View Full Version : a quick flash question

08-17-2006, 09:22 AM
usually when useing the 420EX i just shoot...the cam is supposed to figure it all out and it does a pretty decent job. My question is... if i set the camera for, say... -1 or-2 FEC, does this mean it will make the flash brighter or darker?

08-17-2006, 09:39 AM
I've also got the 420EX flash, but sorry I can't answer your question, I do however have one of my own. When I use my flash and I try to shoot in AV or TV it acts strange, at least to me, if I set anything other than 1/60 @ 4.5 one or the other thats flashes. Say I set f8 the stupid shutter speed will drop to 15 sec. If I dial in P or AUTO the camera sets to 1/60 f4.5, is it my flash? is it the camera not picking up the flash? or is this normal?
confused as usual.

08-17-2006, 09:51 AM
iv had this happen, when useing it for macros.. if i set the shutter really fast and the aperture to say f4 or f 5, the camera says it wont work and the shutter speed flashes..i shoot anyways and it usually gives good results. Canons flash directions are really sketchy at most.

08-22-2006, 02:50 PM
Canons flash directions are really sketchy at most.

does anyone know of a good "Instructional" type manual for the canon flashes...particularly the 420EX?

does it work the same as a 550 or 580 in regards to useage? besides the fact its not manually set and its smaller?

08-22-2006, 03:20 PM
The best thing i could think to use my 420ex when i had it was for a slave. I think I might have a Stofen Omnibounce to fit that flash for you Craig (it might be the 500 size, i have to check the size). If you wanna meet sometime this week or something, I'll let you have it --but lemme check the size 1st)

I'd imagine the FEC would help somewhat, but you're still limited on how far down you can stop.

08-22-2006, 03:50 PM
cool... but i got one...lol

we can definetly plan some sort of ct. meet when i get back from VA in two weeks... (after labor day) maybe go up to one of these places in the hot spots.. i think there are a few from ct. here now...lol

08-22-2006, 04:15 PM
i now pack bugspray in my camera bag... so i'm ready! lol

08-22-2006, 04:16 PM
I'll try to answer the questions that have accumulated in the thread.

First question... FEC is kind of like EC, but for flash. FEC = Flash Exposure Compensation, and EC = Exposure Compensation. With EC, if you are shooting in an auto mode (anything by M), then the camera is metering and will determine settings for a proper exposure. If you want to change it, then you can apply EC + or -. EC (and FEC) is measured in "stops" of light. Most cameras have a granularity of 0.3 stops and can be adjusted as much as +/- 2 stops or more. Theoretically, you could adjust the aperture, shutter speed, or ISO and accompish the same thing. With FEC, it works the same way. The flash is determining how much power to apply, and then you decide you want less... so you apply FEC. It is also measured in stops, but it isn't exactly the same equivalent to EC stops. If you get into studio lighting and using a meter, you'll find that you measure the light in stops. The meter will tell you that you are getting "f/4" so you would adjust your strobe down "stop" increments to reach your desired output. With an EOS flash, they are adjust manually in percentages of full power... 1/1, 1/2, 1/16, etc... so it doesn't directly apply. All you really need to know is that FEC allows you to alter the automatic flash calculation up or down.

With regard to EOS flash behavior in Tv, Av, and M, vs. how they behave in P, this is the way the flash operates. In P, the flash calculates settings for the flash to be the primary light source (always). In the other modes, the flash calculates settings for the flash to be fill only (always). You can't change this behavior, it is the only way it works. With Nikon flashes like the SB-800, there is a setting for fill, and a setting for key... you decide. So, if you are shooting in a mode other than P, YOU need to figure out how you want the background lit and adjust the settings accordingly. Then the flash will provide fill to take care of the subject. You set the background, the flash automatically fills the foreground. The other thing that can mess you up in these modes is if you try to set a shutter speed faster than the max sync speed of the camera. I've run into this when going back and forth between flash and no-flash. I'm setup shooting without it, and then just flip it on for fill, without looking at the settings. It clips the shutter speed at the max sync speed and you'll get an overexposed image most likely.

08-22-2006, 04:17 PM
Oh, and I forgot the last question... the best source of Canon flash information is - http://photonotes.org/articles/eos-flash/ . If you go through all of it, you will no everything there is to know about a Canon flash.

08-23-2006, 08:01 AM
well, so far Mikes link in the above post has answered one question and ive only been reading the website for 5 minutes..thanks mike!

"I tried to take a flash photo and the camera wanted a really slow shutter speed. Why?
This occurred because you are trying to take a flash photo in low-light conditions and the camera is in Av (aperture priority) mode or the night PIC (icon) mode if your camera has it.
In Av, night and Tv (shutter speed priority) modes the camera meters for ambient (existing) light and fills in the foreground subject (http://photonotes.org/articles/eos-flash/index2.html#subjectbackground) using the flash. It does not assume that the primary light source is the flash, and therefore the shutter speed it sets is the same as it would set if you weren’t using flash at all.
In low light this results in slow shutter (http://photonotes.org/articles/eos-flash/index2.html#slowshutter) photography. If the shutter speed is very long you will, therefore, need a tripod to avoid motion blur during the exposure.
Alternatively you can switch to full auto (green rectangle) or Program (P) mode (http://photonotes.org/articles/eos-flash/index2.html#programflash), which automatically expose for the flash-illuminated subject and not the background. These modes try to ensure that the shutter speed is high enough to let you handhold the camera without a tripod. The drawback of P and basic modes is that photos taken in dimly lit areas usually end up with black or poorly lit backgrounds."

Now that I know this I feel safer shooting with flash in AT-TV modes... and knowing that it will fill only and NOT light up the BG (if i dont want to) is a good thing... (wish I knew this before going into the prison) And also knowing that it shouldnt "blow out" the forground ( like in my prison shots, the fore ground looks pretty decent) and that I can go to M- mode and light up the whole scene.

08-23-2006, 10:03 AM
I don't think you want to make the assumption that in P it will light up the whole scene, as I don't think that's the case. In fact, you are much MORE likely to get the "flashed" look in P, than in the other modes. The reason for that is that given many scenes, it may be pretty hard for the single flash to light the background and the foreground. It will try to meter the whole scene and apply flash to light it, but if there is great separation between parts of it, then its not going to work. In the other modes, YOU can make sure the background is lit, and let the flash worry about the rest... since you can open things up a bit. Thats just my experience. I do often try P first to see what its going to do... and if I like the look then I go will often go with it, or use those settings as a starting point in M.

08-23-2006, 10:11 AM
i know, its just how it read, now..looking at the manual i see it isnt so cut and dry. lol But, what i got was, in P and auto, the camera will meter for the whole scene and throw more light.. in av, tv and m it will assume your just filling and throw less light thus focusing on the subject as fill light. which is good, except for like i said, in the mines down inside the prison, it would have been nice if i could have had more light in the BG s well but i also think if i had done so, it (the flash) would have possibly blown out the fore ground.. plus i screwed up by having the camera in AV mode.. I planned onTV mode but i stopped on the way in to take a pic of a little girls shoe that was sitting on a rock wall (for my "forgotten" series im doing on my site) and since it was a sorta close up, i put the cam into AV and then forgot to change it back...lol
Man, this flash thing is really kind confusing me.. thanks for posting that link though, at least now im not feeling so lost.

08-23-2006, 10:47 AM
You are almost always going to be better off metering ambient first and figuring out what you need to get the most light on the scene, and then supplementing with flash. The reality is that there will be many scenes where a digital SLR doesn't have the dynamic range to span the luminosity of the scene, because of the distance separating the things in the scene, and the light sources available.