D70 and SB-600 Underexposure

[alan_booker]

I'm using my D70 and SB-600 to take portraits - Flash to subject distance is about 6'. Flash mode is TTL. I have

the flash head at 45 degrees with an index card rubber banded to the head. I'm not getting underexposure warnings,

but the shots look pretty underexposed to me. How can I determine if my flash is working properly - is there some

sort of reference shot I can set up? Any other suggestions to get to this bottom of this would be appreciated.

[photo5]

I'd like to see an example. The Nikon flash metering iTTL on the D70 is pretty accurate. You don't get a look that shows you used flash much. I was faked out by this as well the first time I used my SB-600 with my D70s. It just looked under. But the Nikon iTTL flash metering is pretty accurate, and will look natural, not lit. Look for a catchlight in the eyes of your subject, and look for natural skin tones. You can dial in a +1 if you want more of a "flash look" in your photos, but it is working properly.

[elliot1]

I find that I generally have to have to adjust exposure compensation when bouncing flash regardless of which flash and camera combination I am using. I don't know if this is normal for everyone but it is for me. Many more factors come into play when using bounce flash that can affect the final exposure so photographer input may be crucial in getting a perfectly exposed bounce flash shot.

[tom_luongo1]

<em>"the shot looks pretty underexposed to me"</em>

<p>

I recommend learning to use the histogram. If it looks underexposed on the LCD, it may be an issue of ambient

light and or LCD brightness. The histogram will be more objective.

<p>

Another factor that might affect your image and exposure include whether your flash is zoomed in or out which

will affect the dispersion pattern of the flash. (Though your setup of a flash at 45 degrees with a card should

work pretty well)

<p>

I've always felt that Nikon's CLS tends to be biased towards underexposure to avoid blowing out highlights. It's

easier to recovery noisy shadows than lost highlights so it seems like a reasonable choice to me.

<p>

Also worth learning to use manual modes for flash and camera too.

[frank_skomial]

"whether your flash is zoomed in or out" - auto zoom if enabled does not work in titled position, and it gets retracted

to the widest setting, it flash is powered.

 

You do not tell what ISO you use, how tall and big is the room where you are trying to bounce, what aperture value

do you use? chances are that SB-600 just simply does not have the required power for your settings.

 

Then, did you pay attantion to flash under exposure warnings, just second after you took the picture? - read your

flash manual to find out how to make use of information that possibly the flash would provide to you.

[tom_luongo1]

Frank, I don't see anything in the SB-600 manual that says the power-zoom won't work if the flash is tilted. I

know that the SB-800 power-zoom does work even with tilt.

 

Possible reasons that the auto-zoom doesn't work for you would be 1) wide-angle diffuser is on, 2) the diffusion

dome is on, or 3) manual over ride is on

 

But the question of power zoom is not really relevant to original poster's question.

 

The query about a "reference shot" is a good one.

 

"How can I determine if my flash is working properly?" - begin by making exposures with a high shutter speed and

small aperture to minimize ambient light. Set flash exposure to manual. Vary flash power and compare

histograms. There should be a consistent trend from lighter to darker or darker to lighter depending on which

direction you varied the flash power.

 

The above is a necessary first step to checking out your flash before checking the TTL logic.

 

By the way, are you sure you have the camera exposure mode set to matrix metering? See what kind of results you

get when using spot metering with the spot selected on something equal to a gray card. (Caucasian face will

usual work well enough.) Or even place a gray card in the scene and spot meter off that

[egoldstein]

I use the D80 and an SB-600 in exactly the way you indicate and anywere from 45 - 75 degrees on the flash head tilt. You do not indicate whether or not you are using a diffuser of any sort. I use the Sto-fen and with this set up get excellent results nearly all the time. And yes, flash zoom does work when the head is tilted.

 

There are a couple of things: The images will be less "flash" looking and might only be appearing as under exposed when compared to the on-flash pictures.

 

Also, Keep in mind the angle of the flash head. If you get too close and keep the angle set to 45 degrees the bulk of your flash might be shooting right over the subjects head and bouncing off the ceiling behind them. When getting closer you can try shifting the flash head up a notch to bounce more light to come from directly overhead.

[alan_booker]

I uploaded some images. The camera distance to subject is about 54". I took a picture with my hand over the on camera flash to verify that there was no significant contribution by ambient light (the resulting picture was black). One picture is using the on camera flash. Another is the SB600 with the head at 90 degrees. The final picture is the SB600 at 45 degrees with a white card rubber banded to the head. No other diffuser was used.

 

Gallery URL

http://www.photo.net/photodb/member-photos?user_id=4361181

[tom_luongo1]

Try setting the White Balance to "Flash" instead of "Auto".

[alan_booker]

Insteresting idea - although my expectation would be that white balance would correct the relatively high color temperature of the flash, not basic exposure problems. Your experience is different?

[tom_luongo1]

Just rambling a little bit. I wouldn't really expect manual white balance to significantly affect the exposure. But it won't hurt.

 

Two of the sample shots were using CLS instead of pure TTL and would try to balance the ambient light with the SB-800. Nikon Viewer shows i-TTL in the EXIF and I think that's what that means. Make sure TTL shows on the flash control panel instead of TTL-BL.

 

The third sample shot was the on-camera flash and does look like it has more exposure.

 

The camera did a reasonable job of exposing here. Detail in the shadows can be brought up in post-processing while highlights (i.e. the blank wall) were preserved. You know you don't care about the blank wall but the camera can't always be sure.

 

In my experience, flash exposure is usually biased towards underexposure though not usually by this much. I post-process everything so it's never really bothered me.

 

By the way, there seems to be a bit of ignetting happening here. Make sure your flash head is zoomed out when bouncing though the issue might be the lens design. (It's something that would be obvious only on a blank wall and goes away at smaller apertures don't worry about it.)

 

Avoid those automatic modes. Try setting the camera to manual. 1/250 @ f/8. ISO 200. Flash set to TTL. (not TTL-BL)

[alan_booker]

Thanks, Tom

Good advice, all. I'm also working this issue with Nikon tech support, who had asked for sample images with one of the camera's automatic modes (So I recycled the images for this thread) I also post process most of my stuff and would rather have a little underexposure rather than blown highlights, but the sb600 behavior seems excessive to me. I was sure to have the flash on TTL (vs. TTL-BL) For any given situation, I could probably exposure comp my way to better images, but my basic goal is to find out if my SB-600 is at least working as designed.

[alan_booker]

Nikon tech support, based on the images, has suggested I send the gear in for evaluation. This should sort out equipment failure vs. user error. I'll post the determination to the thread

[robert_hohlfelder]

My D70 / SB600 combination tends to expose on the low side- not unlike the sample images posted above. I dial in some exposure compensation when needed.