Flash overexposing both foreground and background

Good afternoon.
This is my first participation here as I joined the forum some minutes ago.
My main subjects are landscapes, cityscapes and low light photography. Therefore, I am not an expert shooting people, specially using flash.
I shoot both with a D200 and D300, always choosing manual mode.
Using my SB-800 as a fill flash to photograph people, sometimes, I end up with both the main subject and the background heavily overexposed!
An example: last weekend I took a portrait of my wife against a bright cityscape. Of course, I used the flash as a fill-in. Here´s what I did: took a reading of the light using spot metering, to the brightest point of the background, making sure that the flash was turned off; adjust the speed as suggested by the meter to 1/4000, f/4 to get a nice bockeh, ISO 200; switch to matrix, turn on the flash (setting it to - 1EV) and lock exposure on my wife´s face; re-framed (always pressing the AE lock and fired. Result: both the main subject and the background were severely overexposed!
Following, I took the same picture under aperture priority, but at f/9 and the result was acceptable.
Question to you, experts: what am I doing wrong? How can I take photos in M mode, therefore choosing the aperture I want but getting the righ exposure?
Thanks for your help.

[zona5101]

Welcome!
humm...

took a reading of the light using spot metering, to the brightest point of the background, making sure that the flash was turned off; adjust the speed as suggested by the meter to 1/4000, f/4 to get a nice bockeh, ISO 200;

I don't know that you need to spot meter, an average or matrix reading should be fine. btw, Does your flash sync at 1/4000?

switch to matrix, turn on the flash (setting it to - 1EV) and lock exposure on my wife´s face;

??? You already set the exposure at 1/4000 and f4

re-framed (always pressing the AE lock and fired. Result: both the main subject and the background were severely overexposed!

I would say the brightest spot you metered for was significantly brighter than the rest of the scene.

Following, I took the same picture under aperture priority, but at f/9 and the result was acceptable.

Where did the shutter speed end up? (trying to figure out how many stops off you were from the first exposure to the second)

Question to you, experts: what am I doing wrong? How can I take photos in M mode, therefore choosing the aperture I want but getting the right exposure?

You are on the right track but meter the scene using an average or matrix reading or use spot but just understand what it is telling you and adjust accordingly. You'll need to adjust your shutter speed to a setting that is within your flash sync speed. (I don't recall what the hi-speed sync is for Nikon but I do believe to get there you have to set you flash to high speed sync mode). Then you can add your flash exposure by determining your flash to subject range & cooresponding f-stop. I believe the ttl will shut down the exposure when it thinks it's had enough light. That may or may not be the case and you would have to adjust from there.

.

[OsmosisStudios]

Originally Posted by Rui Lopes

adjust the speed as suggested by the meter to 1/4000, f/4 to get a nice bockeh, ISO 200; switch to matrix, turn on the flash (setting it to - 1EV) and lock exposure on my wife´s face; re-framed (always pressing the AE lock and fired. Result: both the main subject and the background were severely overexposed!

WHen you put the flash on the hotshoe and turn it on, the body should have automatically dropped the shutter speed from 1/4000 (WTF?) to 1/250 (which is the flash sync speed).

It would have also probably kept the f/4 aperture.

What that means is that you're now 4 stops over on the background. And your flash was still trying to fire (pretty strong) so it blew out your background.

Simple: Stop down the aperture.

[i speak in math]

Keeping the ISO at 100, the shutter speed and aperture effect the ambient light. Closing the aperture down will cut down on the light. Longer shutter will increase the light.

Keeping the ISO at 100, only the aperture effects the flash. Open the aperture up and more light gets in. Close it down and less light gets in.

The trick is learning how to control both to get a nice portrait.

1. Put the flash in manual mode.
2. Change to Av mode. Set the aperture to f/4.
3. Set your camera to meter in matrix mode to get a good reading of the scene.
4. Dial in -1~-1.5 EV stops on the camera to underexpose the scene.
5. If your shutter speed is above the sync speed (canon is 1/250th) you will need to up the aperture to get the shutter speed under that unless you want to use HSS.
6. Set the flash to 1/8th power and give it a shot.

The background should not be overexposed, but the flash on the subject might be a little dark or too bright. Adjust the power up or down until it matches nicely with the scene. You don't want to blast the subject, but want it to look natural.

Thanks for all your help!

Originally Posted by zona5101

Welcome!
humm...

I don't know that you need to spot meter, an average or matrix reading should be fine. btw, Does your flash sync at 1/4000?

??? You already set the exposure at 1/4000 and f4


I would say the brightest spot you metered for was significantly brighter than the rest of the scene.

Where did the shutter speed end up? (trying to figure out how many stops off you were from the first exposure to the second)


You are on the right track but meter the scene using an average or matrix reading or use spot but just understand what it is telling you and adjust accordingly. You'll need to adjust your shutter speed to a setting that is within your flash sync speed. (I don't recall what the hi-speed sync is for Nikon but I do believe to get there you have to set you flash to high speed sync mode). Then you can add your flash exposure by determining your flash to subject range & cooresponding f-stop. I believe the ttl will shut down the exposure when it thinks it's had enough light. That may or may not be the case and you would have to adjust from there.

.

Actually, now I can see that you are right. It doesn´t make sense to spot meter a whole background scene...
Now the flash-sync speed... the D300 defaults to 1/320. However, yesterday I read the instructions book again and find out the way to adjust it to any shutter spped till 1/8000!
Of course I am aware that the more the speed raises up, the lesser effectiveness may be expected from the flash. Currently, I am not aware of the speed used by the camera on that 2nd shot but, later at home I´ll take a look. I guess that given the overall light conditions and the fact that the sync flash was limited to 1/320, that was the used shutter speed, at f/9.

Originally Posted by OsmosisStudios

WHen you put the flash on the hotshoe and turn it on, the body should have automatically dropped the shutter speed from 1/4000 (WTF?) to 1/250 (which is the flash sync speed).

It would have also probably kept the f/4 aperture.

What that means is that you're now 4 stops over on the background. And your flash was still trying to fire (pretty strong) so it blew out your background.

Simple: Stop down the aperture.

Yes, but in that case I wouldn´t get the DOF I was trying to achieve... (f/4). I assume that the way to go is to raise up the flash syncro speed so I will able to shoot with such large aperture nrs.

Originally Posted by i speak in math

Keeping the ISO at 100, the shutter speed and aperture effect the ambient light. Closing the aperture down will cut down on the light. Longer shutter will increase the light.

Keeping the ISO at 100, only the aperture effects the flash. Open the aperture up and more light gets in. Close it down and less light gets in.

The trick is learning how to control both to get a nice portrait.

1. Put the flash in manual mode.
2. Change to Av mode. Set the aperture to f/4.
3. Set your camera to meter in matrix mode to get a good reading of the scene.
4. Dial in -1~-1.5 EV stops on the camera to underexpose the scene.
5. If your shutter speed is above the sync speed (canon is 1/250th) you will need to up the aperture to get the shutter speed under that unless you want to use HSS.
6. Set the flash to 1/8th power and give it a shot.

The background should not be overexposed, but the flash on the subject might be a little dark or too bright. Adjust the power up or down until it matches nicely with the scene. You don't want to blast the subject, but want it to look natural.

Also a good point. I still need to learn how to use the flash in manual mode. In #2 when you say Av I assume that you mean aperture priority as per Canon´s standards, right?
Aso, I understood that the trick is to reduce the burst of the flash either dialing in -1 or 1.5 stops and set the flash power to 1/8, assuming that I keep the max. sync speed. But, what to do if I manage to adjust the sync flash speed to HSS?
Again, thanks for all your help.
Rui

[i speak in math]

Originally Posted by Rui Lopes

Thanks for all your help!
Also a good point. I still need to learn how to use the flash in manual mode. In #2 when you say Av I assume that you mean aperture priority as per Canon´s standards, right?
Aso, I understood that the trick is to reduce the burst of the flash either dialing in -1 or 1.5 stops and set the flash power to 1/8, assuming that I keep the max. sync speed. But, what to do if I manage to adjust the sync flash speed to HSS?
Again, thanks for all your help.
Rui

Yes, aperture priority -- though if you meter correctly and are comfortable, manual mode is fine. Also, if your flash is on manual mode, there is no ttl. That means, no setting EV's or HSS. Just adjust the power up and down which controls the actual flash duration.

[OsmosisStudios]

Originally Posted by Rui Lopes

Yes, but in that case I wouldn´t get the DOF I was trying to achieve... (f/4). I assume that the way to go is to raise up the flash syncro speed so I will able to shoot with such large aperture nrs.

You can't just raise the flash sync speed: it's a hard limit in the camera. You may be able to use the HSS function (High Speed Sync) but thats generally only off-camera. The other option is to use a ND filter in front of the lens to lower the overall exposure.

[Benji]

It is in reading postings like this that I am SO glad I am not attempting to learn how to use a DSLR and I never will. Mine is set at manual 100% of the time when shooting for clients and I NEVER allow it to think for me, I think for myself. If I am out photographing someone and while looking at the scene I discover that the background is too bright, I don't start thinking about HSS or spot metering, I simply move the subject to where the background is dark. If the lighting isn't good I either move them to where the lighting is good, or I use a reflector. Occasionally I will add some fill flash if needed. Pose the subject and make sure the lighting is good, meter the bright side of the subject's face, set those readings into the camera, shoot a gray card, make the capture.

Benji

[i speak in math]

Originally Posted by Benji

It is in reading postings like this that I am SO glad I am not attempting to learn how to use a DSLR and I never will. Mine is set at manual 100% of the time when shooting for clients and I NEVER allow it to think for me, I think for myself. If I am out photographing someone and while looking at the scene I discover that the background is too bright, I don't start thinking about HSS or spot metering, I simply move the subject to where the background is dark. If the lighting isn't good I either move them to where the lighting is good, or I use a reflector. Occasionally I will add some fill flash if needed. Pose the subject and make sure the lighting is good, meter the bright side of the subject's face, set those readings into the camera, shoot a gray card, make the capture.

Benji

You'll never improve if you keep doing the same thing over and over again.

Originally Posted by i speak in math

You'll never improve if you keep doing the same thing over and over again.

Agree! The recent years brought us a huge bunch of new useful technologies, allowing to improve and get better and better results. A good example of what digital brought to us was the ability of shooting in almost any light conditions allowing the camera to "work for us" choosing the appropriate ISO... another one - the stabilization features, either VR from Nikon or IS from Canon, and many many others, allowing us to shoot for example at 1/13s with focal lenghts like 200mm! And much more. Of course, I agree that the photographer is the most important in all the process, always trying to choose the more adequated conditions to achieve his needs. But, why not learn how to ease life using what technology was made for ?
Again, many thanks for all the input and help from you guys!
Rui