Approve the Cookies
This website uses cookies to improve your user experience. By using this site, you agree to our use of cookies and our Privacy Policy.
OK
Index  •   • New posts  •   • RTAT  •   • 'Best of'  •   • Gallery  •   • Gear  •   • Reviews
Guest
New posts  •   • RTAT  •   • 'Best of'  •   • Gallery  •   • Gear  •   • Reviews
Register to forums    Log in

 
FORUMS General Gear Talk Flash and Studio Lighting 
Thread started 10 Feb 2014 (Monday) 09:06
Search threadPrev/next
sponsored links
(this ad will go away when you log in as a registered member)

ETTL in P, Av, Tv vs. M Modes

 
Roxie2401
Senior Member
Avatar
355 posts
Likes: 2
Joined Jan 2009
Location: Western PA
     
Feb 10, 2014 09:06 |  #1

I know I've read about this but can't find the thread(s) or put together a correct "Search" criteria (ETTL + Auto, etc.) to find it again. I apologize in advance for a repeat topic discussion.

Does ETTL react differently (in Canon terms) when used in "auto" modes (P, Av. TV) as compared to being used in full Manual mode?

Is it acting like "fill" flash in auto? Or am I totally confused about ETTL?

Thanks




  
  LOG IN TO REPLY
sponsored links
(this ad will go away when you log in as a registered member)
gonzogolf
dumb remark memorialized
29,692 posts
Gallery: 132 photos
Best ofs: 1
Likes: 4536
Joined Dec 2006
     
Feb 10, 2014 09:38 |  #2

I dont want to be vague, but it sort of depends.
You need to start with the undersanding that each flash photograph has two exposure values, one if the flash, and the other is the ambient light in the part of the scene not lit by the flash. It sounds basic but some users dont consider that.

ETTL doesnt change, that is the auto feature of the flash system doesnt change dependent on mode, but the camera does respond differently. Let me explain. In AV and TV mode ( I admit I dont have a clue about P mode but suspect its the same as the other auto modes) when you use the flash in ETTL mode the programming of the camera tries to do most of the work with the camera first. What I mean by that is that in AV mode it tries to use a combination of shutter speed and flash power to keep the flash relatively balanced with the ambient (which we call fill flash). In TV mode it sort of does the same adjusting the aperture and flash power to give you that same balance. The common denominator is that the programming assumes you dont want flash so bright that your background is dark which used to be very common before ETTL.

Once you switch to M the flash still tries to give you the same exposure it did before, but now its getting less help from the camera programming so it appears to be behaving differently. The flash is still trying to get the correct exposure, but the photographer decides by selecting the M setting he wants how much balance the flash and the ambient will have. If you set your Aperture at f16 and shutter speed at 1/200 of a second in an average room the flash will have to pump out full power to illuminate the subject. If you were in that same room in av mode and selected f16, the camera would default to 1/10 of a second trying to balance the ambient to the flash output so the background wouldnt be totally black, but of course that would be below handholdable speed.




  
  LOG IN TO REPLY
apersson850
Cream of the Crop
Avatar
12,179 posts
Gallery: 10 photos
Likes: 374
Joined Nov 2007
Location: Traryd, Sweden
     
Feb 10, 2014 09:49 as a reply to  @ gonzogolf's post |  #3

If you use P mode, it will attempt to expose the background properly using ambient light. It will use the full aperture range and shutter speeds in the range 1/60 - shortest sync speed to accomplish this. If that's not possible, there will be under- or overexposure.


Anders

  
  LOG IN TO REPLY
Wilt
Reader's Digest Condensed version of War and Peace [POTN Vol 1]
Avatar
43,050 posts
Gallery: 1 photo
Likes: 2999
Joined Aug 2005
Location: Belmont, CA
     
Feb 10, 2014 09:55 |  #4

ETTL is absolutely the same in flash output regardless of Green Box or P or Av or Tv mode.

What varies by mode is merely how the camera behaves for ambient light exposure, the specific selection of shutter/aperture. But if the combination of shutter + aperture is the same, regardless of mode the outcome photo will be the same.


You need to give me OK to edit your image and repost! Keep POTN alive and well with member support https://photography-on-the.net/forum/donate.p​hp
Canon dSLR system, Olympus OM 35mm system, Bronica ETRSi 645 system, Horseman LS 4x5 system, Metz flashes, Dynalite studio lighting, and too many accessories to mention

  
  LOG IN TO REPLY
OceanRipple
Member
244 posts
Joined Jan 2014
Location: UK
     
Feb 10, 2014 10:11 |  #5

The OP may find this video helpful (esp sections 2 to 7);

http://cpn.canon-europe.com …asterclass/cano​n_flash.do (external link)




  
  LOG IN TO REPLY
digital ­ paradise
I still have 8 digits left
Avatar
16,081 posts
Gallery: 112 photos
Likes: 10522
Joined Oct 2009
Location: Canada
     
Feb 10, 2014 10:25 |  #6

Wilt wrote in post #16678340 (external link)
ETTL is absolutely the same in flash output regardless of Green Box or P or Av or Tv mode.

What varies by mode is merely how the camera behaves for ambient light exposure, the specific selection of shutter/aperture. But if the combination of shutter + aperture is the same, regardless of mode the outcome photo will be the same.

We can probably add M mode to that as well.


Image Editing OK

Website (external link) ~ Buy/Sell Feedback

  
  LOG IN TO REPLY
Wilt
Reader's Digest Condensed version of War and Peace [POTN Vol 1]
Avatar
43,050 posts
Gallery: 1 photo
Likes: 2999
Joined Aug 2005
Location: Belmont, CA
     
Feb 10, 2014 10:28 |  #7

digital paradise wrote in post #16678413 (external link)
We can probably add M mode to that as well.

Yep, I inadvertantly left if off my list although I intended to list M among them.


You need to give me OK to edit your image and repost! Keep POTN alive and well with member support https://photography-on-the.net/forum/donate.p​hp
Canon dSLR system, Olympus OM 35mm system, Bronica ETRSi 645 system, Horseman LS 4x5 system, Metz flashes, Dynalite studio lighting, and too many accessories to mention

  
  LOG IN TO REPLY
digital ­ paradise
I still have 8 digits left
Avatar
16,081 posts
Gallery: 112 photos
Likes: 10522
Joined Oct 2009
Location: Canada
     
Feb 10, 2014 10:40 |  #8

You flash has two options - Evaluative and Average. This has nothing to do with similar named camera modes.

Evaluative mode. There are multiple metering zones. You press shutter half way and the camera gets an ambient reading. You press the shutter all the way and the flash pre fires. It compares the ambient reading to the light reflected back from the pre flash, isolates the closet object which is typically your subject. Now ETTL tells the flash how much power to use to produce a good exposure of your subject. Like Wilt said this applies to all camera modes.

It works exactly like your camera meter does when there is no flash on it. If you take picture of black tar, white snow or an equal amount of tar and snow in the frame you will likely have to use EC (Exposure Compensation) to for the tar and snow only shots. The tar and snow in the same frame shot will be more balanced. Depending on what your subjects are wearing and how reflective it is when the flash is on you may have to fine tune the FEC (Flash Exposure Compensation).

Average mode does not isolate the subject, it just averages out the whole scene. You still have to use FEC but people say it can be more accurate for indoor flash shooting. Not so good for outdoor.


Image Editing OK

Website (external link) ~ Buy/Sell Feedback

  
  LOG IN TO REPLY
digital ­ paradise
I still have 8 digits left
Avatar
16,081 posts
Gallery: 112 photos
Likes: 10522
Joined Oct 2009
Location: Canada
     
Feb 10, 2014 11:03 |  #9

As to fill flash. I hate that they named it fill flash because it is not filling in anything. It is just less flash and is again not effected by any camera modes. It is called AFR or Auto Fill Reduction and strictly works on the ambient light conditions. As the ambient gets brighter it just reduces flash power by ½ stops.

Unless you own the 1DX it cannot be disabled and there is nothing you can do about it. It just does it's thing.


Image Editing OK

Website (external link) ~ Buy/Sell Feedback

  
  LOG IN TO REPLY
Roxie2401
THREAD ­ STARTER
Senior Member
Avatar
355 posts
Likes: 2
Joined Jan 2009
Location: Western PA
     
Feb 10, 2014 11:08 |  #10

digital paradise wrote in post #16678500 (external link)
As to fill flash. I hate that they named it fill flash because it is not filling in anything. It is just less flash and is again not effected by any camera modes. It is called AFR or Auto Fill Reduction and strictly works on the ambient light conditions. As the ambient gets brighter it just reduces flash power by ½ stops.

Unless you own the 1DX it cannot be disabled and there is nothing you can do about it. It just does it's thing.


Can you expand a little on how the Canon products (say 5D MK III + 580EX II) accomplish "fill flash?" What camera/flash settings activate it, etc.?

Thanks




  
  LOG IN TO REPLY
digital ­ paradise
I still have 8 digits left
Avatar
16,081 posts
Gallery: 112 photos
Likes: 10522
Joined Oct 2009
Location: Canada
     
Feb 10, 2014 11:08 |  #11

Depending on how interested you are we can provide more information on how AFR works. Just let us know. There are also other things going on in the background which again you have no control over so there is no real need to know, it is just interesting. It is Canon's attempt to make your subject pop when using the flash.


Image Editing OK

Website (external link) ~ Buy/Sell Feedback

  
  LOG IN TO REPLY
Roxie2401
THREAD ­ STARTER
Senior Member
Avatar
355 posts
Likes: 2
Joined Jan 2009
Location: Western PA
     
Feb 10, 2014 11:11 |  #12

digital paradise wrote in post #16678512 (external link)
Depending on how interested you are we can provide more information on how AFR works. Just let us know. There are also other things going on in the background which again you have no control over so there is no real need to know, it is just interesting. It is Canon's attempt to make your subject pop when using the flash.


This may be where I'm having difficulty in getting the subject properly illuminated and not blowing out the rest of the scene. Maybe I've been thinking I just don't understand ETTL when it is really what you call AFR.

If you can, please point me to more detail on AFR.




  
  LOG IN TO REPLY
digital ­ paradise
I still have 8 digits left
Avatar
16,081 posts
Gallery: 112 photos
Likes: 10522
Joined Oct 2009
Location: Canada
     
Feb 10, 2014 11:12 |  #13

Roxie2401 wrote in post #16678511 (external link)
Can you expand a little on how the Canon products (say 5D MK III + 580EX II) accomplish "fill flash?" What camera/flash settings activate it, etc.?

Thanks

Sure, give me a few minutes.


Image Editing OK

Website (external link) ~ Buy/Sell Feedback

  
  LOG IN TO REPLY
digital ­ paradise
I still have 8 digits left
Avatar
16,081 posts
Gallery: 112 photos
Likes: 10522
Joined Oct 2009
Location: Canada
     
Feb 10, 2014 11:23 |  #14

This is a test for me. I learned all this stuff from Wilt and Gonzo.

It works on EV or Exposure Value. Depending on the selected ISO, EV is the shutter and aperture combinations to produce a correct exposure when not using a flash.

Here is a typical EV chart. Ever hear of the sunny 16 rule? ISO 100, 1/100 @ f16. If you look at the bottom left hand corner you can see EV as related to the scene. EV 15 = direct sunlight. Now if you go to the chart and locate EV 15 you can find the correct shutter and aperture combinations to get a good exposure. You could use this chart if your light meter failed to work.

PHOTOBUCKET EMBEDDING IS DISABLED BY THIS MEMBER.
Photobucket sends ads instead of embedding photos from their free galleries.
Click the link (if available) below to see the image in a gallery page.

http://i33.photobucket​.com …_zpsd3098457.jp​g~original (external link)


The point where AFR kicks in at EV 10. As you can there is something called NEVEC which I will explain in the next post. However if you look at AFR part at EV 10 the flash power is reduced by ½ stop. At 11 -1 stop, at 12 -1 ½ and so on.

So you can see AFR which is fill flash does not miraculously produce a good fill exposure. It just reduces flash power and you still need to fine tune FEC at times.

PHOTOBUCKET EMBEDDING IS DISABLED BY THIS MEMBER.
Photobucket sends ads instead of embedding photos from their free galleries.
Click the link (if available) below to see the image in a gallery page.

http://i33.photobucket​.com …_zps48594afb.jp​g~original (external link)

Image Editing OK

Website (external link) ~ Buy/Sell Feedback

  
  LOG IN TO REPLY
digital ­ paradise
I still have 8 digits left
Avatar
16,081 posts
Gallery: 112 photos
Likes: 10522
Joined Oct 2009
Location: Canada
     
Feb 10, 2014 11:35 |  #15

NEVEC = Negative Evaluative Exposure Compensation. To create more subject pop Canon purposely underexposes the ambient by 1 stop at an EV of 10 or lower.

Now you see what the effective ambient:flash ratios are depending on the EV. At EV 10 the flash ambient and flash balances out. This is at ISO 400. When the ISO changes that all the values change as well so Canon is really messing with you. No camera can disable NEVEC as far as I know and only the 1DX can disable AFR.

Here is an extended chart of EV values which tells you where AFR and NEVEC kick in. Two parts as it was too long to capture on my screen.

PHOTOBUCKET EMBEDDING IS DISABLED BY THIS MEMBER.
Photobucket sends ads instead of embedding photos from their free galleries.
Click the link (if available) below to see the image in a gallery page.

http://i33.photobucket​.com …_zps06cf29f7.jp​g~original (external link)


PHOTOBUCKET EMBEDDING IS DISABLED BY THIS MEMBER.
Photobucket sends ads instead of embedding photos from their free galleries.
Click the link (if available) below to see the image in a gallery page.

http://i33.photobucket​.com …_zps90aa74f2.jp​g~original (external link)

Image Editing OK

Website (external link) ~ Buy/Sell Feedback

  
  LOG IN TO REPLY
sponsored links
(this ad will go away when you log in as a registered member)

6,286 views & 0 likes for this thread
ETTL in P, Av, Tv vs. M Modes
FORUMS General Gear Talk Flash and Studio Lighting 
AAA
x 1600
y 1600

Jump to forum...   •  Rules   •  Index   •  New posts   •  RTAT   •  'Best of'   •  Gallery   •  Gear   •  Reviews   •  Member list   •  Polls   •  Image rules   •  Search   •  Password reset

Not a member yet?
Register to forums
Registered members may log in to forums and access all the features: full search, image upload, follow forums, own gear list and ratings, likes, more forums, private messaging, thread follow, notifications, own gallery, all settings, view hosted photos, own reviews, see more and do more... and all is free. Don't be a stranger - register now and start posting!


COOKIES DISCLAIMER: This website uses cookies to improve your user experience. By using this site, you agree to our use of cookies and to our privacy policy.
Privacy policy and cookie usage info.


POWERED BY AMASS forum software 2.1forum software
version 2.1 /
code and design
by Pekka Saarinen ©
for photography-on-the.net

Latest registered member is Guashumerda
815 guests, 194 members online
Simultaneous users record so far is 15144, that happened on Nov 22, 2018

Photography-on-the.net Digital Photography Forums is the website for photographers and all who love great photos, camera and post processing techniques, gear talk, discussion and sharing. Professionals, hobbyists, newbies and those who don't even own a camera -- all are welcome regardless of skill, favourite brand, gear, gender or age. Registering and usage is free.