Consistent Overexposure with EOS Rebel Cameras & Speedlite Flash

[AnnieO]

I have a Canon T6i - use Auto mode- with flash bracket, shoe cord and a canon Speedlite. All is fine then in September it started to overexpose the photo - not every one but many at the event. then I read on a forum that it happens with Canon Speedlites - I then got a Neewer flash, and two Godox flashes - same issues. All in TTL setting. I then got the Canon T8i - and same issues. Then I tried new shoe cords - same issue. Tried not using the flash bracket - same issue - then I tried the new camera and a different lens - same issue. I am at the end of my experiments and cannot figure the issues. Please help - I have many events coming up and need this to work. I have asked so many people and no one can seem to help. I changed batteries, I used the rechargable battery for one of the Godox. All the same issues HELP

[deebatman316]

Does the Canon lens also cause the overexposure too.

-Demetrius

EF 16-35mm F/2.8L III USM, EF 24-70mm F/2.8L II USM, EF 28-135mm F/3.5-5.6 IS USM, EF 50 F/1.8 STM & EF 70-200mm F/2.8L IS III USM

EOS 40D & 5D Mark IV

430EX III-RT & 600EX II-RT

[AnnieO]

These three were this past Monday - Canon T8i in Auto Mode, Canon lens 18-55 and with flash bracket and flash was Godox TT685II

[barnesfoto]

So it looks like we have four pages of "what camera/lens/setting are you using?" but no solutions. 

I am having same issues while teaching a HS photography class, and both Canon and Godox flashes are overxposing shots with camera on Manual and flash on TTL.  As there is not a solution in the entire thread, my solution is to ditch the Canons and use Nikons. The Nikon flash system does not seem to randomnly overexpose. 

[Da5idC]

Thanks for that comment - very frustrating to have no-one with anything close to a solution.

With the hope that someone will still see this thread, I've had the same problem - exposure is OK for a few shots then suddenly overexposes completely.

Last time it happened I was shooting on a 5dmk4, manual mode, ISO 1250, 1/200 at f2.8, evaluative metering, lens Canon 50mm f1.2,  flash 600EX2-RT on E-TTL, no compensation, on second curtain sync. First two OK, next three blown out. Interestingly, on all five the EXIF data shows under flash "Did not fire, compulsory mode" - also on the two that were correctly exposed.

This also happens n my 7Dmk 2 though I can't be bothered to go into my backups to find some examples. The only difference I can think of is that the 7D is usually on center weighted metering.

I am hoping for some solutions this time, regards, DC

[Nick2020]

First of all, ETTL is a good starting point, but some adjustments might need to be made to take into account the size of the room, ambient light, the reflectivity of the surroundings, and so on. A white room is going to be more reflective than one with dark walls, so using flash exposure compensation might help. 

On our flashes, that can be done by pressing the SET button and turning the dial to the plus or minus side. It might help to start with -1 and bounce the flash off the ceiling. Then do additional tests and adjust as needed. 

Note too that it takes the flash longer to refresh than the shutter. You'll know when a Canon flash is ready to fire at full intensity again when the pilot light on the flash turns red. If the light is green then the flash won't fire at the intensity suggested by ETTL or whatever manual flash settings you've selected. 

Lastly, when you are in the auto mode or the Program mode, the camera considers the flash to be the main light source. This means that the ambient light in the scene is viewed by the camera as secondary light, and the exposure is set based on the flash output. As a result you might see a properly exposed subject but an under-or over exposed background in some cases. Flash exposure compensation can help here, as I suggested earlier. 

When shooting in the AV, TV or M mode, the ambient light is the main source used for exposure and the flash merely supplements the ambient light. This should give you a better exposure for the background, but it might require some finessing to get your subject illuminated to your preference.

Setting the flash to manual output would give you more control. Full output is 1/1. Depending on the situation, you can decrease the output to a lower fraction and make incremental adjustments until you are happy with the results.