550EX balanced fill flash

[doug_lee__cinnaminson__nj]

I am trying to understand CAnon ETTL flash and am somewhat confused.

I have an EOS 1V and 550EX flash. My understanding is that the camera

will automatically adjust for proper background exposure and the

flash will handle the exposure for the main subject. So, when I take

a manual meter reading with the 1V I get f2.8 at 1/15 and set the

camera accordingly. No problem.

 

However, if I change to Av or Tv mode the in-camera meter now

indicates the correct exposure is f2.8 at 1/30?? If I turn the flash

off the in-camera meter indicates that f2.8 at 1/15 is the correct

exposure. If I switch the flash back on the correct meter reading

goes back to f2.8 at 1/30. If I change the mode to Program now the

camera sets itself for f5.6 at 1/60. I am confused.

 

So, I can get three different "correct" exposures for the background

depending on the mode (P, Av, Tv, or M) I select. What really

confuses me is why the in-camera meter is affected by the flash being

off or on. That makes no sense to me, at all.

 

Any guidance is greatly appreciated. Thank you.

[Ken Katz]

This is the "bible" on such matters:

 

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

 

The behaviour in "P" mode is discussed in the above referenced article. The reduction in ambient exposure of up to 1 stop, in "Av" or "Tv" modes, in low light, has been discussed in this forum, and seems to be programed into EOS 3's and EOS 1V's (and maybe other newer bodies), and is not evident in older bodies such as Elan II. I think the camera is trying to save you from overexposing the main subject, but I agree, such "idiot proofing" has no place on pro level bodies.

[cliff_henry]

Doug,

 

I'm not a expert at this but if you will go to this site it will enlighten you considerably on the EOS flash system.

 

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

 

The basic thing that helped me w/this problem is understanding that background exposure is controlled by shutter speed and main subject flash exposure is controlled by aperture.

 

The above article will help w/how camera controls settings in each mode. After some test, I find I get best flash results in manual mode by setting shutter for background exposure and aperture, depending on DOF I want and distance to subject, and letting the flash control output for main subject exposure. This way, the balance between subject and background will be more natural.

 

Hope this helps.

 

Cliff

[doug_lee__cinnaminson__nj]

Thanks. At least I know it is not a problem with me or my camera. Yes, I expect idiot proofing when I set any camera to full program mode. But not Av, Tv or M. What I find "offensive" is the fact that the meter shows the "adjusted" exposure as correct. I want the meter to show a 1-stop underexposure. Oh well.

 

Thanks again. I can now go on to be confused about other matters. (-;

 

-Doug

[bill_goldman]

The camera is not displaying an "underexposure reading". It is showing the corrected exposure for the ambient light PLUS the effect of the added flash.

 

Also, it is important to keep in mind how flash works in each of the exposure modes. In P mode, flash will provide the primary illumination for the subject in dark conditions and provide auto fill in bright conditions. Av or Tv always expose for the ambient light with flash fill. The M mode allows you to select the shutter speed and aperture and the flash will provide the output for a correct exposure.

[henry_c]

When I want a +1 exposure for ambient and I add flash, I expect the camera to still give me a +1 exposure for ambient, flash or no flash. This way I can control accordingly. I don't like it when it does something and doesn't tell me, thinking it's better for me this way. I am pissed off with these kinds of useless features on a body like EOS1V. I think the best camera is the one that you can have control over the important things while it handles the boring things, like film rewind in insane speed.

[henry_c]

hmm, I just checked my 1V with 550 and don't seem to experience the same problem.

[henry_c]

I just tried again and it seems it does happen: when the reading is lower than a certain shutter speed the camera will under expose the ambient light when flash is on. But if it's higher than a certain speed, turning on or off of the flash won't affect it. I hate this.

 

Also, please, please stop just posting the NKguy's link to answer flash questions. It's just not fun to see someone ask a specific question, then to have someone posting a link. I mean I know you want to help, but it's like asking where can I find a grocery store and the kind stranger tells me a name of a city. Please, pin point to a certain area of NKguy's page if you must link to it that answers the question, then say here this link might give you more info.

 

Just two cents.

[doug_lee__cinnaminson__nj]

Henry, I agree. I expect program mode to make decisions for me, but not any other mode. Think I'll stick with manual mode for now.

 

I used to have a Nikon system. (F5, SB-28, etc.) I don't recall flash being quite so quirky. But, I never used it that much.

 

Regards,

Doug

[bill_goldman]

Hearing all these complaints about the camera making decisions for you so you can take control and make stupid mistakes reminds me about many years ago when I bought my first SLR - a Pentax Spotmatic.

 

I thought it was pretty sophisticated because it had center-weighted-average, match-needle, thru-the-lens metering. It didn't have auto-loading, auto ISO setting, auto film advance, auto rewind, auto focus, auto-exposure, multiple metering systems, or multi-exposure modes.

 

It allowed me to make all the decisions. I took some pretty good pictures but I also made a lot of stupid mistakes and took some pretty bad pictures.

 

I've learned not to complain about modern cameras like the EOS-1v. I still make a few bad decisions but I don't make any stupid mistakes. And I get a lot of great pictures. And I've learned that just maybe the camera designers are smarter than I am and that prevents me from making stupid mistakes I'm not too proud to accept it.

 

And, Henry, if you want to overexpose the ambient light by one stop and then add flash, more power to you. Enjoy your washed out pictures.

[henry_c]

Bill, in case you are so indulged in slides and don't shoot negative film, then I forgive ya for your obvious ignorance in exposing negative. The more over-exposed they are (to a certain degree, of course, according to the negative) the easier to print them. If you have done dark room (or just shot negative in general) then you would know what I am talking about. They won't be washed out, but the lab will thank you for exposing them nicely for easier printing.

 

If not, more power to you, too.

[bill_goldman]

I know that erring on the side of overexposure for color print film and erring on the side of underexposure for slides is the rule - if you're going to err, that is. I always strive for ideal exposures, rather than helping the lab technician. After all, most prints are made by automatic, dumb machines, anyhow. And you're right, I do shoot slides --- because I don't want a dumb machine (or a dumb technician) making decisions for me. Also, I am not completely inexperienced when it comes to the developing and printing process.

[henry_c]

Exactly, therefore, you would know that a +1 compensation with fill flash gives quite an ideal exposure, and not washed out photos. It is not for the lab's sake, it's because, well, as we all know: more details on the negative so it's easier to get a nice glossy print.

 

Also, for weddings, slides is just not very ideal.