Got TTL?

[Jamdiver]

Ron, tell us how you REALLY feel! Love the dead horse beater. I think we need to get some gloves and you and f3 can go a few rounds underwater. We'll shoot it in manual flash and iTTL and see which one produces the better images.

And i'll be the promoter :14::14::14:, all proceeds to the 'Buy Jam new toys fund'.
I've got a Don King wig and everything :rofl2: :rofl2:

 

[RonFrank]

Well, I apologize if my post was over the top.

The irony is that I don't use iTTL UW!

I'd love an UW shootout. Just fly me to YAP! I could go head to head with Mike V, and enjoy loosing VERY much!

 

[rjsimp]

Well, I apologize if my post was over the top.

The irony is that I don't use iTTL UW!

I'd love an UW shootout. Just fly me to YAP! I could go head to head with Mike V, and enjoy loosing VERY much!

Yeap.. Ron.. But its the PRINCIPLE of it Dangit!

 

[Fastmarc]

Ok, I apologize in advance for this very novice question, but I just can't seem to find the answers else where.
What is TTL really? What does it stand for and what does it do?

 

[rjsimp]

TTL means Through the Lense I believe.. correct me if I am wrong someone.

 

[Fastmarc]

TTL means Through the Lense I believe.. correct me if I am wrong someone.

Ok, so does it judge the flash intensity via the lense and automatically set it?

 

[rjsimp]

Marc,

Yeap in a basic sense.. It measures the amount of light coming through the lense and then adjusts the intensity of the flash or shuts off the flash when it has enough light to expose the shot.

 

[RonFrank]

TTL = Through the Lens. Ironically people have so accepted the in camera exposure meter (that uses TTL metering) and autofocusing (that uses TTL areas) that most just say TTL and assume one is talking about flash metering.

There are two types of metering done in TTL mode on a DSLR. TTL exposure metering sets the shutter in A mode, Aperture is S mode, everything in program mode, and provides an exposure scale in manual mode. This metering is known by different names for each manufacture, like 3D color matrix metering II for Nikon.

Flash TTL. uses the same CCD as the 3D color matrix metering along with a dedicated flash sensor for flash. Flash TTL does a couple things in addition to determining the exposure value. It calculates the exposure, and then determines the amount of flash needed.

There has been a lot of discussion on this subject. For whatever reason some people feel very strongly against flash TTL. Ironically similar discussions were being done in the 70's~80's when people who used hand held meters did not like in camera TTL meters for setting the camera exposure. Ironically ambiant hand held meters have an advantage over reflective meters for many situations so at least those folks had a real argument.

Now, very few even seem to be aware of hand held meters, or what the advantages of using them may be, but they sure feel strongly against UW flash TTL!

 

[Fastmarc]

Hmm....
Thanks for the explanation Ron & Rich.

 

[f3nikon]

Well, I apologize if my post was over the top.

The irony is that I don't use iTTL UW!

I'd love an UW shootout. Just fly me to YAP! I could go head to head with Mike V, and enjoy loosing VERY much!

First of all it’s nice to see that ol Ron is back on his medication. For a complete answer one needs to address the key difference between TTL FLASH control for Film and iTTL FLASH control for digital SLRs as stated by one of ol Ron’s blind followers:

“measures the amount of light coming through the lense”

The KEY question is HOW does the camera measure the amount of light?

With the TTL system of Film cameras the light is measured by a photo sensor that is pointed at the Film itself. This is the most accurate way of measuring the light striking the Film and REFLECTED to a SENSOR because the camera is receiving the light intensity data from the actual Film itself, REAL-TIME FEEDBACK. This is what ol Ron and his blind followers are putting down as “old technology” of the Film age because of dim witted comments like this:

“I guess inovation and improvement in technology is not worth the engineer's time if they choose not to implement it the same way as the old technology?”

Fast forward to the Digital age…Nikon, Canon and the rest of camera makers would LOVE to have used the TTL system (old technology) from their Film Cameras. The system works very well, simple design and is somewhat predictable. The only problem is the recording media, a CCD sensor in digital cameras (was film in film cameras) does NOT REFLECT the light hitting its surface the same way as it did for film! This is the “brickwall” I spoke about.

So it’s on to plan “B”, since they cannot measure the light hitting the recording media in REALTIME, another way but not as accurate, is to place the photo sensor in the viewfinder area. Not as accurate as the TTL sensor pointing at the recording media as with film because this "new high tech system" does not provide real-time measurements and the circuitry much more complicated, Nikon calls this iTTL.

Complicated… because now the system has to fire a PREFLASH to determine the amount of flash power to use, before firing a PRESET main flash power level!

With the sensor in the viewfinder a PREFLASH FROM the STROBE is fired at the subject, the light reflected off the subject makes its way back to the camera, Through The Lens of the camera, hitting the reflex mirror which is then bounced up towards the viewfinder where the light sensor is located waiting to sense the light intensity data.

The light intensity data is then feed into the camera’s electronics where it is processed and sends out a MAIN FLASH level command to a MATCHED…. NIKON DESIGN…Nikon SB-800 Flash head! This is why the Nikon DSLR and the Nikon SB-800 flash works well together.

Now due to ol Ron’s total incompetence in U/W photography or photography in general, he ASSUMES that Nikon or Canon gave the details on the workings of their “proprietary” iTTL circuitry and software to the Aftermarket U/W strobe makers or even if they had access to the design, decide not to use it, because of this incoherent statement:

“If you think that Ike iTTL is somehow magic, I'd love to hear that explaination. I'm not sure if it uses preflash or not, but my guess, yes. Why would it not?”

I am in the camp of Nikon and Canon keeping their proprietary iTTL systems design, a secret from each other and everyone else, which now leaves the Aftermarket U/W strobe makers holding the BAG! Because without the design plans the strobe makers will have a difficult time in figuring out how much and how long a PREFLASH to fire and also have to redesign their strobes to communicate with Nikon or Canon’s power commands to the strobes. This could also leave the door wide open for Nikon or Canon to manufacture their line of U/W iTTL strobes in the future, like the Nikonos line (103 or 105) from Nikon.

Or the Aftermarket U/W strobe makers decide NOT to use the Nikon or Canon iTTL systems altogether because it is just too complicated a design and produce a “work around” or “band-aid” design. And that design is to BY-PASS the photo sensor located inside the camera and install their own remote external sensor in their “TTL controller or converter” which has to be purchased separately.

So now the task of the STROBE firing a PRE-FLASH is taken out of the picture completely! The AM U/W strobe makers are free use to their NON PRE-FLASH firing… NON-NIKON SB-800 strobe!

One little “minor” problem with NOT using the TTL or iTTL sensor INSIDE the camera and placing their own sensor OUTSIDE the camera’s lens is that the system is now:

NOT iThrough The Lens or Through The Lens!

Their system should be called Through The External Controller! I’ll explain the differences on my next post.

Their system is in fact an “Automatic” flash exposure system like my $50 Vivitar 285HV land strobe!

A very interesting write up from one of the AM U/W strobe makers:

“This Sea & Sea TTL Converter allows TTL exposure control when connected to Sea & Sea housings for Nikon digital SLR cameras with Sea & Sea YS strobes. The converter allows quick switching underwater between TTL mode and manual mode from outside the camera.

You can use the TTL correction dial after checking the results of a shot in the LCD monitor to adjust the amount of strobe light for the next shot. Because the converter comes with two separate strobe connectors, you can use advanced automatic TTL flash adjustment with two strobes. “

Does not say anything about firing a PRE-FLASH for iTTL but it uses the term “TTL” rather loosely! A Jr. lawyer can do a number on that one in court. And this statement:

“You can use the TTL correction dial after checking the results of a shot in the LCD monitor to adjust the amount of strobe light for the next shot.”

Checking the LCD monitor???? Isn’t this like shooting in MANUAL?????

So are you sure you are using iTTL or any type of TTL???