Signposts in the Night with Underexposed Person

[Major Eazy]

I thought I am supposed to know how not to get this happening, yet it is happening. Am I becoming too rusty and forgotten the correct way to deal with it? Or is there something about the signposts themselves?

Say you and a friend are out at night-time, say you want to take a photo of your friend standing next to a signpost. Could be something like 'Welcome to Scotland' signpost by the road.

You would need to try to get a spot meter reading on the person, AE Lock on the person, and stuff like that, focus lock, reframe to include the signpost, then fire. Flash fired, but photo looked like signpost is bright, and readable, yet person is too dark. Have I missed a step?

I've very rarely done night photography, I did learnt some basics just in case one day I would want to do night photography, but I never got around to it, and forgotten those how-to-do-it stuff.

Or are modern signposts too strongly reflective and they fool the cameras into giving right exposure to the signpost yet still leave person in the dark?

 

[Kodiak Qc]

•
Yes they are! …as they are perceived as specular light in the frame.

 

[Major Eazy]

•
Yes they are! …as they are perceived as specular light in the frame.

So what can I do to cut down that too much light?

 

[Kodiak Qc]

Their effect is inversely proportional to the brightness of the rest of the
light meter read and their relative position to the centre of the light meter.

They are a pest! …only controllable through the angle of incidence.

 

[Major Eazy]

Well I did used spot metering away from the signpost, metering on person, lock AE and meter reading, then reframed.

And as for that "controllable through the angle of incidence", I assume you meant I shouldn't stand right slam bang in front of the signpost, just move myself aside and take the photo at an angle?

 

[Kodiak Qc]

Well I did used spot metering away from the signpost, metering on person, lock AE and meter reading, then reframed.

As you se, this did not help since your subject was less reflective…

And as for that "controllable through the angle of incidence", I assume you meant I shouldn't stand right slam bang in front of the signpost, just move myself aside and take the photo at an angle?

Where you stand is pretty much irrelevant, what is is where the light comes from!
So do not stand in the reflected light.

 

[Nionyn]

Most modern road signs contain a material which is designed to reflect most of the light hitting it right back where it came from. Like cats' eyes and the reflective material on high-vis jackets, this is to make them more obvious to drivers at night.
It sounds as though the 'signpost' giving you problems is of this type.

To test this shine a torch at the signpost. Look at how bright it is (i.e how much of the light it reflects back at you). Then get an assistant/small child/random stranger to shine the torch at the sign from some angle off to the side whilst you stay where you are.
Is there a marked difference in the apparent reflectivity of the sign? If so you are dealing with a sign of the material explained above.

If this is the case, as long as you keep the flash on or near the camera no amount of tweaking settings on camera or flash is going to help you. You're going to have to get the flash off the camera and away to the side somewhere.

 

[Cistron]

Well I did used spot metering away from the signpost, metering on person, lock AE and meter reading, then reframed.

And as for that "controllable through the angle of incidence", I assume you meant I shouldn't stand right slam bang in front of the signpost, just move myself aside and take the photo at an angle?

Your locked exposure is for the ambient (continuous) light. Of which, at night, obviously, there isn't much around. So I suspect your camera underexposed. Then your flash fired, which is an independent exposure. In TTL-mode, the camera recognised from the pre-flash that a lot of light is coming back in. Thus it likely set the flash output to its lowest setting, yet with a reflective sign that was still too high, but too low for the face.

There you have it, an underexposed face and an overexposed signpost.

If you want to photograph someone in front of a reflective sign at night, you'll have to get your flash off-axis. Though that might not work either, since signposts generally reflect light in several directions.

 

[Phil V]

Your locked exposure is for the ambient (continuous) light. Of which, at night, obviously, there isn't much around. So I suspect your camera underexposed. Then your flash fired, which is an independent exposure. In TTL-mode, the camera recognised from the pre-flash that a lot of light is coming back in. Thus it likely set the flash output to its lowest setting, yet with a reflective sign that was still too high, but too low for the face.

There you have it, an underexposed face and an overexposed signpost.

If you want to photograph someone in front of a reflective sign at night, you'll have to get your flash off-axis. Though that might not work either, since signposts generally reflect light in several directions.

This^
But as no-one has given the full story - there's 2 exposures to juggle*, but as flash is your main light source and static, my method would be.

Set the camera to Manual, eval/matrix metering and adjust for about 1 stop underexposed. This will give you some detail in the background, you might want to go to maybe -2/3.

Get the flash in Manual mode and off camera, use a start point of 1/4 power and adjust from there using the histogram and rear screen to judge if you don't have a light meter.

If the sign is still too bright, move the flash and subject further away from it, using the Inverse Square Law to lessen the amount of light falling on the sign.

You can change the angle and position of the flash in relation to the sign but keep the relationship to your subject the same to alter the ratio without needing to change settings (if that makes sense).

*The usual story is 2 exposures, but you've thrown a spanner in the works with an additional subject that has a really odd relationship with reflected light, it's do-able but you have to understand the parameters you're juggling.

 

[Major Eazy]

Thanks guys, I'll have to consider setting up off-axis flash.

Food for thoughts, would covering up the flash head with something to softer the light, such as tissue or diffuser, help out a little?

 

[Cistron]

Food for thoughts, would covering up the flash head with something to softer the light, such as tissue or diffuser, help out a little?

Nope, unfortunately, it doesn't work this way. You'd have to increase the (apparent) size of your light-source to make it softer - that means either you chose a big modifier (softbox, umbrella, ...), or you move it closer. Though with a speedlight, just moving it closer won't have much of an effect, unless you are photographing ants.

Adding tissue or one of the diffuser cap just increases the throw of the light. If there is nothing for the light to bounce off (such as a white ceiling or floor), this won't change your shot at all.

 

[Phil V]

Thanks guys, I'll have to consider setting up off-axis flash.

Food for thoughts, would covering up the flash head with something to softer the light, such as tissue or diffuser, help out a little?

See the thread below this (lighting a couple?), it's a common misconception that you can somehow change the whole effect of a flash with power or a small diffuser - it's all about relative size.

 

[Kodiak Qc]

would covering up the flash head with something to softer the light, such as tissue or diffuser, help out a little?

•
Light is light. The reflective surface is what it is…
It will be the same s**t… just a different pile.