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dg
Occasional Contributor
Posts: 5
Registered: ‎06-03-2014

Re: 70D bounce flash

I just purchased a 700D (T5i) and the bounch flash works fine, including with wireless TTL triggering.

It is true that the camera feels a lot cheaper than 70D, but I paid less than half of the price of 70D after all.

 

In all fairness 700D has a bit more noise at high ISO (6400), but I will not need to go there at all - the TTL flash gives me more than enough light at ISO 400. Also 70D AUTO ISO goes to 1600 once you move the flash head from the direct position, while 700D stays at 400 and still has enough light for proper exposure.

 

Until Canon fixes the TTL in 70D I would recommend 700D for anyone who does not need the extra 10 focus points. With the rest of the money you can buy another lens or just go on vacation.

 

New Contributor
Posts: 4
Registered: ‎12-28-2013

Re: 70D bounce flash

Yeah...it's pretty sad when a camera half the price works better than the higher end camera.

 

I don't know why its so freaking hard to release a new firmware update...I mean I fully understand that they need to do a lot of testing on any new firmware updates...but come on.  It'll soon be a year since release of the camera.  Just fix a few of the bugs and push out a firmware already.

one
Occasional Contributor
Posts: 7
Registered: ‎12-28-2013

Re: 70D bounce flash

The 650D/700D is the better buy. Although it has less features then the 70D, it is has them better implemented

 

Some of the features of the 70D are not implemented quite user friendly. Like HDR and multi exposure, why are the not in the Scene [SCN) menu? Easer to access and no need to digging into the menu.

 

There is also another bug I haven't seen anyone mentioned before. With the 18-135 STM, when I zoom to 135 and focus into a object close by, then try to focus something in the distance, it refuses to focus. I have to zoom out first, focus, zoom back to 135 and refocus before it works. I haven't seen this on the 650D. Hope this gets fixed too in a firmware release.

 

one
Occasional Contributor
Posts: 7
Registered: ‎12-28-2013

Re: 70D bounce flash

I would like to add that the focus problem I mentioned does not occur in Live view.

Occasional Contributor
Posts: 5
Registered: ‎08-17-2014

Re: 70D bounce flash

Bobn4burton, I add my kudos for your hard work trying to find a solution to this issue.  I'm new to the discussion, but I agree that this is a 70D problem (an otherwise wonderful camera).  As a new 70D owner having the same problem with underexposure of shots while bouncing the flash, I was stumped about the problem until I read the threads at DPREVIEW.  All the suggestions about operator error and to try this and try that are just noise.  The problem does not exist with the 430EXII with my XSi in the same conditions using the same lens.  The FEL button fixes the problem, but that indicates that something is not right with the normal (non-FEL) flash sequence.  The camera is just not calculating the correct primary flash power required to get a correct exposure.  It’s not even close (several stops underexposed).  I do hope Canon addresses the issue.  

Occasional Contributor
Posts: 5
Registered: ‎08-17-2014

Re: 70D bounce flash

Tim:  Can you confirm whether Canon is currently working on a firmware update to address this problem with the 70D?  Do they need more data from users related to this issue?  The problem is actually pretty easy to document, even without a laboratory.  First you reset the 70D and a Speedlite 430EXII to factory settings.  Then in a uniformly dark room, set the camera to full auto or P and the 430EXII to ETTL and take a picture while bouncing the flash off the ceiling.  The result is a significantly underexposed picture.  Then keep all the settings the same and take another shot after depressing the FEL button.  The result is a correctly exposed picture.  The evidence suggests that if you don't select FEL, the camera does not calculate the correct power level for the primary flash (you can actually tell with your peripheral vision that it's a weak flash--much weaker than the flash after selecting FEL).  I've run the same experiment using my XSi body with the same lens and flash and you don't need to select FEL to get a correct exposure.  I'm new to the process, so I'd appreciate any advice you can give for getting this issue resolved.  Since many other 70D users have reported the same problem, it seems to be a 70D issue rather than a malfunction in any individual camera.  It's fortunate that there's a workaround, but Canon should fix the problem so we don't have to rely on a workaround.  Thanks! 

New Contributor
Posts: 3
Registered: ‎05-20-2014

Re: 70D bounce flash

I've gone round and round with Canon on this problem.  It was escalated to their engineering group.  I sent many examples of the problem with simple instructions on how to duplicate.  They did duplicate it, and responded, basically, that this is the way the camera operates.  They never really addressed the actual issue of underexposure without FEL.

 

Their response: "We were able to reproduce a similar result with a little testing.  The cause of the difference you are seeing is that the metering used with FEL is essentially spot metering.  If you are zoomed into an area with a lot of light colors, the image may be underexposed because the light colors are "tricking" the metering system.  Using FEL essentially allows you to pinpoint where the flash exposure metering will happen, and if you're using FEL over a mid tone region such as a person's face, it will produce a correct result, even if everything around them is bright white.  I would recommend using FEL if at all possible in tricky shooting situations. Please let us know if we can be of any further assistance with your EOS 70D. Thank you for choosing Canon."

 

This response doesn't make any sense to me, in that the samples I sent were of a blank sheet of light brown cardboard.  There were no "light colors" to :"fool" the metering system.  On a uniform piece of cardboard, spot metering should NOT produce a different result than evaluative metering.  They did not answer why the standard Evaluative metering was not being done correctly and was always underexposed.   I, too, believe that the 70D flash system does not expose correctly when using bounce flash or any flash modifier.  My 40D did not have this issue.  They have also suggested that because I wear glasses, light it entering the viewfinder and messing up the exposure.  This is not the problem as I have totally blocked the viewfinder, also testing in LV mode, and the same problem exists.

 

On a brighter side (pun intended), I did find that this problem with the 70D can be mitigated somewhat by using "Average" rather than "Evaluative" for the ETTL flash metering (in Flash control menu, pg 195 of 580exii manual).  I'm pretty much able to use a flash modifier or bounce flash with my 580exii, when using ETTL Average, without having to do an FEL first.  This is only a bandaid, and the downside to this is that if you may occassionally overexpose your subject if the rest of the scene is very dark, as the flash tries to make the total image average out.

I, too, wish that Canon would correct their problem with the 70D grossly underexposing with modified flash.

Occasional Contributor
Posts: 5
Registered: ‎08-17-2014

Re: 70D bounce flash

Thanks for the info--and for trying to fix the problem with Canon.  It's unfortunate that they're not willing to fix the underlying issue.  I agree that they're obfuscating the issue when they say it has something to do with FEL's use of spot metering.  As you point out, you get the same (incorrect) result even in a room of uniform darkness.  So it's not that the meter is being fooled.  Evidently the algorithm the camera uses to calculate the primary flash power in FEL mode is different from what it uses when you're not using FEL. 

 

Thanks for the tip about using Average vs Evaluative mode.  I'll give that a shot.  I'll also chime in with Canon.  If they get enough feedback from unhappy customers, they'll be more inclinded to provide a fix.

 

Other than this issue, the 70D's a wonderful camera! 

Esteemed Contributor
Posts: 4,984
Registered: ‎06-25-2014

Re: 70D bounce flash

[ Edited ]

dg wrote (sometime in June):

I visited 2 real camera stores and asked about the underexposure. In the first store they guy spend the time with me, reproducing the problem with both my flash and the 430 EX II from the store, on a 70D body that they use as a demo. The clean experiment is like this:

1. Put the flash on manual, 1/2 power, pointed up (75 or 90 degree, with or without the bounce card)

2. Set the camera to M, shutter 1/200 and find a combination of ISO and apperture that provides proper exposure on the subject (about 1 m from the camera) - ISO 400, F/5.6 should be OK

3. Now switch the flash to TTL and you get a very underexposed picture


The gentleman told me he has never heard of this issue before, but obviuosly there is something. He suggests compensating for the overexposure, until hopefully Canon releases a firmware update.

 

In the second store I spend some value time with the guy in charge of accepting cameras for repairs to be sent to the manifcaturer. He denied any prior knowledge of the issue too. In his opinion the TTL is supposed to work only with the flash pointing directly at the subject, so the bounce should be expected to fail. He could not explain why this used to work with the old (XSi) body.

 

I tried to get some info from other photographers using the Canon system, but seems like the case of overpowering the existing light with the flash is not that common and when it is done it usually involves manual flash mode and softboxes. The TTL is used predominantly for fill flash.

 

This concludes my investigation - there will be no new Canon equipment in my camera bag. Unless I read somewhere that 80D magically fixed the issue, but I will not be holding my breath.


I have no dog in this hunt and little or nothing to contribute to the technical discussion that has taken place over the past several months. I do, however, have two points to make:

 

1.  The term "TTL" has been bandied about freely in many of the articles posted. Modern Canon cameras use E-TTL (Enhanced TTL), rather than the original TTL. They are not at all the same. If you set a Canon flash to TTL on a camera that expects E-TTL, you will get bizarre results. The flash always fires at full power, and most pictures are dramatically overexposed.

 

2. The guy in the second store is wrong. My experience with several E-TTL cameras (50D, 7D, 5D3) is that E-TTL's fill flash fetish works much better (or does much less harm, depending on your point of view) with bounce flash than with direct flash. Why that is, I'm not really qualified to explain, but it must have something to do with the fact that by the time the highlights are fully exposed, the rest of the scene has been illuminated as well. If this isn't the case on the 70D, I think it does support the contention that there's something wrong with the way the 70D calculates its desired flash power (or possibly in the way it communicates that calculation to the E-TTL flash unit).

Bob
Philadelphia, Pennsylvania USA
New Contributor
Posts: 3
Registered: ‎05-20-2014

Re: 70D bounce flash


 

Thanks for the tip about using Average vs Evaluative mode.  I'll give that a shot.  I'll also chime in with Canon.  If they get enough feedback from unhappy customers, they'll be more inclinded to provide a fix.

 

Other than this issue, the 70D's a wonderful camera! 


I like the 70D as well, but it has two significant drawbacks, and they interfere with each other.  First is this flash underexposure issue when using a modifier/bounce, that can be mitigated somewhat by using FEL.  The second is erratic focus with the viewfinder on 2.8 or faster lenses (many of us have experienced this issue, MANY forum threads about it) that can also be mitigated, by using LiveView.  Unfortunately, you can't use FEL when in LiveView.  So... if you want consisten focus and correct flash exposure, these two workarounds cannot be paired together.  You get one or the other.

 

A fix for this ETTL Evaluative flash issue would make this camera reliable, especially if photographing an evening event.  As is, it is not.  It requires lots of trial and error to get a correct flash exposure, hardly suitable for a fast moving event.

 

DOES ANYONE FROM CANON EVEN READ THEIR OWN FORUMS?  Your engineering group has already recreated the flash problem yet has not provided a viable explanation or a fix.  How about some answers?

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