Flash Exposure Lock (FEL) for repeatable TTL exposures

I'm sure many of you know this but it was an Ah Ha moment for me this morning when I was doing some ETTL testing with my Nissin Air system.

HERE is a post I made explaining the setup and how it can be used.

dmward wrote in post #17948301
I'm sure many of you know this but it was an Ah Ha moment for me this morning when I was doing some ETTL testing with my Nissin Air system.

HERE is a post I made explaining the setup and how it can be used.

Good post; yeah, in the instances that I do use the flash, I always use FEL as I've found it gives me the most consistent results. If I leave E-TTL alone to determine things right at the exposure it tends to overexpose/hit/underex​pose from shot to shot; but nails it for me if I hit the FEL before snapping the shot.

Eric,
Can the Canon cameras be set so that pressing the FEL button sets the exposure and keeps it until you decide to change it.

As I mentioned, I never tried this while using Canon equipment.

nice to know ,,I am starting to try flash a little more ,so I need all the help that I can find

dmward wrote in post #17948346
Eric,
Can the Canon cameras be set so that pressing the FEL button sets the exposure and keeps it until you decide to change it.

As I mentioned, I never tried this while using Canon equipment.

I don't think so; but I'm far from 'experienced' with the flashes. I think it's just like AEL in that it just holds that setting for 30s or so after the button is pressed each time.

That's my recollection.
I just downloaded and scanned the manual and couldn't find anything that suggests the button capability can be changed.

With the A7RII it appears, although I haven't tested it, that the FEL setting says as long as the camera is on and the button hasn't been pressed to toggle it off.

Bit more testing is in order.

dmward wrote in post #17948346
Eric,
Can the Canon cameras be set so that pressing the FEL button sets the exposure and keeps it until you decide to change it.

As I mentioned, I never tried this while using Canon equipment.

You have to continue to hold the button assigned to FEL, to maintain that flash exposure, once you have locked in a flash exposure or if you have released the FEL button the camera will retain that flash exposure for a few seconds after you have taken the shot. Other than that the FEL cancels itself out, a few seconds after the shot is taken. This can be kind of a pain if you use back button focus and you also have FEL assigned to a back button.

On my 5DmII my FEL button is a back button, next to my " AF-ON". So as long as I have my focus set to "AI Servo" I can press and hold my focus button, then aim at the spot I want to obtain a flash exposure for and press the FEL button with the middle part of my thumb while still continuing to hold the "AF-ON" button. Then I aim the focus point at the point I want to focus, let my camera focus and take the picture. Of course this requires planning of the focus point for your framing the image and if that changes then you have to reselct a focus point and start the process over but it is doable. The draw back to this method is that when you have "AI Focus" selected you have no focus assist. I suppose you could release enough pressure on the tip of your thumb to recompose focus in "Single Shot" but my thumb is too fat and not flexible enough for that. I am sure someone though could pull that off.

With my 5DmIII it is a bit easier because I have a Grip which gives me two shutter buttons. Also my FEL is assigned to the "M-fn" button, a small button next to the camera's shutter button. I can lock in a flash exposure with my pointer finger of my right hand and still focus with my thumb on the back "AF-ON" button. When I am ready to take the picture I reach across with the ring finger of my left hand and press the Grip shutter button.

Rand,
Based on that explanation I think I like the way my Sony does it a lot better.

dmward wrote in post #17948421
Rand,
Based on that explanation I think I like the way my Sony does it a lot better.

It is what it is! To be honest as well as the Canon ETTL II system works and with the ability to now choose between "Evaluative" and "Average" metering you really do not need to use FEL. Usually your using ETTL in situations where your distance to subject is changing so locking in a flash exposure is not going to be of any help and may be more of a hassle than it's worth. There is enough focus and recomposing going on without adding FEL and recompose to the mix. It's nice that Sony added that feature but I would have to find a lot more reasons than that to switch to Sony or away from Canon for that matter.

agv8or wrote in post #17948458
It is what it is! To be honest as well as the Canon ETTL II system works and with the ability to now choose between "Evaluative" and "Average" metering you really do not need to use FEL. Usually your using ETTL in situations where your distance to subject is changing so locking in a flash exposure is not going to be of any help and may be more of a hassle than it's worth. There is enough focus and recomposing going on without adding FEL and recompose to the mix. It's nice that Sony added that feature but I would have to find a lot more reasons than that to switch to Sony or away from Canon for that matter.

I agree with your observations. A) ETTL is more intended for dynamic situations, B) ETTL has gotten to the point where minor exposure variations are acceptable, C) Sony's implementation is worth making an equipment change.

I started this test for other reasons and came upon this capability kind of by accident. The one place I do see using it, especially with Godox TTL once its available for Sony, is to get an exposure for a portrait, headshot or group, then activate FEL so that all the images from that portion of the shoot are the same. Just a way to minimize getting proofs ready in Lightroom.

Sony has spot, center and full frame metering area options. I did some experimenting and it appears they work with flash exposure as well as ambient. (More testing to do there as well.)

I'm also going to experiment a bit with using FEC to fine tune the lighting scheme, especially getting a white background for a headshot just right. Then use FEL to "lock" the exposure for the shots that follow.

End of the day, this was primarily a way to demonstrate to the "ETTL is crap crowd" that it works, even if your goal in life is to have absolutely consistent exposures frame to frame.

FEL has been available in various forms across camera brands. The original implementation arrived with the Contax RTS III around 1990, and was patented by Kyocera. I believe Canon avoided infringement by making the flash measurement transitory (RTS III kept the setting across power cycles). You can make Canon FEL effectively permanent by going into the Custom Settings, and changing the appropriate timer that applies to FEL. This customization has been around for a long time, even back to the 1Ds classic.

Any particular reason not to use Manual Flash? No extra buttons to push.

Bassat wrote in post #17948487
Any particular reason not to use Manual Flash? No extra buttons to push.

Not using the flash often enough to spend the time digging into everything necessary to know what settings to use for manual flash.

Bassat wrote in post #17948487
Any particular reason not to use Manual Flash? No extra buttons to push.

Its just another option. Quick and easy.

Snydremark wrote in post #17948549
Not using the flash often enough to spend the time digging into everything necessary to know what settings to use for manual flash.

There is no big trick to doing manual flash calculations. If you can multiply, you're good. The hard part with Canon flash units is remembering the Guide Number at various flash-head positions. Once you wrap you're head around it, the calculations are easy. Then you shoot a chimp shot, or two, anyway. The big benefit is that manual is not fooled by bright or dark backgrounds, shiny or reflective surfaces, or even mirrors. I rely on ETTL in fluid environments.

I've gotten a lot of practice with manual flash calculations since buying a 70D. It totally sucks at bounced ETTL with any aperture slower than f/4.