topic Re: Speed light underexposed. in Speedlite Flashes

Speedlite 430EX II & Speedlite 600EX-RT underexposed.

rrnkp — Sat, 03 Jun 2023 13:01:19 GMT

Hi, I have 430 EXII and a 600 EX. On my t6i both flashes set to E TTL work properly in all modes auto, program and manual, with the exception of the exposure confirmation lite on the 600 EX. It does not illuminate.

Now the weird part when I use either flash,E TtTL, on the the 70d both flash are under exposing but the exposure confirmation light flashes on the 600 EX, meaning it was properly exposed. Either I have to go +3 on exposure compensation or manual 1/1 for the pics to come out properly. This occurs in all modes auto, program and manual.

I'm photographing dimly lit parking lots/ streets at all distances. Both cameras have 18-135 Canon lens.
I’ve tried the Canon 18-55 and 50mm f1.8 on the 70d still under exposed.
Any ideas on what’s going on?

Re: Speed light underexposed.

rs-eos — Fri, 02 Jun 2023 21:33:37 GMT

I'm trying to follow... are you saying you have two camers (T6i and a 70D) and with the same exact two flashes, you're seeing differences?

First thing to rule out... are the flashes in the same positions in both of your scenarios?

Also, is there a possibility that during the setup with 70D, that one of the flashes was able to "see" the other one? When all flashes are in E-TTL and they "see" each other, that will affect the amount of power chosen for the flashes.

Re: Speed light underexposed.

deebatman316 — Fri, 02 Jun 2023 21:44:34 GMT

First of all how are you using these speedlites. Are the speedlites fully recharged when this happens. To clarify you are using the 600EX not the 600EX-RT or 600EX II-RT. Please clarify each issue with BOTH cameras. Its hard to follow along how you're describing the problem.

Re: Speed light underexposed.

Anonymous — Fri, 02 Jun 2023 22:29:59 GMT

Is it possible that you have external flash settings (flash exposure compensation) set in the 70D that might be overriding the FEC in the flashes themselves?

Re: Speed light underexposed.

deebatman316 — Fri, 02 Jun 2023 23:03:24 GMT

When FEC is set on the speedlite it overrides the camera body's setting. Regardless of which one has more or less FEC dialed in. Also FEC doesn't work in Full Auto so there are more things going on. We need to know the "big picture".

Re: Speed light underexposed.

Anonymous — Fri, 02 Jun 2023 22:38:47 GMT

I tested with my 5D IV and a 600EX-RT, and if the flash has zero FEC, and the camera has -1 set in the external flash menu, the camera will change the flash FEC to -1 with a half press of the shutter button. So, I disagree that that could not happen. The camera can override the flash FEC,

Re: Speed light underexposed.

deebatman316 — Fri, 02 Jun 2023 23:02:42 GMT

Just as I said. If the speedlite already has FEC dialed in (ie NOT set to 0 FEC) and you set FEC in the camera. The speedlite overrides the camera body's FEC. Also that's if the speedlite is set to 0 FEC and you add for instance +1 FEC. The camera body's FEC will be applied. If there isn't already FEC dialed in on the speedlite. If the speedlite has +1 FEC dialed in and you dial in -2 FEC in the camera the speedlite's FEC is used and the camera's is ignored it's in the manual.

Re: Speed light underexposed.

Anonymous — Fri, 02 Jun 2023 22:47:16 GMT

But if he doesn't realize that he has FEC set in the 70D camera, it would explain his problem with the 70D. His T6i may have zero FEC set in the camera, so it works as expected. See my point?

Re: Speed light underexposed.

deebatman316 — Fri, 02 Jun 2023 22:50:54 GMT

He said it was happening in Full Auto mode too. FEC can't be used in Full Auto and the speedlite is locked. So all settings return to default and E-TTL can ONLY be used. Try your camera and speedlite out in Full Auto mode. You can't change speedlite settings it will report "Locked".

Re: Speed light underexposed.

Anonymous — Fri, 02 Jun 2023 23:00:22 GMT

How about we let the OP decide if my advice is good or not. There is no need for you to criticize someone else's advice. My advice is free and worth every penny!

Re: Speed light underexposed.

deebatman316 — Fri, 02 Jun 2023 23:19:34 GMT

The OP is describing different problems. So we need to let them describe the problems separately for both cameras. There are different variables too. They could be using off camera flash. Off camera flash FEC works differently. Then one on camera speedlite does. FEC can be dialed in on the speedlite or in camera. Optical wireless must be done on the speedlite itself. Radio wireless is done in the camera or on the sender speedlite.
No I was not criticizing you. I was only pointing out what the speedlite manual says. I also tried setting FEC on the speedlite and the camera at the same time. The speedlite's FEC took effect and the camera's was ignored. Unless the speedlite's FEC was set to "0". Then the camera's would be applied.

Re: Speed light underexposed.

Anonymous — Fri, 02 Jun 2023 23:34:03 GMT

From what the OP states, it seems it is either a setting on the 70D or a bad hot shoe connection on the 70D, since both flashes seem to work on the T6i (give good exposure).

Re: Speed light underexposed.

deebatman316 — Fri, 02 Jun 2023 23:59:20 GMT

I was thinking the same thing too. Some 430EX II (& 580EX II) speedlites had to have the hot shoe foot redesigned to have "pointy" contacts instead of "round". This didn't affect the 600EX series of speedlites. Usually but not always when those speedlites aren't communicating properly with the camera. The speedlite reverts to Off The Film TTL and will always fire at full output. Since Off The Film TTL is Incompatible with digital cameras. Also the in camera flash menu won't work either. The camera will report "Speedlite's power is turned off, Incompatible Speedlite attached". This is true for some of Canon's speedlites because NOT all of them support the in camera flash menu. Only speedlites released from 2007- present support it. Or it could be a setting problem too. But CF are disable in Full Automatic an other Basic Zone modes.

Re: Speed light underexposed.

rrnkp — Sat, 03 Jun 2023 02:08:00 GMT

Thanks for all the responses.

The 600 ex rt is the correct model, sorry for the confusion.

When photographing I am standing in the same spot, shooting the same scene.

fec is set to zero on both cameras. I even tried changing the lettering on 70d no help.

both flashes fire on the 70d but very low power.

I am using the t6i with the 430 ex ii alone no other flash. The 600 ex rt is not powered on. I power off the 430 remove it and put the 600 on the t6i works as it should. Turn thr flash and t6i off.

Grap the 70d put the 430 on, the 600 is off. Under exposed pic. Remove the 430, it’s off. Put the 600 on same thing. I either have to go manual or +3 on flash.

Re: Speed light underexposed.

rrnkp — Sat, 03 Jun 2023 02:11:00 GMT

Further. I am using the hit shoe on both cameras.

Re: Speed light underexposed.

deebatman316 — Sat, 03 Jun 2023 02:13:00 GMT

Are you using off camera flash. Or just 1 speedlite in the hot shoe. What happens when the 70D is used in Full Auto. Is the picture still underexposed. Please post pictures in the forum.

Re: Speed light underexposed.

Anonymous — Sat, 03 Jun 2023 02:24:33 GMT

The only thing else that comes to mind, is to reset the camera to factory defaults.

Re: Speed light underexposed.

deebatman316 — Sat, 03 Jun 2023 02:27:54 GMT

Or they could try live view. Live view uses a completely different metering system then live view. It sounds like the "weak" flash is possibly the E-TTL pre-flash. Which is 1/32nd power level I believe.

Re: Speed light underexposed.

rrnkp — Sat, 03 Jun 2023 02:30:25 GMT

I have rest the 70d twice. I have not tried live view. Thanks for the tip.

Re: Speed light underexposed.

deebatman316 — Sat, 03 Jun 2023 02:40:51 GMT

It sounds like your only seeing the E-TTL pre-flash. Your camera is NOT firing the main flash. E-TTL consists of 2 flashes but it looks like 1. You have the pre-flash then the main flash. The pre-flash is fired before the shutter is open. The camera uses the pre-flash to calculate the correct flash power.