Overexposure problem using TTL (Olympus E-M1)

[morretti]

Jack: i'm not sure that the shutter-speed theory works to explain all the issues above.

The fifth photo in the original post was shot at 1/160th f6.3, and the exposure was ok. I'll try to post a bigger shot of it here. (Well, posting a larger photo didn't work).


So the very next shot (the 6th in the original post) was also at 1/160 and f6.3, but it is way overexposed:

I reacted to that overexposure by drastically stopping down the camera, so the very next shot after that, of the same scene as the 6th photo, was shot at 1/320th and f 13.0.

This is disappointing news to hear that the problem might be the YS-01 strobes in combination with the EM-1 and TTL. (I was hoping that the diagnosis might be that I had mistakenly set the flash setting on the camera to full instead of fill). If it's the strobes, do you think I'd be able to replicate the issue here at home, far from the ocean?

 

[orenbvip]

TTL is junk just go manual.

 

[Incident]

TTL is junk just go manual.

Agreed, but thought I would give a few reasons why TTL isn't ideal.

First, TTL is based on the camera deciding when the scene is well exposed, based on a not so small number of variables. Keep in mind, the camera is deciding when a scene is well exposed, not correctly exposed, and that is a key and critical difference.

Here is an example:
If you have a scene and you are using center weighted metering, and shooting an image that has a fairly medium to slightly dark blue (say Zone III or IV, for our photo students) subject in the center, and a rather bright (white sand, light rocks, etc. around the frame, say zone VIII), and then you are using TTL, here is what will happen.

The camera will be trying to get a good exposure on the area of the image that falls within the center metering pattern. In this example, the camera will overexpose the blue subject by blasting the subject with light from the strobes (it's trying to get the blue subject from Zone III to Zone V). It will also end up cooking the surrounding white sand and over expose that way beyond any chance of saving the image (will move from zone VIII to blown out zone X).

TTL is simply doing what the camera is programmed to do, which is get whatever it is metering to reproduce on the sensor or film as an average tone (Zone V).


By contrast, using manual strobe settings, you can dial in the amount of light to make the image look the way you want it to look (dead on exposed, slightly under/over, etc.). It is fast and easy and leaves you in control over the final image.

Hope this helps.

 

[Wisnu]

one more disadvantage of TTL - it drain your battery fast.

 

[orenbvip]

Once get the hang of manuel i hardly ever change the power settings that much and just play with the A and F. It's a lot easier than one would think. Start by setting at 3/4 power on each strobe and then a F and A setting that is a good starting point say F10/12 and 1/250th or 1/160th.

 

[KeithG]

one more disadvantage of TTL - it drain your battery fast.

Can you explain your opinion? I am here to learn!

I have learned (or been re-taught) the following concepts by this thread:
a) if you are using manual camera settings and attempting TTL flash, then make sure you set your camera to under expose under ambient conditions. Duh! otherwise the addition of extra light from the flash can only over expose your shot. Not sure how much you need to under expose and/or how well this strategy works with different camera / strobe combos.. You may have to grossly under expose. No idea.
b) some camera / strobe combos "may" (will!?) not work very well under certain edge conditions. Or maybe never. Under any conditions. I have some strobes (S&S ys110) whose optical trigger is very suspect and inconsistent.
c) using manual strobe settings guarantees a consistent strobe response (hence the calls for "go manual" when thinking strobe settings).

I started out using totally auto camera and TTL strobe settings. This worked excellent for 90% of my early pictures. As I progressed I ventured more and more into that 10% zone where nothing worked. I now use 100% manual camera and wired manual strobes. Everything is my fault.

 

[Wisnu]

with TTL, the camera will measure he ambient light, and then the internal flash will iluminate the subject with the amount of light for proper exposure (according to the camera algorithm) can be 1/2, 3/4 or full power. The sTTL strobe then will mimic it.
with manual, you set your internal flash to minimum power ( I normaly set at 1/64 power) just sufficient to trigger the strobe - and YOU (not the camera) who control the amount of light. If you set the strobe to 75% power, it will consistently iluminate the subject at 75% power; suficient or not, it depend on you - you can add or reduce as you wish - or you can play with the aperture what ecer you like.
Seem a bit daunting - but with practice you will realize how easy.

 

[Interceptor121]

with TTL, the camera will measure he ambient light, and then the internal flash will iluminate the subject with the amount of light for proper exposure (according to the camera algorithm) can be 1/2, 3/4 or full power. The sTTL strobe then will mimic it.
with manual, you set your internal flash to minimum power ( I normaly set at 1/64 power) just sufficient to trigger the strobe - and YOU (not the camera) who control the amount of light. If you set the strobe to 75% power, it will consistently iluminate the subject at 75% power; suficient or not, it depend on you - you can add or reduce as you wish - or you can play with the aperture what ecer you like.
Seem a bit daunting - but with practice you will realize how easy.

I agree with Wisnu that putting the flash at minimum power in manual is the best for the battery with sea and sea and TTL does suck battery
however I also have to say that with a a camera that does not have a manual flash option and always shoots TTL I get plenty of shots with my two Z240 in virtue of the superior implementation of the advanced cancel circuit of inon strobes
I have also to say that a macro and super macro you need very little light even at small aperture so the camera battery should not be a problem and you should need to recharge your strobes by the time the camera battery is dead anyway

 

[R-balljunkie]

i found the S&S TTL was all over the place, overexposure on lots of shots. ended up shooting in manual.
Switched to Inon d-2000's and the TTL is spot on 95% of the time.