TTL Compatibility?!?

[jen_b]

Hi, sorry if this is a dumb question, but I'm really confused about ttl, s-ttl, e-ttl...
As a new diver I would like a set-up that is ttl capable. I was looking at the Canon housing for my G11, but I read that the housing is not ttl capable, and the Ikelite one is, but only with Ikelite strobes? Is there any way to have e/s-ttl with the Canon housing and the Inon s2000 strobe? Someone said that maybe through fiber optic cables? Could anybody clear this up for me, I'd really appreciate it!

 

[M_Bipartitus]

First a clarification, most serious Canon cameras can operate in manual, TTL, or e-TTL modes. E-TTL is likely to give the best results in most Canon cameras as Canon has spent the most time developing this part of their flash algorithms. The ikelite housing will have a connector that mounts to the top of the camera where you would normally add a flash topside. When used with Ikelite DS strobes, the flash exposure will be automatically set using canon's e-TTL metering. The advantage is that metering is optimal, but the disadvantage can be fewer options in strobes and problems if there is a leak or broken wire.

The Canon housing has no connectors for strobes. However, some strobes can be used with an optical trigger (fiberoptic or slave sensor) if the internal flash is turned on. Strobes with optical sensors can be TTL or manual. The TTL strobes typically rely on matching the duration of the built-in flash (Inon calls this sTTL, but the camera should be in standard TTL mode). The G11 fires it's internal flash and stops the flash (quenching is the common term) as soon as the G11 detects enough light in the photograph. If your strobes are also flashing with the internal flash, you achieve TTL strobe metering without a wire. There are some drawbacks to this method; for example, you should block the internal G11 flash from shooting forward or you can still get backscatter. The lack of a wire or connector is considered a feature by some, as there are fewer parts to break.

If a Canon is in e-TTL mode and an optical trigger is used for strobes you can experience problems. In e-TTL, the camera will send one one or more pre-flashes to get an estimate of the needed flash duration during the actual photo. These pre-flashes can confuse optical triggers, though many have settings to try to get around this problem.

I personally use Ikelite strobes wired to a dSLR, so I don't have personal experience with the G11 or Inon strobes.

 

[randini]

In a nutshell, TTL means through the lens. The different varieties of TTL (iTTL, eTTL, sTTL, etc.) are just manufacturer specific flavors using different protocols. In all of them, essentially a light sensor (usually the one inside the camera) measures the amount of light entering "through the lens" and determines how long to keep the strobe on for and when to shut the it off. There are 2 ways to get TTL: electronically and optically.

In electronic you ave an actual cable that connects the camera's hotshoe to the strobe. In this setup you will need an appropriate TTL converter for the camera to communicate in the same language as the strobe (i.e. Canon camera to Inon strobe). In the ikelite solution you mention, Ikelite includes the appropriate circuitry in their housings so that they allow the camera to communicate with Ikelite strobes.

In optical, the camera controls the built in flash, and an external strobe basically copies what it "sees". The beauty of this is that the strobe only needs is to be able to "see" the light coming out of the camera's flash making it an ideal solution for transparent housings. A fiber optic cable is almost always recommended in this case to avoid misfiring of the external strobe by other light sources in the environment and to allow you to block off the light coming from the camera's flash to your subject (this will reduce backscatter).

Will the G11 in the canon housing work in TTL with the Inon S2000? yes. The canon housing is clear so the light coming from the camera's flash will be seen outside of the housing. Just get a fiber optic cord with the strobe, and attach it accordingly and you will get TTL when you have it setup appropriately. I'm not familiar with the G11 or the S2000 so I can't comment on what settings will work.

 

[scottfiji]

yes,

the S2000 will work great with the G11 + canon housing via Inon's S-TTL, also known as "optical" ttl.

You connect one end of a fiber optic cable to the strobe, and the other end to the housing so it "sees" the internal flash go off.

You can also try it without a fiber optic cable, the S2000 doesn't require one.

FYI, The S-TTL feature will only work when the G11 is in auto, Av, or Sv mode - not manual mode.

hope this helps,
Scott

 

[jen_b]

Thank you so much everyone- you have been such a great help!!

 

[Dashrynn]

FYI, The S-TTL feature will only work when the G11 is in auto, Av, or Sv mode - not manual mode.

hope this helps,
Scott

will it shoot s-ttl in program mode? what about custom? Im hoping that you forgot to mention that but then again im sure you meant what you meant.

 

[scottfiji]

will it shoot s-ttl in program mode? what about custom? Im hoping that you forgot to mention that but then again im sure you meant what you meant.

yes, it works in program mode also, but please don't use program mode use Av mode

Custom mode- I would think so, unless your "custom shooting mode" is set to manual mode.

 

[coralcruiser]

I switched over to the G10 this fall and bought the Inon S-2000 to go with it.

I took the camera to Fiji last month and decided to leave the strobe home because I wanted to get the "feel" of the camera. Unfortunately I learned that using a strobe with this camera is an absolute must!!

Reading through this thread has been quite helpful as I head off to Lembeh next month.