Things that can go wrong

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Archive 2010 · Things that can go wrong

Zenon Char
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p.1 #1 · Things that can go wrong

I have posted a few threads on lighting preparing for a few weddings. I've been doing night shots outdoors, indoor shots, outdoor in overcast (on Saturday) in full manual, AV mixing up putting the flash on ETTL and Manual. I'm even setting color temperatures for the light conditions. I'm getting planned, repeatable results which is my goal.

Today was sunny and warm so I decided to go out start checking out fill flash. I had no people but you can work work objects. I would do two shots, one without flash and one with. Every flash shot I took was nuclear. A person would have gone blind.

So I got home and for hours I'm trying to figure out what went wrong. Finally I got it. I was in AV and when I metered my shutter speed was at 1/640 with the flash off. Then the second shot which lit the city was at 1/200. In DPP it does not show if I had HSS on or off but I can only predict it was off. It had to have been on off. The only reason I am posting this is I don't recall seeing the meter change but it must have. It should have correct? I took about 20 sets of images and they were all the same. Maybe I was not paying attention because I had the first exposure set.

I'm glad this happened. Good to make these mistakes now. Anyway I'm going to go out tomorrow again.

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Feb 09, 2010 at 03:08 AM

BrianO
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p.1 #2 · Things that can go wrong

Zenon Char wrote: Today was sunny and warm so I decided to go out start checking out fill flash. I had no people but you can work work objects. I would do two shots, one without flash and one with. Every flash shot I took was nuclear. A person would have gone blind.

What metering mode were you using? (Matrix, center-weighted, etc.)

Zenon Char wrote: ...So I got home and for hours I'm trying to figure out what went wrong. Finally I got it. I was in AV and when I metered my shutter speed was at 1/640 with the flash off. Then the second shot which lit the city was at 1/200. In DPP it does not show if I had HSS on or off but I can only predict it was off.

Yes, it was probably off, so the camera defaulted to the max sync speed of 1/200. If you didn't change the aperture that would result in overexposure.

For fill flash outdoors or in large spaces one trick that will help is to set the meter for the smallest area your camera is capable of, center the subject in the frame, and press the FEL (flash exposure lock) button. The camera will fire a metering flash and lock it in, then you can recompose to put your subject wherever in the frame you want him or her, and when you take the shot the flash will fire with the predetermined power, rather than trying to light up whatever is now in the center of the frame.

I also usually dial in -1/3 to -1/2 FEC (flash exposure compensation) when shooting outdoors, because I think it gives a more natural, less "flashed" look to people pictures.

BTW, with High Speed Sync, you can leave it on and if your shutter speed is at or below sync speed it will fire normally, only going into HSS mode if your shutter speed goes over sync.

Feb 09, 2010 at 04:59 AM

Zenon Char
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p.1 #3 · Things that can go wrong

BrianO wrote:
Zenon Char wrote: Today was sunny and warm so I decided to go out start checking out fill flash. I had no people but you can work work objects. I would do two shots, one without flash and one with. Every flash shot I took was nuclear. A person would have gone blind.

What metering mode were you using? (Matrix, center-weighted, etc.)

Spot for this one but I use both evaluative (matrix) or center.

Zenon Char wrote: ...So I got home and for hours I'm trying to figure out what went wrong. Finally I got it. I was in AV and when I metered my shutter speed was at 1/640 with the flash off. Then the second shot which lit the city was at 1/200. In DPP it does not show if I had HSS on or off but I can only predict it was off.

Yes, it was probably off, so the camera defaulted to the max sync speed of 1/200. If you didn't change the aperture that would result in overexposure.

For fill flash outdoors or in large spaces one trick that will help is to set the meter for the smallest area your camera is capable of, center the subject in the frame, and press the FEL (flash exposure lock) button. The camera will fire a metering flash and lock it in, then you can recompose to put your subject wherever in the frame you want him or her, and when you take the shot the flash will fire with the predetermined power, rather than trying to light up whatever is now in the center of the frame.

I'll give the FEL a try.

I also usually dial in -1/3 to -1/2 FEC (flash exposure compensation) when shooting outdoors, because I think it gives a more natural, less "flashed" look to people pictures.

When I did my weekend test and todays I did have it set between -1 and -2 but I'll try - 1/2 as well.

BTW, with High Speed Sync, you can leave it on and if your shutter speed is at or below sync speed it will fire normally, only going into HSS mode if your shutter speed goes over sync.

Feb 09, 2010 at 05:26 AM

cgardner
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p.1 #4 · Things that can go wrong

You said the flash was "nuclear" but actually it was the ambient light at 1/200th which was the culprit in the over-exposure more than the flash.

As Brian suggests the best strategy for setting flash outdoors is to just leave it in high speed mode and let it switch as needed.

To avoid surprises in flash power when the flash slips into high speed mode use the camera in M mode not Av. That way you will know for certain whether you are below sync limit or not at all times. With all that snow correctly exposed highlights are a no brainer if you simply use the overexposure warning in the playback to tell you when and exactly where clipping is occurring in both the ambient background and the flash lit foreground.

What you did do ideally in the shots is shoot into the shadow side of the ambient. Flash can't reduce contrast if it overlaps sunlit highlights. But to avoid a flat look in the fill you need to raise the flash above the camera on a bracket. Its a perceptual thing. Because we see things lit from above most of the time we consider a downward angle / pattern to be more natural. The fill from the sky comes from overhead and to get a seamless match of natural and artificial you'll want the angles of both to be similar. Its particularly important in portraits for creating natural looking 3D shape on the face.

Feb 09, 2010 at 12:17 PM

Zenon Char
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p.1 #5 · Things that can go wrong

I use it in M mode when the flash is the main source. I put it in AV for fill flash. Without flash I always shoot in AV as it saves me using two adjustments to meter for ambient. I guess I'm a little lazy but I certainly have learned the benefits of manual in the last month. I recently purchased the RRS wedding bracket which I will use. I use all there plates and quick release clamps.

Well I'm going to head out to that post again today if it is sunny and try in both AV and M. All in prep to shoot people in about 6 weeks when everything warms up.

Feb 09, 2010 at 01:38 PM

Zenon Char
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p.1 #6 · Things that can go wrong

Sorry had to drive my wife to work. I did see that overexposure warning was blinking on other shots as well. I tried everything and nothing made sense. I powered the flash down to 1/128 in M, - 3 on ETTL. I should have been a little quicker on my feet. Today I'll take my sunglasses off

so I can see what I'm doing. Bright outdoor light bugs me. They will definitely be off for an important shoot. I'm glad this happened. Better now.

Feb 09, 2010 at 02:17 PM

cgardner
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p.1 #7 · Things that can go wrong

See my tutorial on high speed flash (click the WWW button).

What I've found with Canon evaluative metering for flash is that it expects the ambient highlights to be below clipping. That makes sense because if the ambient is already clipping the highlight then adding flash will clip them more.

Conventional wisdom for outdoor portraits when the subject's back is to the sun is the let the hair become a nuclear halo, but that's exactly what throws off the flash metering. What I do when shooting in Av mode with flash is use the OEW to get the ambient highlights below clipping first before adding flash which in backlight usually requires about -2 EC because exposing for the highlight detail on the backlight subject doesn't match what the metering algorithms are programmed to expect.

But once the ambient is reeling in below clipping with the minus 2 EC the flash evaluative flash metering performs quite brilliantly at the default FEC = 0 setting.

Something else not mentioned in the thread is ISO used. Outdoors in bright light you want to use ISO 100. Higher ISO make it more difficult to keep the ambient highlights below clipping.

Manual is always better when using flash outdoors because it eliminated the variable of the camera's control of the ambient part of the exposure mucking up the works. Sunlight is very consistent. Its really just as easy to put the camera in M, pick the f/stop desired for DOF, then adjust shutter speed to get the background below clipping. Its just a matter of turning a wheel, just as done with EC, to arrive at the same result.

When using high speed flash in Av mode its better to shoot at wider apertures due to the power drop. For example if shooting at f/11 in conventional mode flash range will be significantly reduced if you simply open a stop to f/8 and trigger the shift to high speed mode. Better to open to f/4 or f/2.8 where the drop in flash performance will be offset by the fact not much flash power is needed if shooting at f/2.8

Its just a matter of understanding how the different pieces of the exposure puzzle fit together.

Feb 09, 2010 at 05:50 PM

Zenon Char
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p.1 #8 · Things that can go wrong

Thanks. I just book marked your tutorial. I had better day today. Before I went out I checked my 5D2 C.Fn. In C.Fn 1.7 I had it on 2. 1/200 to 1/60 Auto. It is do to with low light. I put it back to 1: Auto before I went out. Not sure if that effected me yesterday but I more than likely did not have HSS on.

I shot in AV but will shoot in M next time. I started to post something but I found something interesting. If I don't do a pre fire will the camera adjust my shutter speed on it's own on AV? If it does this changes everything. Is this what you all have been trying to tell me? I did not change any settings except turn the flash on. Look a the changes in shutter speed. Only when I pre fired did it go lock to the ambient reading. I had it at ISO 100 and Spot Meter. I checked my focus point and it was consistent between shots.

By the way thanks for everyones help on this. I'm very grateful.

Without flash - 5.6 - shutter = 400

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With flash - 5.6 - shutter = 320 - no pre fire

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Second shot with flash - 5.6 = shutter = 500 no pre fire

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With flash - 5.6 - shutter = 400 with pre fire. I did a few in a row with pre fire and the shutter was consistent.

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Feb 09, 2010 at 11:03 PM

Zenon Char
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p.1 #9 · Things that can go wrong

You probably were wondering what I was talking about. I messed myself up and it was due to the focal length change and the flash. Separate issues. Even without the flash on, if I had been paying attention to the shutter speed between shots I would have seen the difference in shutter speeds.

Once I set up my first shot I never checked the second or third one. I thought because I was in spot it should have been the same but spot metering is not pin point and I was changing focal lengths due to lens creep while chimping. I have always known as soon as you move your camera over even a bit and press the shutter button the shutter speed changes.

Then I started wondering what was my camera was doing? I thought it was making adjustments on me during exposure. When I set up in AV and let's say it is F 5.6 and the shutter is 400 I never check to see if it recorded those numbers I had seen in the viewfinder. I just check the histogram. Viewing them at home I was expecting the shutter speeds to be the same and they were not so it threw me off.

Someone pointed out this NEVEC to me which probably did not help.

http://eosdoc.com/manuals/?q=NEVEC

Edited on Feb 11, 2010 at 06:14 AM · View previous versions

Feb 11, 2010 at 04:50 AM

rogie
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p.1 #10 · Things that can go wrong

BrianO wrote:
Zenon Char wrote: Today was sunny and warm so I decided to go out start checking out fill flash. I had no people but you can work work objects. I would do two shots, one without flash and one with. Every flash shot I took was nuclear. A person would have gone blind.

What metering mode were you using? (Matrix, center-weighted, etc.)

Zenon Char wrote: ...So I got home and for hours I'm trying to figure out what went wrong. Finally I got it. I was in AV and when I metered my shutter speed was at 1/640 with the flash off. Then the second shot which lit the city was at 1/200. In DPP it does not show if I had HSS on or off but I can only predict it was off.

Yes, it was probably off, so the camera defaulted to the max sync speed of 1/200. If you didn't change the aperture that would result in overexposure.

For fill flash outdoors or in large spaces one trick that will help is to set the meter for the smallest area your camera is capable of, center the subject in the frame, and press the FEL (flash exposure lock) button. The camera will fire a metering flash and lock it in, then you can recompose to put your subject wherever in the frame you want him or her, and when you take the shot the flash will fire with the predetermined power, rather than trying to light up whatever is now in the center of the frame.

I also usually dial in -1/3 to -1/2 FEC (flash exposure compensation) when shooting outdoors, because I think it gives a more natural, less "flashed" look to people pictures.

BTW, with High Speed Sync, you can leave it on and if your shutter speed is at or below sync speed it will fire normally, only going into HSS mode if your shutter speed goes over sync.
this was my concern in a previous post about hss only turning on after the camera has exceed max sync speed. also, what is the difference between the flash symbol with the H and the triangular arrows pointing right in hss mode? i have found that i am only able to achieve hss fp with the arrow symbols.

Feb 11, 2010 at 05:46 AM

BrianO
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p.1 #11 · Things that can go wrong

rogie wrote: ...what is the difference between the flash symbol with the H and the triangular arrows pointing right in hss mode? i have found that i am only able to achieve hss fp with the arrow symbols.

You should have HSS when the H symbol is lit. I don't know why it's not working for you.

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Feb 11, 2010 at 06:28 AM

rogie
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p.1 #12 · Things that can go wrong

BrianO wrote:
rogie wrote: ...what is the difference between the flash symbol with the H and the triangular arrows pointing right in hss mode? i have found that i am only able to achieve hss fp with the arrow symbols.

You should have HSS when the H symbol is lit. I don't know why it's not working for you.

i have my camera set to second curtain sync. is this why?

Feb 11, 2010 at 06:36 AM

BrianO
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p.1 #13 · Things that can go wrong

rogie wrote: i have my camera set to second curtain sync. is this why?

Yes. If the camera is set to 2nd curtain sync then the flash must also be set to 2nd curtain sync, because the camera won't be sending a first curtain sync signal.

(I always use 2nd curtain sync. At high shutter speeds it makes no difference, but at low shutter speeds any ghost trails will follow a moving subject naturally. So I just leave it on all the time so I don't have to remember to change it.)

Feb 11, 2010 at 06:46 AM

rogie
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p.1 #14 · Things that can go wrong

BrianO wrote:
rogie wrote: i have my camera set to second curtain sync. is this why?

Yes. If the camera is set to 2nd curtain sync then the flash must also be set to 2nd curtain sync, because the camera won't be sending a first curtain sync signal.

(I always use 2nd curtain sync. At high shutter speeds it makes no difference, but at low shutter speeds any ghost trails will follow a moving subject naturally. So I just leave it on all the time so I don't have to remember to change it.)
so in order to achieve the hss fp i must turn off second curtain sync in camera and switch flash to the H symbol? or does it still give the same hss fp with second curtain sync mode on flash but the only difference being that i might get ghosting trails at lower shutter speed. is this correct? the only differentiator between the two modes is the method of exposure?

Feb 11, 2010 at 07:43 AM

BrianO
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p.1 #15 · Things that can go wrong

rogie wrote: so in order to achieve the hss fp i must turn off second curtain sync in camera and switch flash to the H symbol?

You know, I've never tried using HSS and 2nd curtain sync at the same time. I don't know if it's possible or not. I suspect not.

rogie wrote: ...or does it still give the same hss fp with second curtain sync mode on flash but the only difference being that i might get ghosting trails at lower shutter speed.

When using high speed sync or any other "continuous" light source (including the sun) you won't get a sharp image plus ghost trails; you'll just get motion blur. That's because the subject will be equally lit in all positions.

Feb 11, 2010 at 07:53 AM

rogie
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p.1 #16 · Things that can go wrong

BrianO wrote:
rogie wrote: so in order to achieve the hss fp i must turn off second curtain sync in camera and switch flash to the H symbol?

You know, I've never tried using HSS and 2nd curtain sync at the same time. I don't know if it's possible or not. I suspect not.

rogie wrote: ...or does it still give the same hss fp with second curtain sync mode on flash but the only difference being that i might get ghosting trails at lower shutter speed.

When using high speed sync or any other "continuous" light source (including the sun) you won't get a sharp image plus ghost trails; you'll just get motion blur. That's because the subject will be equally lit in all positions.
according from what i was doing last night (experimenting with hss), i dont remember getting anything above 1/250th in hss mode with second curtain sync enabled on camera. ill check again tonight just to make sure when i get out of work.

Feb 11, 2010 at 07:58 AM

BrianO
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p.1 #17 · Things that can go wrong

rogie wrote: ...i dont remember getting anything above 1/250th in hss mode with second curtain sync enabled on camera. ill check again tonight just to make sure when i get out of work.

In order for both to be active, you'd need to see both the H icon and the triple-triangle icon at the same time.

I don't think that's possible.

Feb 11, 2010 at 08:09 AM

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p.1 #18 · Things that can go wrong

HSS and SCS are intrinsically incompatible. HSS works by repeatedly firing the flash in rapid succession while the curtains travel across the frame. As such, it is only effective for exposures faster than the x-sync speed. The HSS setting is ignored at or below x-sync.

SCS works by firing the flash just prior to the closure of the second curtain, rather than immediately after the opening of the first curtain. Thus it only applies to exposures slower than the x-sync speed, since if the shutter speed is faster, the second curtain has already begun to close before the first curtain has fully opened.

Feb 11, 2010 at 08:44 AM

BrianO
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p.1 #19 · Things that can go wrong

Feb 11, 2010 at 09:14 AM

wickerprints
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p.1 #20 · Things that can go wrong

wickerprints wrote: HSS and SCS are intrinsically incompatible.

...SCS works by firing the flash just prior to the closure of the second curtain, rather than immediately after the opening of the first curtain. Thus it only applies to exposures slower than the x-sync speed, since if the shutter speed is faster, the second curtain has already begun to close before the first curtain has fully opened.

BrianO wrote:
Why would that make HSS incompatible? HSS always works when the shutter curtains are chasing each other in a slit; that's the whole point of HSS. Even with first curtain sync, at any speed above normal sync the second curtain begins to close before the first curtain has fully opened.

If HSS didn't start firing until the first curtain was fully open -- which is what 1st-curtain sync does -- then you wouldn't get complete coverage of the frame at 1/500 to say nothing of 1/8000.

I'm not talking about HSS in that paragraph. I'm talking about SCS, and explaining why it cannot be implemented when the shutter speed is faster than x-sync. In such a case, the second curtain has already begun to close before the first curtain is fully open, which means there is no way to fire the flash once without causing uneven exposure. You could fire it multiple times as in HSS but then you can't call it SCS anymore, since in order to get even exposure, you are firing the flash before the first curtain has even had a chance to expose the entire frame.

My point is that HSS is unnecessary when slower than x-sync, and required faster than x-sync, whereas SCS can only occur slower than x-sync, and would result in uneven exposure when faster than x-sync. The two can't be combined in any meaningful way.

Feb 11, 2010 at 10:29 AM

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