YN-468 II sometimes overexposes on TTL (D3200)

[damjanev]

<p>Hello,</p>

<p>I have been using this flash on my D3200 for a while and found that it sometimes overexposes in TTL mode. It does not happen always, but i have seen some washed out flash photos. I analyzed the issue for a while:</p>

<ul>

<li>It always overexposes by same amount. At first i thought that when the issue appears, the flash fires at full power. I tried to simulate this by setting the ISO to 3200 or 6400 and expecting a nuked image. This didn't happen. The image was "consistently" overexposed.</li>

<li>It only tends to overexpose when using direct flash. Bouncing the flash seems to give consistent and proper flash exposure.</li>

<li>The issue seems to be independent of the ISO, shutter speed and aperture settings on the camera, as well as the focal length of the lens and the respective zoom position of the flash head. Rear curtain flash also doesn't influence the issue.</li>

<li>The flash output at different power settings (on manual) is good and consistent.<br />With both camera and flash in manual mode, i have been able to get consistent exposure of the same scene in several (~10) consecutive shots. All single shots, couple of seconds apart. Then i repeated the test with raising the ISO and lowering the flash output power by 1 stop. The exposure was the same on all test shots. Camera settings were 1/200 (sync speed of the D3200) and f/8.</li>

<li>The issue seems to be independent of the camera metering modes as well. Do camera metering modes matter in TTL flash exposure at all?</li>

<li>It seems like setting exposure compensation on the flash to -1 gives consistently underexposed images (by 1 stop). I didn't made enough test shots to positively conclude this. Interesting thing is that -1/3 and -2/3 exposure compensation on the flash seems to have no influence on the final image exposure. All other settings (-3 to -1 and +1/2 to +3) look OK. Again, not enough test shots were made to conclude this.</li>

</ul>

<p>Has anyone else noticed such behavior? Has anyone been able to fix the issue?<br>

Sending the flash to Youngnuo in Hong Kong under warranty is probably going to cost too much time and money.</p>

<p>Regards<br />Damjan</p>

 

[CvhKaar]

<p>Hi Damjan,<br>

Do you have examples of overexposed pic ?<br>

Often under/over exposure whith many flashes is scene and metering dependand.<br>

For instance, when using matrix metering and having a dark backround , or a distand background will often result in overexposure of a closeby- or lighter ( as in more reflecting ambient light) subject. In these cases center weighted or spot metering works better for the subject but will result in a dark or black background when using only one flash.. ( just an example, many situations possible...).<br>

This then is not a defect of the flash or camera, but just plain physics determining wath is possible in a given situation using given equipment...<br>

So it is hard to say without seeing examples wath is going on, but from your description it sounds that the flash and camera may be perfectly ok..</p>

 

[damjanev]

<p>Unfortunately i deleted all the samples. I will make test shots again and post samples.</p>

<p> </p>

[rodeo_joe1]

<p>"It only tends to overexpose when using direct flash. Bouncing the flash seems to give consistent and proper flash exposure." - Then I'd suggest not using ugly direct flash. Really the only excuse for using direct flash is for fill with other light sources, or if you're a paparazzo that doesn't care at all about lighting quality.</p>

<p>The reason for the overexposure could be simple 'subject failure'. Sometimes direct flash leaves the background almost totally dark, and if you have a small bright subject in the middle of the frame surrounded by blackness, then you're obviously going to get overexposure because the camera's metering will be fooled.</p>

[damjanev]

<blockquote>

<p>The reason for the overexposure could be simple 'subject failure'. Sometimes direct flash leaves the background almost totally dark, and if you have a small bright subject in the middle of the frame surrounded by blackness, then you're obviously going to get overexposure because the camera's metering will be fooled.</p>

</blockquote>

<p>It might be the case, but it makes me wonder why this overexposure is not consistent and why does it not appear on every shot. if it appears on every directly flashed shot it's predictable and correctable with exposure compensation. Could it be that subtle differences in the scene fool the metering differently? Do camera metering modes (matrix, center-weighted, spot) matter in iTTL?<br>

The test scene consisted of: part of a couch (red-brick colored velvetish material), some pillows (white-ish :-) ) and some white wall behind. Test shots were handheld, so some shots may have more of the white wall. I will try to make new test shots using a tripod, taking care that the scene stays the same each time. I will throw in the plastic diffuser in the test cases as well.<br>

And, as you already suggested, i mainly do bounced flash when using TTL on camera and using direct only as fill. That is why i hardly notice the issue. This whole discussion is aimed at establishing whether my camera and/or my flash are somewhat defective or incompatible.</p>

 

[CvhKaar]

<p> Do camera metering modes (matrix, center-weighted, spot) matter in iTTL?</p>

<p>Yes they do, and they often are the reason for unexpected results because they tell you what part of the picture needs extra light from your flash and how much..</p>

[rodeo_joe1]

<p>The metering modes are exactly the same for ambient or flash exposures. That's why i-TTL needs to set off a pre-flash.... errr, flash, so that the camera's metering system can use it to set the power of the real flash. (Most time and energy inefficient system ever IMHO!)</p>

<p>Spot metering will almost certainly cause inconsistent flash exposures, and I'm not too happy with Nikon's current version of Matrix metering either. Try Centre-Weighted average.</p>

[damjanev]

<p>Sample shots. Having another look at the images on the computer screen, the overexposure looks like 2+ stops.</p>

<ul>

<li>Camera on a tripod</li>

<li>Triggered via remote</li>

<li>ISO 400, F/8, 1/200, flash on TTL</li>

</ul>

<p>Direct flash</p><div></div>

[damjanev]

<p>Direct flash - overexposed</p>

<div></div>

[damjanev]

<p>Direct flash with diffusor</p><div></div>

[damjanev]

<p>Direct flash with diffusor - overexposed</p><div></div>

[damjanev]

<p>Bounced flash</p><div></div>

[damjanev]

<p>Bounced flash with diffusor</p><div></div>