More details on overexposure problems using TTL (Olympus E-M1)

[morretti]

I have been perplexed by problems of dramatic overexposure using TTL with my Olympus E-M1 and Sea & Sea YS-01 strobes. (One YS-01 is 3.5 years old; the other was new in summer of 2014). I posted a query about this issue back in August, see http://www.scubaboard.com/forums/ol...rexposure-problem-using-ttl-olympus-e-m1.html

I had only one week of diving with this set-up last summer, so now that I’m back home, I have been experimenting with various shutter speeds and aperture settings.

I set the camera on M, used the 60mm lens, and took numerous shots of a small wooden carving from a couple feet away. The room was mostly dark, so the lighting for the shots was supplied almost entirely by the strobes (it was dark enough that for most shots I had to use the Sola focus light to lock focus).

I varied aperture setting from 6.3 up to f22. I varied shutter speed from as low as 1/40^th to as fast as 1/320^th. The ISO was 200. I did the shot with just the older (left) strobe, then just the new (right) strobe, and then with both strobes.

Do these results suggest that the YS-01 strobes just aren’t working well with the OM-D cameras, at least for TTL? Should I consider different strobes, or am I doing something wrong? (I know that more experienced diver/photographers will suggest abandoning TTL entirely, but I would like to have the TTL working before I try relying on manual, especially when there are shots that I don’t get a second chance with).

Here are two patterns from numerous shots: (when I say “overexposed,” I mean way way overexposed):

1. With the EM-1 and a single strobe, regardless of shutter speed, overexposure sets in at apertures of F11, F13, and more narrow.
   1. almost every shot at F10 was OK
   2. At F11, the exposure with a single strobe was OK about half the time and way overexposed about half the time.
   3. At F13, there were four shots that were OK, but 14 that were overexposed.
   4. At F14 and narrower, the shots were consistently overexposed (though there was one solitary F14 shot that was OK).
   5. The results with a single strobe differed somewhat depending on whether I used only the 3-year-old strobe or just the brand new strobe—I haven’t tried to analyze that difference.
2. When I tried the same settings using both strobes, the results were consistently better than using a single strobe, but overexposure was evident more than half the time at apertures of F16 and narrower.
   1. At F11 and F13, using both strobes, there were no overexposed shots, even though a single strobe at these settings produced dramatic overexposure at least half the time.
   2. At F14, with both strobes, one out of four shots were overexposed
   3. At F16, using both strobes, almost every shot was good
   4. At F18, using both strobes, almost every shot was overexposed
   5. At F20, using both strobes, about half the shots were overexposed

At F22, using both strobes, all the shots were overexposed

I'm having trouble figuring out how to post photos, but if this works, the following is a pair of examples so you can see the difference between the OK shots and the overexposed ones:

this photo was 125^th at F18, with both strobes firing:

This photo was at 125^th at F14, with both strobes firing:

I still have an Olympus OM-D E-M5, so I tried the same setup with that camera. Although I didn’t do as many variations, it appears that the E-M5 did better.

1. For example, with a single strobe, the exposures at F11, F13, and F14 were all good, in contrast to the E-M1, which caused overexposure half the time at F11; most of the time at F13, and almost all the time at F14 and smaller.
2. At F18 and F20, using both strobes, the shots with the E-M5 appeared to be consistently good, while the E-M1 caused the strobes to overexposure more than half the shots with the same settings

I really like the EM-1. Do I need different strobes if I want to keep trying with TTL?

 

[victor]

Remember I am no expert I really do recommend a course you will see significant improvments in all aspects of your underwater photography not just your exposure issue.

I suggest you try the same experement using the camera in Manual.
You will be surprised at how forgiving the systems are when operating in this mode. I know I was surprised.
I go for a higher F Stop to improve depth of field.
But set speed to 1/125 or 1/160, mid F stop on your lens, get very close, and test different powers on your strobes to see what works best.
This will work in many cases.
Having different types of strobes both switched on and TTL may never be compatible if they fire at slightly different times. It seems quite likely that if one fires before the other then the second may never fire or if it does it will overexpose the picture.
E.g. if the TTL was satisfied by strobe 1 then firing strobe 2 will overexpose the frame.

 

[orenbvip]

Trying to use and figure out TTL is a waste of time just go Manuel and in the long run you will be way better off. Start at some known all around settings : example f8 1/125 and play around.

 

[oszillodrom]

I have a similar setup. I concur that you will end up going manual (on the camera and the strobes) anyway. I get better results that way, and it doesn't take a lot of practice to get used to it.

 

[jd950]

While I agree that there are advantages to shooting in manual mode, I can understand the desire to have the rig work in ttl as it is supposed to and the OPs problem would irritate me. FWIW I use the same camera and housing with Inon strobes and do not have these issues and actually can usually get quite acceptable results from ttl. I think the problem is communication between the camera and the strobes. I have read before of S&S strobes not playing well with olympus cameras.

Two points to consider: The results in water may be different and you may want to be careful about overheating the strobes using them out of the water.

If you would like to meet in Denver and try out my Inons in a pool with your camera (maybe A1 scuba?) I would be happy to meet you and let you use them for some test shots.

 

[bvanant]

I believe that there is a well known issue with the EM-1 and TTL. If the subject is light (tan, white, etc.) , there are all sorts of trouble with the EM-1 and TTL using the internal flash. More to come when we get back from PNG.
Bill

 

[morretti]

bvanant: I'll be interested in your thoughts when you are back from PNG. thanks much

 

[Foxtrot16]

Trying to use and figure out TTL is a waste of time just go Manuel and in the long run you will be way better off. Start at some known all around settings : example f8 1/125 and play around.

+1 on that, learn how to use your strobes with manual settings and you will get better results.

Plus it also allows you to play around / adjust each strobe to different settings so you can get different results.

I have the EM-5 with twin S&S YS110A strobes and essentially I set my F stop and shutter speed and then adjust the strobes manually to get the result I am after. This means I can position my strobes in any position and adjust each one of the separately to give me the lighting I am after - for example I may have one strobe to the side and one from the top so the top one is usually less power than the one from the side etc.

Karl