Home · Register · Search · View Winners · Software · Hosting · Software · Join Upload & Sell

Moderated by: Fred Miranda
Username   Password

  New fredmiranda.com Mobile Site
  

FM Forums | Lighting & Studio Techniques | Join Upload & Sell

1
       2       end
  

Flash TTL question
  
 
Robin Usagani
Offline
• • • •
Upload & Sell: Off
p.1 #1 · Flash TTL question


If your camera is in manual (aperture, iso, shutter are set), is flash TTL affected by the metering mode on your camera? Googling doesn't yield good results. Not a lot of documentations on this.


May 30, 2013 at 05:28 AM
erichard
Offline
• • •
Upload & Sell: Off
p.1 #2 · Flash TTL question


On Canon, I believe Aperture priority makes TTL work in a "fill" mode, preserving the background at a properly exposed level if possible given sync speed limitations, ISO, brightness of the scene, etc. In manual, it isn't trying to do this (can't do this as you are setting the background exposure yourself in manual).
See:
http://photonotes.org/articles/eos-flash/index2.html#confusion



May 30, 2013 at 05:49 AM
gpop
Offline
• • •
Upload & Sell: On
p.1 #3 · Flash TTL question


erichard wrote:
On Canon, I believe Aperture priority makes TTL work in a "fill" mode, preserving the background at a properly exposed level if possible given sync speed limitations, ISO, brightness of the scene, etc. In manual, it isn't trying to do this (can't do this as you are setting the background exposure yourself in manual).
See:
http://photonotes.org/articles/eos-flash/index2.html#confusion



this is my understanding as well.
I believe that in manual mode (body) and ettl, the flash will attempt to light the entire scene, rather than just fill the subject. you may need to ride the flash compensation in order to light just the subject properly.

I think this is also the case in Tv mode.



May 30, 2013 at 07:10 PM
BrianO
Offline
• • • • •
Upload & Sell: On
p.1 #4 · Flash TTL question


Robin Usagani wrote:
If your camera is in manual (aperture, iso, shutter are set), is flash TTL affected by the metering mode on your camera?


Yes, at least in the case of Canon cameras. The preflash will be read from the same area as the selected metering pattern: spot, center-weighted, evaluative, etc.

For example, if you use spot metering (I often do) you can set the spot over a particular area of the image, press the * or FEL button (depending on camera and settings) to initiate a flash reading and lock in the value, and then recompose and take the shot. That can give a different level of flash output than taking the same shot without Flash Exposure Lock if the two areas that the spot falls on have different exposure values.

Note that in Manual exposure mode, ETTL Autoflash will try to light the metered subject to a middle gray EV.

Edited on May 30, 2013 at 09:09 PM · View previous versions



May 30, 2013 at 09:05 PM
Robin Usagani
Offline
• • • •
Upload & Sell: Off
p.1 #5 · Flash TTL question


BrianO, can you provide a link to verify this?


May 30, 2013 at 09:08 PM
BrianO
Offline
• • • • •
Upload & Sell: On
p.1 #6 · Flash TTL question


Robin Usagani wrote:
BrianO, can you provide a link to verify this?


I looked, but can't find anything at the moment.

I checked my 7D manual and my 580EX manual, and they don't really say much either. The 7D manual says that you need to select either Average or Evaluative in the ETTL Menu, so I may be wrong about it being set to the same area as the Metering Mode.

Both do, however, say that using FEL "locks the correct flash exposure setting for any part of the scene." (Emphasis added.)

I'm at work now (on my lunch break), but when I get home tonight I'll see if I can find out anything more. I think I still have notes from my last photography class or something along those lines. Speedliter's Handbook, maybe?



May 30, 2013 at 09:24 PM
cgardner
Offline
• • • • •
Upload & Sell: Off
p.1 #7 · Flash TTL question


...

Edited on May 31, 2013 at 07:28 PM · View previous versions



May 31, 2013 at 02:55 AM
Robin Usagani
Offline
• • • •
Upload & Sell: Off
p.1 #8 · Flash TTL question


cgardner.. I dont think you answered the question.


May 31, 2013 at 03:33 AM
BrianO
Offline
• • • • •
Upload & Sell: On
p.1 #9 · Flash TTL question


Robin Usagani wrote:
cgardner.. I dont think you answered the question.


SSDD.



May 31, 2013 at 03:38 AM
Robin Usagani
Offline
• • • •
Upload & Sell: Off
p.1 #10 · Flash TTL question


I have a black canon charger on my white wall. I used manual, spot metering and ETTL flash. Then I shot it with center weighted average. Both flash output looks the same.


May 31, 2013 at 03:44 AM
 

Search in Used Dept. 



BrianO
Offline
• • • • •
Upload & Sell: On
p.1 #11 · Flash TTL question


Robin Usagani wrote:
I have a black canon charger on my white wall. I used manual, spot metering and ETTL flash. Then I shot it with center weighted average. Both flash output looks the same.


What happens if you use FEL on the black charger?



May 31, 2013 at 04:07 AM
cgardner
Offline
• • • • •
Upload & Sell: Off
p.1 #12 · Flash TTL question


...

Edited on May 31, 2013 at 07:28 PM · View previous versions



May 31, 2013 at 01:26 PM
DigMeTX
Offline
• • •
Upload & Sell: Off
p.1 #13 · Flash TTL question


cgardner wrote:
I did actually, you just didn't understand the answer .

Regardless of exposure control ( manual or metered by camera) the flash metering performs a separate ambient metering as a baseline for comparing what the flash adds to each zone. In metered exposure modes like Av turning on flash will change exposure settings. That automatic compensation for flash overlap varies with brightness of the ambient and can be prevented by setting shutter / aperture manually.



Maybe I'm dim but I'm not understanding what your answer has to do with TTL readings in spot vs. center-weighted vs. evaluative in manual mode only.

brad Cook



May 31, 2013 at 01:55 PM
cgardner
Offline
• • • • •
Upload & Sell: Off
p.1 #14 · Flash TTL question


...

Edited on Jun 05, 2013 at 10:30 PM · View previous versions



May 31, 2013 at 02:00 PM
Jamesbjenkins
Offline
• • •
Upload & Sell: On
p.1 #15 · Flash TTL question


^ tl;dr


May 31, 2013 at 02:05 PM
cgardner
Offline
• • • • •
Upload & Sell: Off
p.1 #16 · Flash TTL question


Jamesbjenkins wrote:
^ tl;dr


Meters are designed to indicate an exposure that will render the measured surface as middle gray. The photographer must interpolate that reading to arrive at correct rendering.



May 31, 2013 at 02:07 PM
Jamesbjenkins
Offline
• • •
Upload & Sell: On
p.1 #17 · Flash TTL question


See. Now a few sentences are much friendlier than several paragraphs. Thank you!


May 31, 2013 at 02:16 PM
Jamesbjenkins
Offline
• • •
Upload & Sell: On
p.1 #18 · Flash TTL question


See. Now a few sentences are much friendlier than several paragraphs. Thank you!


May 31, 2013 at 02:16 PM
DigMeTX
Offline
• • •
Upload & Sell: Off
p.1 #19 · Flash TTL question


cgardner wrote:
Meters are designed to indicate an exposure that will render the measured surface as middle gray. The photographer must interpolate that reading to arrive at correct rendering.


Which still doesn't answer Robin's question. I think everyone in this thread understands what metering is. It's ok though it has now been answered in another thread.

brad



May 31, 2013 at 02:21 PM
Jamesbjenkins
Offline
• • •
Upload & Sell: On
p.1 #20 · Flash TTL question


Brad, I agree that it doesn't answer the question. I was making the point that there's no need for a novel every time you post.


May 31, 2013 at 02:38 PM
1
       2       end




FM Forums | Lighting & Studio Techniques | Join Upload & Sell

1
       2       end
    
 

You are not logged in. Login or Register

Username   Password    Retrive password