote:
When using flash I always have the camera on full manual that is in M and auto ISO off. However, since the OP asked the question I download the manual to find out.


Frequently shooting sports, I don't use flash a whole lot.

But when I do, usually it's FILL flash... i.e., ETTL flash with one of the AE exposure modes (Av or Tv).... outdoors, strong mid-day sunlight, when shadows get heavy and can be a problem.

Flash slows down shooting though, as well as severely limiting bursts of shots in continuous mode... so often can't be used when shooting sports.

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Jun 26, 2019 13:48:57   #
BebuLamar
 
Actually to answer the OP fully here is the answer.
In Av mode there are 3 choices for the shutter speed when using flash.
AUTO: The shutter speed will vary automatically from 1/180 to 30 seconds depending on the ambient light.
1/180-1/60 SEC. AUTO: The shutter speed will vary from 1/180 to 1/60 depending on the ambient light but not slower than 1/60.
1/180 fixed: It's fixed at 1/180.

When Auto ISO is enabled and using flash the ISO is fixed at 400 and will not increase with ambient light.

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Jun 26, 2019 17:50:30   #
crazydaddio Loc: Toronto Ontario Canada
 
rosarioc62 wrote:
sir i have set min. ss but it still dips below that on a 6D.


Hmm. I will look into that...

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Jun 30, 2019 00:08:06   #
rosarioc62 Loc: Ft. Lauderdale, Florida
 
crazydaddio wrote:
Hmm. I will look into that...


thanks

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