Best creative mode (other than M) for E-TTL flash photography

[SumanV]

Hi,

I am a beginner in flash photography and I have recently bought an EOS RP. I have a flash (Godox TT 685C) and I am experimenting with it. I would like to know which creative modes (Av/Tv/P/Fv) is the best to use for flash photography with E-TTL? Will these be different say if one uses flash in different ways i.e. fill vs non-fill? Also, some years back when I was using flash in E-TTL with a EOS T2i/550D, I was getting darker results with flash in a particular mode (I don't remember which one it was). When I changed the mode then the images came out brighter. Is it that that mode prioritized for ambient light and then added flash?

I apologize if the question has been asked before. I will be grateful for help/advice.

Thanks and Regards
Suman

 

[Valvebounce]

Hi Suman.
I‘m no expert and I’m not familiar with the Fv setting, but I have used flash quite a lot. I mostly use M on flash and camera, gives total control. I believe that Av is the most limited, and Tv is basically the same as M with one part of the exposure triangle automated.
The best thing I can recommend is that you read Strobist lighting 101. This is a link to the page with the download, you can just read it on line too, as well as Strobist 102 and 103!
There are loads of other resources online too, for which I’m sure you will recommendations.

Cheers, Graham.

 

[SumanV]

Hi Suman.
I‘m no expert and I’m not familiar with the Fv setting, but I have used flash quite a lot. I mostly use M on flash and camera, gives total control. I believe that Av is the most limited, and Tv is basically the same as M with one part of the exposure triangle automated.
The best thing I can recommend is that you read Strobist lighting 101. This is a link to the page with the download, you can just read it on line too, as well as Strobist 102 and 103!
There are loads of other resources online too, for which I’m sure you will recommendations.

Cheers, Graham.

Hi Graham,

Thank you very much for the reply and for the link to Strobist lighting. I have seen the site but have not followed it completely. M gives the most control but for people shooting events which other creative mode would they choose?

Thanks and regards
Suman

 

[Valvebounce]

Hi Suman.
ETTL is very versatile and will within reason expose a shot correctly, the real decision for Tv or Av comes down to what, where and why you are shooting a subject
Shutter speed has little impact on the light from the flash that hits the sensor until you get in to high speed sync, above 1/200th or 1/250th depending on the camera due to the short duration of the light emitted from a flash.
Aperture size really affects the flash light hitting the sensor just the same as ambient light, however some bodies have settings to limit the shutter speed available when a flash is detected.
If you are wanting to shoot birds with flash, go manual, they react to the ETTL pre-flash and are either missing from the shot or in some bizarre non photogenic pose. Having said that there are some at the local hide that are so used to flash that they rarely even look up!

For example this is from my 7DII manual,
“To prevent a slow shutter speed, under [z1: Flash control], set [Flash sync. speed in Av mode] to [1/250-1/60 sec. auto] or [1/250 sec. (fixed)]”

This is to prevent the camera dropping down to shutter speeds below hand holdable speeds to expose the background correctly. Imagine trying to hand hold a camera for 30seconds for the background exposure!

Cheers, Graham.

 

[SumanV]

Hi Suman.
ETTL is very versatile and will within reason expose a shot correctly, the real decision for Tv or Av comes down to what, where and why you are shooting a subject
Shutter speed has little impact on the light from the flash that hits the sensor until you get in to high speed sync, above 1/200th or 1/250th depending on the camera due to the short duration of the light emitted from a flash.
Aperture size really affects the flash light hitting the sensor just the same as ambient light, however some bodies have settings to limit the shutter speed available when a flash is detected.
If you are wanting to shoot birds with flash, go manual, they react to the ETTL pre-flash and are either missing from the shot or in some bizarre non photogenic pose. Having said that there are some at the local hide that are so used to flash that they rarely even look up!

For example this is from my 7DII manual,
“To prevent a slow shutter speed, under [z1: Flash control], set [Flash sync. speed in Av mode] to [1/250-1/60 sec. auto] or [1/250 sec. (fixed)]”

This is to prevent the camera dropping down to shutter speeds below hand holdable speeds to expose the background correctly. Imagine trying to hand hold a camera for 30seconds for the background exposure!

Cheers, Graham.

Hi Graham,

Thanks again for the reply and a great tip regarding shooting birds with flash! I now understand that shutter speed doesn't affect the exposure from flash; it affects ambient light. I learnt about it before but … I forgot. I wondered how events (weddings etc.) are shot using flash as one doesn't have enough time to calculate exposure via M mode? This was the primary reason for my question. Would one still use M mode even in a fast paced situation? Also, can one calculate camera settings such that all elements of the photo (ambient light, colour) are satisfactory without trial and error i.e. without shooting trial photos?

Best regards
Suman

 

[Valvebounce]

Hi Suman.
Having only done the odd friends and family wedding (to use your example) I am not really the best one to answer that, but I think most pro photographers probably shoot manual and have learned to react quickly to changing light, they do it all the time so probably can visualise required changes and muscle memory combined with the viewfinder meter enables them to dial in changes quickly, plus ETTL will adjust accordingly.
I'm guessing that it is normal for a wedding photographer to use ETTL as I have watched a few at weddings and not noticed them making changes to flashes, with the possible exception of perhaps dialing in a bit of + or - value on the flash power which can be done via the top buttons and wheels whilst looking through the viewfinder on many (all?) cameras.

Cheers, Graham.

 

[old-pr-pix]

TBH, shooting indoor events I frequently use P or Tv mode. P mode is easy and I'm lazy. Tv lets me tweak how much background exposure I allow mostly relying on past experience to know what shutter speed to use. M is best when you have time to fine tune things but can be problematic otherwise - leave M for staged shots. Per Graham's comment, if you plan to use Av make sure you set the shutter speed range - I use the 1/250 - 1/60 setting. Otherwise you can get surprised by the camera exposing for the background and blowing out the foreground that is lit by the flash. Plus, multi-second hand held exposures just equal blurry pix unless you have excellent IBIS. (I can usually go down to 5 sec. + with my Olympus gear - I look forward to Canon providing similar capability.)

 

[snegri45]

Events.
Situation 1: Steady ambient light. Take a test shot, P, ISO Auto. Then switch to Manual, use results from test shot, adjust as needed, go for -1 ambient exposure, let the flash do its own thing at E-TTL II.

Situation 2: Ambient all over the place. Go with P, ISO Auto, E-TTL II. You may still want ambient at -1.

Obviously 1 is preferable, it typically yields great exposures that need little post production work. Case 2 gets iffier, but you will typically get workable images most of the time. More PP, though.

 

[SumanV]

@Valvebounce Thanks again Graham. I understand that experienced photographers use Manual mode with flash due to their experience.

@old-pr-pix Thank you for the reply and the suggestion to limit shutter speed when using Av mode. A year back, I think I used Av+Flash for my T2i and the image that came out looked as if flash didn't even fire. I read some explanation somewhere for this but I don't remember now.

@snegri45 Thank you for the tips and great photos by the way. When I used flash recently my exposures came out okay but the color was overwhelmed from flash. How do I preserve the ambient light color in the flash shot and achieve good exposure?

 

[privatebydesign]

E-TTL is proprietary and 'intelligent' it depends on what it thinks is going on in the way it reacts, it also tries to work out what it believes is the subject and will try to optimally expose only that.

So what does that mean? Well nobody knows exactly how E-TTL works (we know the order in which things happen, we don't know the actual calculations that are going on in the background or the algorithm it is following) or at what light levels it decides to become a fill flash, yes it will automatically ramp the power up and down depending on the scene EV.

Canon E-TTL flash metering is very clever because it actually works out two independent exposures, the ambient exposure that it will adjust shutter speed to expose, and subject exposure that it will adjust flash power to expose for. That means to unleash the true potential of E-TTL you cannot use Tv, you must use another mode, the best for control is Av, using Tv severely limits the ability of the system to work as intended. Obviously M mode gives the user most control but I generally use Av and keep an eye on shutter speed to make sure it isn't becoming too slow for the intended use.

 

[SumanV]

E-TTL is proprietary and 'intelligent' it depends on what it thinks is going on in the way it reacts, it also tries to work out what it believes is the subject and will try to optimally expose only that.

So what does that mean? Well nobody knows exactly how E-TTL works (we know the order in which things happen, we don't know the actual calculations that are going on in the background or the algorithm it is following) or at what light levels it decides to become a fill flash, yes it will automatically ramp the power up and down depending on the scene EV.

Canon E-TTL flash metering is very clever because it actually works out two independent exposures, the ambient exposure that it will adjust shutter speed to expose, and subject exposure that it will adjust flash power to expose for. That means to unleash the true potential of E-TTL you cannot use Tv, you must use another mode, the best for control is Av, using Tv severely limits the ability of the system to work as intended. Obviously M mode gives the user most control but I generally use Av and keep an eye on shutter speed to make sure it isn't becoming too slow for the intended use.

Thank you very much for the explanation @privatebydesign. I am starting to understand the effects of various modes using flash.

Best regards
Suman

 

[privatebydesign]

Thank you very much for the explanation @privatebydesign. I am starting to understand the effects of various modes using flash.

Best regards
Suman

NK Guy was the person who documented the way E-TTL II works best but that was way back in 2001-2006. the site can still be retrieved via webarchive http://photonotes.org/articles/eos-flash/index2.html but below I have copied and pasted the most pertinent part. There are a lot more flash models now and a lot of his articles are not very relevant anymore as they include the older E-TTL and the even earlier A-TTL.

Hope this helps.

EOS flash photography confusion.

The main area of confusion in EOS flash photography is the fact that P, Tv, Av and M modes handle flash illumination differently, especially when ambient light levels are not bright. Here’s a summary of how the modes basically work when you have a flash unit turned on. This summary assumes that you do not have FP mode flash enabled if that option is available to your particular camera and flash unit combination.

Mode	Shutter speed	Lens aperture
P	Automatically set from 1/60 sec to the camera’s maximum X-sync speed.	Automatically set according to the camera’s built-in program.
Tv	You can set any shutter speed between 30 seconds and the camera’s maximum X-sync speed.	Automatically set to match the shutter speed you have set.
Av	Automatically set between 30 seconds and the camera’s maximum X-sync speed to match the lens aperture you have set.	You can set any lens aperture you like.
M	You can set any shutter speed between 30 seconds and the camera’s maximum X-sync speed.	You can set any lens aperture you like.

And here are the details:

Program (P) mode flash.

The overriding principle of Program (P) mode in flash photography is that the camera tries to set a high shutter speed so that you can hold your camera by hand and not rely on a tripod. If that means the background is dark, so be it.
Program mode operates in one of two modes, depending on the ambient (existing) light levels.
1) If ambient light levels are fairly bright (above 13 EV) then P mode assumes you want to fill-flash your foreground subject. It meters for ambient light and uses flash, usually at a low-power setting, to fill in the foreground.
2) If ambient light levels are not bright (below 10 EV) then P mode assumes that you want to illuminate the foreground subject with the flash. It sets a shutter speed between 1/60 sec and the fastest X-sync speed (see above) your camera can attain. The aperture is determined by the camera’s built-in program.
Because the camera tries to keep the shutter speed at a reasonable speed for handholding the camera you will end up with dark or black backgrounds if you take a flash photo in P mode when ambient light levels are not bright.
On most if not all EOS cameras, P mode is not shiftable when flash (internal or shoe-mounted Speedlite) is used. Note also that DEP mode cannot work correctly with flash - its metering settings basically revert to P mode if you try it.

Tv (shutter priority) mode flash.

In this mode the camera lets you change the shutter speed. It then automatically chooses an aperture setting to expose the background correctly. Flash duration (flash output) is determined by the flash metering system. In other words, the camera always works in fill flash mode when it’s in Tv mode - it always tries to expose the background adequately, unlike P mode.
If the maximum aperture value of your lens starts flashing in the viewfinder it means the background of the scene you’re shooting is too dimly lit. If you want to try and expose the background then you should decrease the shutter speed to compensate. Otherwise the camera will just try and expose the foreground with flash and the background will come out dark. Naturally at slower shutter speeds you’ll need to use a tripod to avoid blurring caused by camera shake.
As always, the camera will prevent you from exceeding its built in X-sync speed unless FP mode is available to you and engaged. If the minimum aperture value of your lens starts flashing then your scene is too brightly lit. You must then either engage FP mode if it’s available or perhaps put a neutral density filter on the camera or use slower film. Or turn off flash altogether and simply use a reflector of some type to bounce ambient light onto the subject.

Av (aperture priority) mode flash.

Av mode lets you set the depth of field by specifying the lens aperture. The camera then chooses a shutter speed ranging from 30 seconds to the camera’s X-sync speed, in order to expose the background correctly. If that means the shutter speed is some really low value so that you need to use a tripod to avoid camera-shake blur, so be it. In dark conditions, therefore, Av mode works in slow sync mode.
Flash duration (flash output) is determined by the flash metering system. Like Tv mode the camera always works in fill flash mode when in Av mode.
There is one exception to this. A number of EOS cameras have a custom function you can set to ensure that the shutter speed in Av mode when using flash is locked to the X-sync speed. The EOS 10/10s and Elan II/EOS 50, for example, have such a custom function, which lets your camera behave more like P mode when in Av mode. However this custom function will only lock the camera to X-sync in Av mode and will not choose a shutter speed from 1/60 sec to X-sync, the way P mode does.
As always, the camera will prevent you from exceeding its built in X-sync speed unless FP mode is available to you and engaged. If the shutter speed value of 30" flashes in the viewfinder then there isn’t enough light to expose the background correctly and you’ll need a larger aperture or faster film. If the camera’s X-sync flashes in the viewfinder then you’ll need to decrease the lens aperture, engage FP mode if it’s available or use slower film.

Manual (M) exposure mode flash.

In manual exposure mode you specify both the aperture and shutter speed, and your exposure settings will determine how the background (ambient lighting) is exposed. The subject, however, can still be illuminated by the automatic flash metering system since the flash can automatically calculate flash output levels for you. This is a marked contrast to the olden days, when photographers would carry around little flash exposure tables with them in order to work out manual flash settings.
This is how flash works in manual mode. Note that we’re talking about the manual exposure mode setting only, which can use automatic TTL flash metering (it will not use A-TTL metering in manual exposure mode). Also, we aren’t talking about setting the output of the flash manually - that’s manual flash and a different topic altogether.

• Set your camera to M for manual exposure mode.
• Set the aperture and shutter speed to expose the background correctly.
• Press the shutter button down halfway if your flash has a rear-panel LCD (liquid crystal display). The flash coupling range will appear in the flash unit’s LCD. This range is the distance that can safely be covered by the flash.
• If your lens has a distance scale you can check the current focussing distance to ensure that the distance to your subject falls within this range. Otherwise you’ll have to estimate.
• If the “flash ready” lightning bolt symbol appears in the viewfinder you can press the shutter all the way to take the photo. The flash’s TTL or E-TTL system will determine the flash exposure level of the subject.

If your flash lacks a rear-panel LCD you won’t have a preview of the flash coupling range, of course. Also, LCD-equipped flash units will not calculate the flash coupling range if you’re using bounce flash, and the coupling range will not necessarily be correct if you have a diffuser on the flash head.
Some Speedlite flashes, such as the 540EZ and 580EX, can display the coupling range in either feet or metres, depending on which measurement system has been set by the small switch in the battery compartment. Others, such as the 430EZ, are hardwired to one measurement system or the other, depending on where the flash was sold. US market flashes used feet and all other countries on the planet* had only metre flashes available to them.
* Trivia note - even countries such as Canada and the UK which are officially metric but which are nonetheless full of people who still use imperial measurements. Also Yemen, Rwanda, Burundi and Burma, which used to stand proudly with the USA as the planet’s only officially non-metric countries and which have now given up and are switching over to metric. Liberia is the only holdout I can find, and even there it’s only the government - apparently businesses and schools use metric.

 

[privatebydesign]

E-TTL flash metering patterns:

The camera uses its evaluative metering system to meter the flash output, based upon the preflash. When in autofocus mode most EOS bodies which do not use E-TTL II bias flash metering toward the currently selected AF point, but always in an evaluative mode pattern - they don’t use spot or partial metering patterns. When in manual focus mode it appears that at least some EOS bodies switch to centre-weighted averaging.

Note, however, that this biasing of E-TTL metering to the active point is potentially problematic, since it means that the flash metering is done in almost a spot-metering fashion. Many user complaints regarding flash metering problems in E-TTL mode appear to be linked to this issue. If the camera happens to be over a dark object, for example, flash metering can be considerably overexposed, and vice-versa. The standard answer to this problem is to use FEL and meter off something mid-toned, but this is clearly not a solution for rapid-shooting situations such as weddings and sports. Another approach is to set the camera lens to manual focus, since the body apparently switches to centre-weighted average metering in that mode, but that’s obviously not a useful answer much of the time either.

Users of the digital D30 and D60 have been particularly unhappy with E-TTL flash metering. The 10D apparently reduces this problem by defaulting to a centre-weighted averaging metering pattern in E-TTL, even when the lens is set to autofocus.

E-TTL II addresses this problem by altering flash metering considerably. It examines each evaluative metering zone before and after the E-TTL preflash. It then calculates the weighting for each zone independently, biasing against those zones with high reflectivity in the preflash. This means that E-TTL II does not have a flash metering pattern as such, since it’s calculated dynamically.

Note that since I’ve been unable to find definitive published statements from Canon on this topic it isn’t as authoritative as it could be. Please contact me if you have further information about E-TTL flash metering.

 

[Valvebounce]

Hi PBD.
As always you are a wealth of information, thank you for sharing this with us, so much to take in.

Cheers, Graham.

 

[snegri45]

Flash color vs. ambient light color temperature.

The woman with the choker was shot under very benign lighting, hanging globes with what seemed like 5,500 K LEDs. I used Auto color balance. The other woman was shot in a lounge with cloudy daylight from a large window behind me, I don't remember the color of the artificial light in the lounge. In both shots there were no significant color issues with the ambient (lucky me!) Also, when you suppress the ambient by a stop you do at least reduce the color conflict.

The nightmare is a room with incandescent light that the Maitre D' turns way down to save electricity. The best way to deal with this is the gel. Slap a CTO (Color Temperature Orange) gel on your flash head. It works. If you are sneaky you can also set the camera white balance to incandescent and you avoid the all orange look.

 

[SumanV]

NK Guy was the person who documented the way E-TTL II works best but that was way back in 2001-2006. the site can still be retrieved via webarchive http://photonotes.org/articles/eos-flash/index2.html but below I have copied and pasted the most pertinent part. There are a lot more flash models now and a lot of his articles are not very relevant anymore as they include the older E-TTL and the even earlier A-TTL.

Hope this helps.

EOS flash photography confusion.


Program (P) mode flash.


Tv (shutter priority) mode flash.


Av (aperture priority) mode flash.


Manual (M) exposure mode flash.

• Set your camera to M for manual exposure mode.
• Set the aperture and shutter speed to expose the background correctly.
• Press the shutter button down halfway if your flash has a rear-panel LCD (liquid crystal display). The flash coupling range will appear in the flash unit’s LCD. This range is the distance that can safely be covered by the flash.
• If your lens has a distance scale you can check the current focussing distance to ensure that the distance to your subject falls within this range. Otherwise you’ll have to estimate.
• If the “flash ready” lightning bolt symbol appears in the viewfinder you can press the shutter all the way to take the photo. The flash’s TTL or E-TTL system will determine the flash exposure level of the subject.

Thank you for the wonderful information @privatebydesign. I have now understood how the flash works with various modes. I will experiment with the EOS RP and learn flash photography.

Best regards
Suman

 

[SumanV]

E-TTL flash metering patterns:

The camera uses its evaluative metering system to meter the flash output, based upon the preflash. When in autofocus mode most EOS bodies which do not use E-TTL II bias flash metering toward the currently selected AF point, but always in an evaluative mode pattern - they don’t use spot or partial metering patterns. When in manual focus mode it appears that at least some EOS bodies switch to centre-weighted averaging.

Note, however, that this biasing of E-TTL metering to the active point is potentially problematic, since it means that the flash metering is done in almost a spot-metering fashion. Many user complaints regarding flash metering problems in E-TTL mode appear to be linked to this issue. If the camera happens to be over a dark object, for example, flash metering can be considerably overexposed, and vice-versa. The standard answer to this problem is to use FEL and meter off something mid-toned, but this is clearly not a solution for rapid-shooting situations such as weddings and sports. Another approach is to set the camera lens to manual focus, since the body apparently switches to centre-weighted average metering in that mode, but that’s obviously not a useful answer much of the time either.

Users of the digital D30 and D60 have been particularly unhappy with E-TTL flash metering. The 10D apparently reduces this problem by defaulting to a centre-weighted averaging metering pattern in E-TTL, even when the lens is set to autofocus.

E-TTL II addresses this problem by altering flash metering considerably. It examines each evaluative metering zone before and after the E-TTL preflash. It then calculates the weighting for each zone independently, biasing against those zones with high reflectivity in the preflash. This means that E-TTL II does not have a flash metering pattern as such, since it’s calculated dynamically.

Note that since I’ve been unable to find definitive published statements from Canon on this topic it isn’t as authoritative as it could be. Please contact me if you have further information about E-TTL flash metering.

This is amazing! I thought that the metering mode specified will apply for ETTL. As per this information, when the camera is in autofocus mode, it will not use spot/partial metering but instead use evaluative metering. So, in that case, can there be instances when ETTL doesnt do its intended job? Does this mean that manual flash is the only way to go for precise control of lighting? Is there a way to know which metering mode has been chosen by the ETTL to calculate flash exposure? Is this information present in EXIF data?

Best regards
Suman

 

[SumanV]

Flash color vs. ambient light color temperature.

The woman with the choker was shot under very benign lighting, hanging globes with what seemed like 5,500 K LEDs. I used Auto color balance. The other woman was shot in a lounge with cloudy daylight from a large window behind me, I don't remember the color of the artificial light in the lounge. In both shots there were no significant color issues with the ambient (lucky me!) Also, when you suppress the ambient by a stop you do at least reduce the color conflict.

The nightmare is a room with incandescent light that the Maitre D' turns way down to save electricity. The best way to deal with this is the gel. Slap a CTO (Color Temperature Orange) gel on your flash head. It works. If you are sneaky you can also set the camera white balance to incandescent and you avoid the all orange look.

View attachment 189717

Thank you @snegri45 for the tips!

Best regards
Suman

 

[privatebydesign]

This is amazing! I thought that the metering mode specified will apply for ETTL. As per this information, when the camera is in autofocus mode, it will not use spot/partial metering but instead use evaluative metering. So, in that case, can there be instances when ETTL doesnt do its intended job? Does this mean that manual flash is the only way to go for precise control of lighting? Is there a way to know which metering mode has been chosen by the ETTL to calculate flash exposure? Is this information present in EXIF data?

Best regards
Suman

I just wrote out a long reply but deleted it because the truth is this 2 page article does a much better job. The earlier answer might not have made the differences between E-TTL and E-TTL II clear enough and I apologize if I have caused confusion.

E-TTL II flash technology - Canon Professional Network

<div id="decoration_container"> <img src="./files/education/technical/E-TTL_II/header.jpg" alt="PowerShot G11 G11 II...

cpn.canon-europe.com

But yes, manual flash mode is the only way to get consistent and reliable output from the flash as in E-TTL II there are simply too many variables to process what the camera thinks it should do. However in most situations I find E-TTL II to be reliable enough to give me good enough exposures of what I want so I often use it in dynamic situations like receptions and functions where varying subject distances are simply too numerous to work the flash power accurately.

 

[scottkinfw]

Hi Suman

Great info posted. I have one slight disagreement with @Valvebounce. The shutter speed plays a role in the flash exposure in this situation. At slower shutter speeds, you begin to pick up more ambient light.

sek