View Full Version : Flash photos in AV canon 30d
OK Im baffled!! No change there then!!! :D :lol:
I put my 30d on AV mode (having set in the custom functions.. the mode for having shutterspeed set at 1/250" when flash is used) as NO.. which means it DOESNT do that and i can have slower speed if I wish.
now with the sigma 500dg super attached in ETTL-II mode (ie, auto) the camera tells me when shooting a normal daylight interior for instance... that if I want to use F8 which sounds quite normal....the shutter speed will be 1/10".
The resulting photo is way overbright.
If i put the shutterspeed to what Id have thought was normal...ie 1/60" or something...im getting an aperture of 2.8 which wont give me enough dof.
Im waaaaay confused now.! i thought perhaps that i should just set the aperture to what i want and forget the shutterspeed.... but then im getting shutter staying open a long time to expose the background and this is all doing my head in!!! Even more!! :D
Just start shooting everything in manual janice, flash power included. It saves the confusion.
The camera will meter for the scene using existing light so the f/8 @ 1/10 is right. The flash will be used for fill only. As Kev suggested switch to manual then you can decide how much of the scene light can be used for the exposure and the flash will do the rest.
whitewash
23-06-2007, 11:18
me and a lad at work had a discussion about this a few months back, if you set the camera to manual and set your own requirements in that the flash tends to follow suit and expose the image correctly
Ahhh ww that explains it.
I did understand the problem Janice is having, because I was thinking about this the other week.
Basically the camera meters the scene for available light, and doesnt take the flash into account.
I didn't know if you set it up in manual, the flash then works out and exposes correctly.
whitewash
23-06-2007, 11:46
i think thats what we decided upon anyway, i cant remember completely though ive been asleep between then and now
Regardless of camera mode the flash basically does the same thing. A pre-flash is fired and is used to calculate how much power to use for the shot.
If you meter for the scene then you'll be using only a small amount of fill flash. The more you under-expose the more power the flash will use.
For example a night shot using manual mode. Meter for the street lights in the backgound, etc. and the flash lights the foreground.
http://www.pxl8.co.uk/web_5300.jpg
Keltic Ice Man
23-06-2007, 12:50
I HATE FLASH
Janice you are not alone - I can;t get my head around flash !! - in P mode and Auto yep with the sigma it works great. In AV or TV NO CHANCE!!
So I then think Manual - but haven;t a clue what settings to use, do I go off the in camera meter? Does it know there is a flash - I wish i understood
Well I do always use manual usually....when not using flash.
My question was actually appertaining to this wedding in august which is at noon so im thinking of keeping the flash on to fill in the shadows under ladies hats etc with the sun being up above.
I dont really want to have to up and down the flash power with each shot.. Id rather it do it automatically.
I didnt want to use manual all day....although I know it well...as I thought there would be more scope to go wrong. Spot metering is what I use but decided on that day to use matrix.
P mode sounded a good idea but with flash you cant use the shift feature so thats out.
The camera will meter for the scene using existing light so the f/8 @ 1/10 is right. The flash will be used for fill only. As Kev suggested switch to manual then you can decide how much of the scene light can be used for the exposure and the flash will do the rest.
But if it meters for the scene and decided F8 at 1/10" and I shoot at that..... the shutter speed is so slow you can hear it go click....click.
if someone moves Im buggered!
I think the problem is that people expect it to be more complicated than it really is, generally the flash will get it right without any effort. Try this when you've got 10 mins.
Get a willing subject, sit them in a chair with a table lamp next to them (switched on of course!).
Put the camera in manual and try the following.
Move in and get them to hold their hand near the light, take a reading from it and use those settings.
Take a shot with and without flash and compare. You should see that the flash shot has filled the darker side of the subject.
Now try another shot, this time take a reading from the table lamp itself so you're exposing for the brightest part of the scene. Then take a shot at the reading, -1 and -2 stops - all with flash. Now you can see how the flash automatically compensates to give the right amount of light for the shot.
If you feel the flash is too powerful you can adjust the FEC to knock it back a bit.
By controlling how you meter for the scene you are also controlling how much flash is used. The trick is to choose the right part of the scene to meter from in the first place and then balance the flash with FEC to get the result you want.
You can also try the same tests on a sunny day. Shoot with the sun behind and to one side of the subject. Expose for the highlights from the sun and let the flash fill the dark areas.
But if it meters for the scene and decided F8 at 1/10" and I shoot at that..... the shutter speed is so slow you can hear it go click....click.
if someone moves Im buggered!
Well, yes and no. It depends on the scene. If the person is in the foreground then they will be lit by the flash so the exposure time for them is the duration of the flash not the shutter. If you keep the background OOF then any blur from camera shake probably won't be noticable.
But this is why manual mode is the way to go, you can balance the settings so you get a usable shutter speed for the situation. You might have to lose some light from the scene or up the ISO but at least you have a choice over the balance of flash and available light.
The camera will meter for the scene using existing light so the f/8 @ 1/10 is right. The flash will be used for fill only. As Kev suggested switch to manual then you can decide how much of the scene light can be used for the exposure and the flash will do the rest.
Right...just been practising.:D Manual on camera (with spot metering) and manual on the flash.
I wanted a shot with a large aperture to give me small dof ... ie, of someone a fair way in front of the background so the background is oof. (ie, a bride's head and shoulders with some trees behind that are oof)
I exposed for the background using existing light .... and because the flash is attached to the camera I cant get a faster shutterspeed than 1/250" (as that is the flash sync speed) when using an aperture of F2.8 on my 50mm lens.
So when I shoot the subject the shutterspeed isnt fast enough adn there is way too much light. I assume the flash needs to be taken down a huuuuuge amount in manual in this situation?
This is where Im thinking that there's is going to need to be far too much fiddling between shots.
I also find it difficult that I dont meter off the bride's face for example.... and leave it to chance that the flash does it correctly...and if it doesnt i have to keep trying and turning it down and down.
Sounds terribly hit and miss to me. :shrug:
You can also try the same tests on a sunny day. Shoot with the sun behind and to one side of the subject. Expose for the highlights from the sun and let the flash fill the dark areas. How will the flash only fill the dark areas without blowing out the areas already lit by the sun? :shrug:
Does your flash do a high speed sync mode? I use it a lot on my 580ex for macro. I often shoot at 1/1000th or faster with flash.
Yes it does, Robert..... aaaarghhhh... more to get my head round!! LOL
How will the flash only fill the dark areas without blowing out the areas already lit by the sun? :shrug:
When the flash pre-fires the camera works out how much flash is needed to stop that happening. The light from the flash doesn't reach the bright background which you've exposed for, only the subject. ETTL is also tied to the focus point or centre point in manual focus.
If half the face is lit by the sun and half isnt.......then they are both at the same distance from the flash as each other.............how can the flash only ligh the dark half?
Everyone says I should use the flash on manual.....does that use ETTL then?
I'm with pxl8 on this I think people are making it far more complicated than it actually is. As long as the flashgun is set on ETTL the balance of flash to ambient light wont be far out regardless of which mode you actually use on the camera - including manual.
If anything the result may be a little too much, and after a test shot all I usually find necessary is to reduce flash power a little. Using bounce flash it may be necessary to increase power a little due to light loss, although generally speaking I find the ETTL system copes with bounce situations very well apart from extreme condition - high ceilings etc.
Thanks for that CT... i think i was confused by earlier on in the thread... people said to use manual on the camera AND manual flash too!
ETTL II sounds easier.
Made me seem thicker than I am!! :lol: if that's at all possible!
would you use spot or matrix btw?
and it doesnt matter that the shutterspeed is slow and it goes "click......click" and doesnt enable me to take shots quickly?
Everyone says I should use the flash on manual.....does that use ETTL then?
No it doesn't. Don't confuse Manual Mode on the camera with Manual Mode on the flash - they're two very different things.
When the flash is set to Manual - it's purely well... manual! It ouputs the exact same amount of light each time in accordance with what it's actual power is (indicated by it's Guide No). The only effect you can have on the flash power is either manually reducing it's output power, or by using the guide number to calculate the correct aperture for flash to subject distance, or the correct flash to subject distance for a given aperture setting.
Keltic Ice Man
24-06-2007, 21:08
If it makes you feel any better Janice - I'm as confused as you on this. I just did a dance show in a sport hall and the organiser asked me to do some group shots. The ceiling was too high to bounce so set AV so it was shutter 1/200 and f7.1, even with the flash head power setting on ETTL at +2 the flash was no where near good enough to light the kids, so had to change the ISO all the way to 1600 to get enough flash to light the pic. Should I have needed touch the ISO? What did i do wrong?
If half the face is lit by the sun and half isnt.......then they are both at the same distance from the flash as each other.............how can the flash only ligh the dark half?
Using random figures plucked out of the air... If the sunlit stuff is say 2000 lux and the shadow stuff is say 200.... and the flash adds 200 to the light level..... the sunlit area becomes 2200 (or plus 10%) and the shadow becomes 400 ( or twice as bright). So the change in the bright areas is not noticeable... but the dark areas is.
that's my wine fuelled theory anyway ;)
that's my wine fuelled theory anyway ;)
Well, my cider-fuelled brain has caught on there Robert! Well explained! :thumbs:
And thanks to everyone too.... for putting up with my inane questions.....its a topic I find it hard to come to grips with. :thumbs:
would you use spot or matrix btw?
In most situations Janice I'd use matrix. It's all to easy forget you're using spot metering and end up metering on a black suit or a white dress - using weddings as an obvious example. Thank gawd we can chimp like flip! ;)
and it doesnt matter that the shutterspeed is slow and it goes "click......click" and doesnt enable me to take shots quickly?
Well it can matter depending on the situation Janice.
Remember that the duration of the flash is incredibly brief - much faster than the fastest shutter speed on your camera,, so the shutter is still open long after the flash has died away. This is exactly what you want with a fill flash situation indoors as the ambient exposure which happens while the shutter is still open (after the flash has died) is what gives you that natural looking interior shot instead of the sudden fall off into darkness behind your subjects. Sometimes the ambient light can be strong enough for secondary images to record from subject movement during this period before the shutter closes, so if it's typically an exposure of say 1/25 or less just ask your subjects to keep still. :)
If it makes you feel any better Janice - I'm as confused as you on this. I just did a dance show in a sport hall and the organiser asked me to do some group shots. The ceiling was too high to bounce so set AV so it was shutter 1/200 and f7.1, even with the flash head power setting on ETTL at +2 the flash was no where near good enough to light the kids, so had to change the ISO all the way to 1600 to get enough flash to light the pic. Should I have needed touch the ISO? What did i do wrong?
Try to remember that flash lighting is only affected by two things during exposure which are ISO and Aperture. You'd have been better off opening up the aperture than upping the ISO to increase the effect of the flash but if you needed more light overall you could have decreased the shutter speed depending on the length of the lens you were using.
If it makes you feel any better Janice - I'm as confused as you on this. I just did a dance show in a sport hall and the organiser asked me to do some group shots. The ceiling was too high to bounce so set AV so it was shutter 1/200 and f7.1, even with the flash head power setting on ETTL at +2 the flash was no where near good enough to light the kids, so had to change the ISO all the way to 1600 to get enough flash to light the pic. Should I have needed touch the ISO? What did i do wrong?
This is where the guide number comes into play. That tells you how powerful your flash is for lighting a certain distance. I don't remember much more about it as I only used it back when I had a basic manual flash on a film camera.
So yes it is possible you might need to up the iso. Diffusers and wide angles all make it harder for the flash.
If it makes you feel any better Janice - I'm as confused as you on this. I just did a dance show in a sport hall and the organiser asked me to do some group shots. The ceiling was too high to bounce so set AV so it was shutter 1/200 and f7.1, even with the flash head power setting on ETTL at +2 the flash was no where near good enough to light the kids, so had to change the ISO all the way to 1600 to get enough flash to light the pic. Should I have needed touch the ISO? What did i do wrong?
Do this NOW in the room wherever you are... ;)
Set the camera on a tripod.- AV mode, 100 or 200 ISO, Meter for the room light - let's say its 1/25 or less with the lens wide open. USE THAT SETTING FOR YOUR FLASH SHOT. Attach the flashgun. Set it to ETTL and make sure it's on full power. Point the flash right up at the ceiling - take the shot.
Go on - tell us what happens. :)
Keltic Ice Man
24-06-2007, 21:23
Kev - If I had dropped the Aperture - with 2 lines of kids I wouldn't have had enough DOF would I?
I Couldn't drop the Shutter Speed - as I was in AV and had told it to set to 200, maybe I should have gone to Manual on the Camera.
Robert - I had the Gary Fong on - wonder if I should have overpowered the flash head by a bit more (+3 perhaps)
Yep, CT's on the same page as me. Everyone stop trying to figure it out and do it cos it just works :D
KIM, the shutter speed doesn't affect the flash which is a much faster burst. If you were using the Fong then I think you were trying to bounce the flash from the high ceiling. You would have been better shooting with the naked flash head.
K I M. Your flash has a maximum output that it can do. You usually know when it used all it has as the flash is bright and takes longer to recharge :)
Having just looked at guide numbers for a refresher.... If your flashgun has a guide number of say 40 then for a standard lens, direct flash (no diffuser) the aperture at 100 iso for subjects 5 meters away would be 40 divided by 5 = f8.
As the flash decides how much light to punch (using ETTL) you can choose any aperture wider than f8 too. Shut down more than f8 to say f11 and the flash does not have enough power and the shot will be under lit.
Caveat: The wine hasn't quite worn off yet ;)
Shut down more than f8 to say f11 and the flash does not have enough power and the shot will be under lit.
Caveat: The wine hasn't quite worn off yet ;)
why when you make the aperture smaller will the flash not have enough power?
cider hasnt quite worn off yet either! ;)
Keltic Ice Man
24-06-2007, 21:46
CT - So I gets my fluffy white polar bear, and white cat - lines them up in my room. Takes a reading at iso 200 of F2.8 and 1/8th. Then I switches on my flashgun - make sure its in ETTL point it to the ceiling (which is quite low) and Yep I get a well exposed shot!
So lets say that was a 7 year old kid instead of a polar bear would a shutter speed of 1/8th be enough or would there be motion blur on it?
PX18 - The Gary Fong was pointing straight towards the kids as the ceiling was a really long way up.
Robert P - :) Thanks
Janice,
Don't forget I was talking about using the flash at its maximum output. it can only give so much light. If you ignore shutter speed (cos it is fixed and not variable ie flash duration) the only way to control exposure is the aperture.
If you were stuck with say 1/1000th for an outdoor shot you don't have a choice of aperture unless the sun gets brighter.
need more wine my explanations are getting worse
CT - So I gets my fluffy white polar bear, and white cat - lines them up in my room. Takes a reading at iso 200 of F2.8 and 1/8th. Then I switches on my flashgun - make sure its in ETTL point it to the ceiling (which is quite low) and Yep I get a well exposed shot!
There you go! :)
So lets say that was a 7 year old kid instead of a polar bear would a shutter speed of 1/8th be enough or would there be motion blur on it?
That depends really on the strength of the ambient room light, but 7 year old kids are notorious for not keeping still aren't they? Do the time honoured professional thing - take a few shots and chimp like ****! :D
Keltic Ice Man
24-06-2007, 21:59
If I have 2 or 3 lines of 7 year olds, f2.8 won't give enough DOF, if I open it to say f11 I seem to go over the Shutter speed of 200 that AV allows me with a flash on. Is there a way around this, or perhaps as Shutter don't seem to matter - DOF works differently?
So lets say that was a 7 year old kid instead of a polar bear would a shutter speed of 1/8th be enough or would there be motion blur on it?
PX18 - The Gary Fong was pointing straight towards the kids as the ceiling was a really long way up.
Re. Fong - the thing is designed for bounce flash, even pointing straight forward it will still chuck light in all directions as it's supposed to do that.
If you need to shoot a 7 year old and the metered reading is too slow you can either:
Up the ISO to increase shutter speed
Open the aperture to increase shutter speed
Increase the shutter speed and lose some of the light from the scene (the flash will use more power to compensate).
Or a bit of all 3 to find the balance, maybe another stop of ISO and a stop wider, etc.
Just think about that cheap compact we've all had where when light levels drop to a certain level, the flash comes on automatically at a default flash sync speed of 1/60 or faster. The assumption is made for you by the camera that the flash is going to be the main or only form of illumination. This is why these cameras produce those ghastly typical night out pics where the subjects look like frightened deer in the car headlights. Flash is very linear - it goes straight out from the camera - hits the subject - returns to the onboard camera sensor which deems the exposure correct and quenches the flash. The flash never reaches that dark background and the flash sync (shutter) speed was too quick for the camera to record any ambient light room detail.
You DSLR is a bit more sophisticated than that. If you choose a slow shutter speed it 'assumes' from the outset that the flash is going to be combined with ambient light. The normal camera metering system meters for the ambient room light, while the onboard flash sensor determines the flash exposure, but all the while calculating the best way to combine the two sources of light. In the main it works very well with minimum interference from us. ;)
Manual flash is fine in a studio situation, but it's the last thing you want to be doing at say a wedding - continually doing the guide no maths in your head to determine subject distance or aperture when you're under plenty of pressure anyway is no fun - I've done it and I don't miss it. :gag:
Modern flashguns are a bloody godsend, we just need to learn to trust them - most of the time anyway. :)
If I have 2 or 3 lines of 7 year olds, f2.8 won't give enough DOF, if I open it to say f11 I seem to go over the Shutter speed of 200 that AV allows me with a flash on. Is there a way around this, or perhaps as Shutter don't seem to matter - DOF works differently?
You close down to f11 KIM, you don't open up from f2.8, so closing down to f11 would actually result in a slower shutter speed - not a faster one.
Keltic Ice Man
24-06-2007, 22:21
You close down to f11 KIM, you don't open up from f2.8, so closing down to f11 would actually result in a slower shutter speed - not a faster one.
So you do :D - long day I think; what is the slowest shutter speed you could hand hold with a flash, with say a 24 - 70 on a cropped sensor?
So you do :D - long day I think; what is the slowest shutter speed you could hand hold with a flash, with say a 24 - 70 on a cropped sensor?
The hand holding rules stay much the same - or it's safest to treat them that way. If you're using say a 50mm lens and a shutter speed of anything much less (slower) than that then there's a real danger if the ambient light is strong enough that you're not only going to get secondary ambient light images from possible subject movement, but you're almost certain to get them from camera shake.
You can prove all this to yourself with a few test shots in just the same way you took your polar bear shot earlier. :)
EDIT
sorry mate, so with a 24 to 70 zoom you should really match your minimum safe shutter speed to whatever focal length the lens is zoomed to if you're hand holding - 1/24 at the short end up to 1/70 at the long end. Far better to use a tripod really if you can.
antonroland
25-06-2007, 08:23
:D You guys make my head hurt!!
:lol: :bonk:
Kev - If I had dropped the Aperture - with 2 lines of kids I wouldn't have had enough DOF would I?
I Couldn't drop the Shutter Speed - as I was in AV and had told it to set to 200, maybe I should have gone to Manual on the Camera.
Depends on what your focal length was and how far away the kids were. I suspect you could have gone bigger on the aperture with the right combination. If you've got a nifty fifty type lens and shoot at F1.7 for a close up on the face you know you'll get a really shallow DOF but people use the same lens and aperture for doing full length shots at gigs where the DOF is sufficient for a full length person shot.
why when you make the aperture smaller will the flash not have enough power?
cider hasnt quite worn off yet either! ;)
You know how the shutter+aperture combination works for an exposure without flash don't you. When your not using flash the ambient light is there for the whole time of the exposure. The light from a flashgun is there from something between 1/1000-1/4000 depending on the output from the flash (unless we're talking about HSS which is a whole other thread). So given that the flash duration is so much shorter then the size of the aperture is what counts. Bigger the aperture the more effective the flash light is.
:D You guys make my head hurt!!
:lol: :bonk:
Its killing me too!! I dont see how I can make all those calculations every time I take a shot at a wedding! :eek:
Expose for the background: Outside, the background is going to be pretty light...... if I want to use F4 for a head shot but use flash to fill in shadows on that face......the shutter speed keeps flashing on the camera telling me it needs to be faster than the 1/250" that the camera will let me when there is a flash attached. So therefore it isnt exposed properly if it stops at 1/250" is it..when it actually needs to be faster......the resulting exposure of the background will be too bright.
antonroland
25-06-2007, 08:56
Janice would it help if I discussed shutter dragging flash photography with you now??:D :D :D
Janice would it help if I discussed shutter dragging flash photography with you now??:D :D :D
http://img40.imageshack.us/img40/3444/crazy1no.gif
I dont understand how I can have such a mental block about this when everyone else seems to understand it.
I'm not thick by any means..... but it just doesnt all fall into place. :(
Dont worry Janice, I dont understand it either :nuts:
Its killing me too!! I dont see how I can make all those calculations every time I take a shot at a wedding! :eek:
Expose for the background: Outside, the background is going to be pretty light...... if I want to use F4 for a head shot but use flash to fill in shadows on that face......the shutter speed keeps flashing on the camera telling me it needs to be faster than the 1/250" that the camera will let me when there is a flash attached. So therefore it isnt exposed properly if it stops at 1/250" is it..when it actually needs to be faster......the resulting exposure of the background will be too bright.
This is where High Speed Sync (HSS) is used.
1/250th is the X-sync speed which means it's the highest shutter speed where the entire sensor is exposed all at once. Higher speeds and the rear curtain follows behind the front curtain so only part of the sensor is exposed as the two curtains move across it.
HSS fires the flash in multiple bursts so that all of the sensor gets to see the flash as the two curtains move.
Just turn on HSS on your flash and you'll be able to select a faster shutter speed.
If you need to go faster than the normal sync speed janice then you have to turn HSS on. This will let you shoot faster speeds bit dramatically reduces the working distance of the flash.
Its killing me too!! I dont see how I can make all those calculations every time I take a shot at a wedding!
Expose for the background: Outside, the background is going to be pretty light...... if I want to use F4 for a head shot but use flash to fill in shadows on that face......the shutter speed keeps flashing on the camera telling me it needs to be faster than the 1/250" that the camera will let me when there is a flash attached. So therefore it isnt exposed properly if it stops at 1/250" is it..when it actually needs to be faster......the resulting exposure of the background will be too bright.
1.Increase the ISO? or ...
2.Stop down the lens? or...
3. A combination of both?
I don't think you're thick Janice, or anyone else having trouble with this for that matter, I know how difficult it is to get your head round this, but you're actually creating your own problem here by specifying f4 out of doors in what we are assuming is quite bright light.
The technically correct answer to this problem if you really want to use f4, is that here you really do need to switch the flash to Manual Mode - calculate the Guide No for the ISO you're using - divide 4 (f4) into the Guide No to give you the correct flash- to -subject distance to enable you to use f4 with the flash providing fill in on your subject. BUT you're absolutely tied to this distance - you're talking about a head shot, and at f4 it's likely to be quite a distance from your subject so you'll also need to consider which focal length lens you use to frame the shot as you'd like. Flash isn't an exact science either - that guide no is only a rough guide, you'll probably need to reduce power to get the result you want - those face shadows just lightly brightened - otherwise the shot can still look over-flashed. Pre digital togs used to spend a fortune on polaroid shots to get this right before they took the shots for real.
Just stop down a little, that's what I'd do, you get a bit more DOF but choose your backgrounds carefully which you should be doing anyway for the posed shots.
Hope that's helped a bit?
Just stop down a little, that's what I'd do, you get a bit more DOF but choose your backgrounds carefully which you should be doing anyway for the posed shots.
Hope that's helped a bit?
Now that has helped a lot, CT....thank you. I was trying to achieve something that wasnt easily achievable...thereby creating problems!
F11 outdoors for me then!! :thumbs:
Just a couple more things....
1. some people say "expose for the background"....i assume this means only the trees etc etc that are behind.....using MATRIX?
2. others say "expose for the ambient light".... this isnt the same as exposing for the background is it. ambient light includes your subject too doesnt it...so if your bride is in white..that alters the exposure completely.
3. if you expose for the background or ambient with the flash on your camera turned ON...wont the camera take into account that you have a flash and will be lighting with it and thereby give you not an ambient exposure but one which will include a zap of flash too?
1. some people say "expose for the background"....
2. others say "expose for the ambient light"....
3. if you expose for the background or ambient with the flash on your camera turned ON...wont the camera take into account that you have a flash and will be lighting with it and thereby give you not an ambient exposure but one which will include a zap of flash too?
1 and 2 are really the same thing - it's up to you to decide how much of the existing light you want to expose for - it could be a sunset behind the subject or just street lights in the background. Whatever it is the principal is the same, expose for that and the flash does the rest.
3: The camera doesn't take the flash into account when it meters a scene. The calculation for the flash exposure is only done when you fire the shutter. The flash then fires a low level burst which is used to determine how much power to use for a second burst - this all happens so quickly that is seems like only a single burst.
Just a couple more things....
1. some people say "expose for the background"....i assume this means only the trees etc etc that are behind.....using MATRIX?
2. others say "expose for the ambient light".... this isnt the same as exposing for the background is it. ambient light includes your subject too doesnt it...so if your bride is in white..that alters the exposure completely
Let's take a camera meter which just uses full frame average metering to try to understand these metering modes. All a full frame average meter does is mix all the tones in the scene projected onto your focusing screen down to 18% grey , which is just the same as metering on a grey card. I know you understand that you'd use this reading direct unless there were elements in the scene which were unusually light or dark, in which case you'd adjust exposure accordingly if those elements were important in the shot such as they patently would be with a white dress.
'Matrix' metering is actually a Nikon system, Canon's version is similar but is called 'Evaluative'. With these systems the screen is divided up into a number of different zones which are each metered independantly of each other, the camera software gathers the info and calculates what it considers to be the best exposure for all those different parts of the scene. It's a far more accurate system and I'd have no hesitation in using it for a wedding job. Just make sure that the white dress is included in the viewfinder, but plenty of the background too. I'm not saying you can trust the system completely in this situation you may still need to stop down a little after some judicious chimping. ;) I know lots of pros who simply use 'P' and auto flash for weddings, I've done so myself on occasions and you'd be surprised how well it works. Just keep an eye on that preview screen and adjust if you need to. :)
With regard to metering in Evaluative Mode, just meter the whole scene including your foreground figures.
3. if you expose for the background or ambient with the flash on your camera turned ON...wont the camera take into account that you have a flash and will be lighting with it and thereby give you not an ambient exposure but one which will include a zap of flash too?
LOL.Janice you're really thinking about this aren't you? :lol:
No it wont. You can set your mind at rest about this right now - take an ambient reading with the flash turned on and again with it turned off and you'll see that the meter reading doesn't change. When you take the shot the flash just provides the fill in for the ambient light settings - as long as you're using ETTL Mode on the flash.
Janice,
Here's an example of using High Speed Sync for fill flash.
First here's a shot without flash, I metered for the garden outside:
http://www.talkphotography.co.uk/gallery/data/500/no_flash.jpg
This next shot I used my 430ex is HSS mode everything else was the same:
http://www.talkphotography.co.uk/gallery/data/500/flash.jpg
Both shot were:
ISO 1600
1/800s
f/4
There's a slight difference in WB but I was in auto mode. HSS mode is ideal for the kind of shot you described because although the power of the flash is reduced you only need enough for fill light as you're not trying to light an entire scene with it.
I can't remember how you turn on HSS on the Sigma but I know it does support it...
Good example of Hi Speed Sync there from pxl8 which is another option for you. :thumbs:
The nice thing about HSS at least as far as the Canon 580 EX is concerned is that once it's set on the flash it stays set (but isn't used) even when you reduce shutter speed to normal sync speeds and engages again if you increase the shutter speed. You get a warning symbol 'Hi' at the bottom of the viewfinder when it's active.
Janice,
I don't think it has already been mentioned in this thread but the 'EOS flash bible' is a useful read. Check out part II - EOS flash modes and EOS flash confusion. There are also some useful tips at the end.
http://photonotes.org/articles/eos-flash/
Also check out the links here for good basic info to understand the whole flash thing http://photography-on-the.net/forum/showthread.php?t=138907
Ray
I can only thank you all again for being patient!
Im afraid its a rather bad character trait.... if I start to find out how something works before I use it.....I need to know it ALL!!
I cant just USE IT..... I have to be able to understand WHY it happens!!
I did want to use P mode with flash, CT, but with the Canons the shift mode in P is disabled when using flash so its 1/60" permanently... and no chance of changing aperture either. I thought that might be a bit restrictive.
I am going to be taking a million test shots throughout July then....with my lads at gunpoint one dressed in black and one in white (God help the one in the white dress! :D )
Thanks Rayfin. I actually have that article in my favourites from before.
For anyone else wanting to know more there is also THIS: http://www.planetneil.com/faq/flash-techniques.html
And thanks again all you patient people! :thumbs:
ranarama
25-06-2007, 20:05
I know I'm joining this late but thanks for all the good advice in this thread. It's filled in quite a few gaps in my understanding of flash techniques.
Keltic Ice Man
25-06-2007, 21:44
yep - gotta say thanks folks.
I'm sure like Janice there will be more questions on this soon. Got to try going outside and taking some pics for fill in now.
I might just throw one more thing into the mix, not to complicate things but because it may prove pertinent......
Flash exposure compensation is vital sometimes, especially if what you're shooting is predominantly white or black. If the scene is bright then the flash will underpower and make everything underexposed, if it's dark it will overpower and black things become grey.
I learn this the hard way from the couple of weddings I did last year, and it's proved helpful when shooting peoples houses too.
Generaly though, whatever I'm shooting, I tend to use matrix metering and then just let the flash sort itself out. Very rarely does it get it wrong!
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