Can someone tell me a technique for improving exposure when using an E-TTl strobe on emergency scenes. It seems that each time I'm shooting fires, wrecks, etc which involve reflective tape on bunker gear, the image is underexposed. Tried using a bracket to raise the flash with no luck. The best option so far has been to use a Vivitar 283 in automatic mode. It gives great results, but hate to carry two strobes in the bag. Any information would appreciated.

No suggestions for using TTL as it is not reliable.
Just say no to point and shoot and use manual.

k7xd wrote:
No suggestions for using TTL as it is not reliable.
Just say no to point and shoot and use manual.
Amen. Learn the flash and memorize the pertinent settings. It shortly becomes "automatic".

The reflective tape used on fire gear has the characteristic of reflecting light at nearly any angle.

Evaluative metering, the default mode for Canon flash, keys off the highlights which is why you are getting under-exposure. Try setting flash metering to "average" via CF.n (on the camera) which should produce results similar to the average metering auto sensor on the Vivitar.

Manual will be more consistent and predictable. With a bit of testing you'll be able to quickly determine the power levels needed at various distances. Stick with one f/stop and set flash zoom manually to a fixed setting such as 24mm so the only variable is power level.

But if you look on the back of the flash in M mode you will see there is an indicator which shows the distance at which flash exposure will be correct which takes into account aperture and flash zoom setting. All you need to do is estimate the distance and then turn the power dial until the indicator on the back of the flash is over that distance.

Chuck

It really makes you wonder how "Weegee" ever got by without E-TTL.

Or get a Metz 54 or 58 that can handle ETTL and Auto.

Carmen Miranda wrote:
It really makes you wonder how "Weegee" ever got by without E-TTL.

Carmen Miranda wrote:
It really makes you wonder how "Weegee" ever got by without E-TTL.


Did he have a choice?

Flash was indeed much simpler before zoom lenses and flashes, especially with negative film, if you were systematic and shot from fixed distances with memorized f/stops for each distance based on testing. Been there, done that....

But given the choice I use a tool that let me choose between manual and E-TTL as the situation required. I bet Weegee would too

Chuck

cgardner wrote:
But given the choice I use a tool that let me choose between manual and E-TTL as the situation required. I bet Weegee would too


Actually, it's quite likely he may have chosen Auto mode if there was reflective tape back in his day, as it would clearly be the superior mode in that situation. Assuming of course, that Canon was "progressive" enough to offer him the choice. Unfortunately Canon refuses to acknowledge that their E-TTL system has any limitations whatsoever. If there was one reason I'd consider switching systems it would be due to their flash system. So while I'm waiting for the 900 EXIII to show up, I guess I'll have to stick with my Metz or make the switch to Speed Graphic.

Good luck.

cgardner wrote:
Try setting flash metering to "average" via CF.n which should produce results similar to the average metering auto sensor on the Vivitar.
Chuck

Are you referring to CF.n 3 on the 580 EX flash?

This sets the flash in either ETTL or TTL. Option #0 is ETTL. Option #1 is TTL.

However, Canon's instructions are pretty clear about NOT using Option #1 for digital as that setting is intended ONLY for use with film cameras. Setting CF.n 3 to #1 will cause the flash either to misfire, fire at full output only, or not fire at all.

So ... I'm not sure what your recommendation actually is. Are you talking about a CF.n setting on the camera?

- Steve

No, he's talking about on the body. C.Fn 14 (on a 1D2) is ETTL II: Evaluative or Average.

bacilonur wrote:
No, he's talking about on the body. C.Fn 14 (on a 1D2) is ETTL II: Evaluative or Average.

Thanks....

Carmen Miranda wrote:
Unfortunately Canon refuses to acknowledge that their E-TTL system has any limitations whatsoever.


That's not true.. Wouldn't you consider completely changing it admission the previous system didn't work well?

Canon film cameras metered off the film during the actual exposure in a direct feedback loop. Canon called it "TTL". The move to digital sensors prevented that so the metering shifted to the viewfinder, with flash metered before the shutter opened via pre-flash.

The first iteration of digital metering was called "E-TTL" by Canon. It based flash metering around active AF points and had an "auto fill reduction" algorithm based on EV level which could be turned off via CF.n.

Canon completely changed the metering system again around 2004 with the 20D and later bodies moving from E-TTL to E-TTL II which compares ambient and pre-flash over 35 zones (more on pro bodies) and also uses focus distance information from most USM lenses (but only when flash is used directly).

One of the reasons I didn't jump into the DSLR game until the 20D arrived is negative feedback about how much the AF point based E-TTL sucked. The introduction of E-TTL II in the 20D appeared to solve most of those problems. But it wasn't until I wrapped my brain around how evaluative metering works that I figured out how to get good results with Canon E-TTL II: don't try to out think it. Point, shoot, evaluate, adjust.

Evaluative compares zones and finds the brightest ones, then decides whether they are specular reflections or areas of important detail. By comparing ambient light zone-to-zone which isn't affected by camera / subject distance with flash returns, which are affected by distance, the camera and create a rough 35 zone radar-like map of what is in the viewfinder.

So if using evaluative you can look in the viewfinder, spot the area of greatest flash reflection and know evaluative will err on the side of not blowing the highlights there. If that brightest area of reflectivity isn't closest to the camera and your intended center of interest your COI will wind up underexposed. But what you need to realize that correctly expose that middle-ground with any flash, manual or auto, you will only be able to to that by over-exposing the foreground which is equally undesirable.

So if anything using E-TTL II evaluative metering teaches you to compose flash shots more effectively, putting what is more important in the foreground ensuring better odds of correct exposure. But since it can't precisely meter the scene - there are only 35 large zones - some FEC adjustment will nearly always be necessary to make the exposure perfect.

The technical Albatross of DSLRs is the "R" the reflex mirror. Lose the mirror and use an Electronic Viewfinder instead and the sensor will dump and read the contents of the sensor 30-40 times per second or more. While its processing the data for the EVF it can also evaluate, down to the pixel level of detail, what areas are clipping. That's why some P&S cameras seem to do a better job of exposure control than a DSLR.

Live view? That's just Canon's way to start weaning still camera users away from optical. After all the video side of the house has lived with EVF since its inception. I have an EVF on my Minolta D7Hi and given the choice between an APS-C Canon with EVF and better metering vs what is offered now I'd take the EVF version in a heartbeat.

Chuck

Chuck: that's a really informative piece you've written above. Very helpful, interesting read. Thanks...

- Steve

Paratima wrote:
k7xd wrote:
No suggestions for using TTL as it is not reliable.
Just say no to point and shoot and use manual.
Amen. Learn the flash and memorize the pertinent settings. It shortly becomes "automatic".
Is this DPR? it would be nice if people would help others not with sarcastic remarks like the above..people of all abilities come here for this very reason..

Thanks for everyone’s response. Tried average metering through the custom function with positive results. That was definitely a step in the right direction.