12-28-2013 10:57 AM
12-28-2013 11:54 AM
I think a trip into the menu settings would be appropriate.
Set everything back to factory defaults. Now try the flash in the P mode.
12-28-2013 12:08 PM
12-28-2013 12:54 PM
The control dial, located on the left side of the camera's top plate, is divided into a Basic Zone and more advanced manual and semi-manual control. The Basic Zone lets you choose from: A+, which is fully automatic, the simplest, point-and-shoot mode and the go-to setting for first-timers.
And not the one I want you to select! Try "P" instead. This is after you are certain the camera and the flash are set to factory defaults.
It is mongo important to get this right before you go to custom changing or accidental changing of things. We must establish that the equipment is all working properly first off.
12-28-2013 01:33 PM - edited 12-28-2013 01:36 PM
Did you test the other cameras and flashes under exactly the same conditions?.
Any time you bounce a flash, you're the mercy of whatever you are bouncing off of.... If a ceiling or wall is too far away, or it absorbs too much light, or is any color other than neutral white, it's going to effect your images.
It could simply be that too much light is being lost in the bounce.... It not only at least doubles the distance light has to travel, many surfaces also absorb a lot of light. Beyond a certain point, a flash simpy won't have enough output to handle it.
Also try using M setting on your camera, with ISO set to something like 400, shutter speed 1/250 or lower and around f2.8 to f5.6 aperture.
All Canon cameras treat the flash as "fill" when used in any of the auto exposure modes.... That's a reduction from full output by -1.5 or -1.7 stops, if memory serves. The camera makes exposure according to ambient light, and only fires the flash partially to open up the shadows.
If you use M or Manual mode instead, the camera treats the flash as the primary or only source of light and will fire "full" flash, ignoring ambient light.
Most of the time when bouncing a flash, you would want to use M I would think. When using direct flash, then it makes more sense to use it as a fill, and switch to Av, Tv or P.
All that aside, one would expect all Canon cameras to give roughly the same results with a flash, everytihng else being equal. I have heard other reports that the 70D tends to underexpose bounced flash. So it might be something we see addressed in a future firmware update. But in the meantime, try M and see if it works better... it makes more sense to use full flash for bounce, anyway.
12-28-2013 02:53 PM
It's possible that you have flash exposure compensation (sometimes called just "flash compensation") either turned up on your old camera or turned down on your new camera.
Your manual will explain how to adjust this either using the on-camera menu -or- refer to the manual that came with your flash to do it using the menu on the back of the flash. Note that if you change it using the menu on the flash itself, it often locks the camera out of being able to change it using the on-camera menu (until you return the flash to the "0" position on flash compensation.)
12-28-2013 06:40 PM
Thank you all for your reply.
Although I did not shoot the different cameras in a studio setting, the conditions were equal. I also swopt the flashes as I thought the 580EX was more powerfull. At the end it made no difference. BTW flash compensation where all set to 0 and with [A+] you cannot set it anyway. And yes, I also expected the cameras would should about the same quality from the same brand, especially in [A+]. Quite a bummer for a more expensive camera.
I noticed that the pictures did had the same ISO setting of 1600 and shutter of 1/60. The pictures where not just a bit darker but a lot with the 70D. You could only see the shapes of the people (70D) and with the 700D you could clearly see the faces. Even in P mode setting the flash compensation to +3 this was not enough. The ceiling was white and about 4 meters. With a lower ceiling it was a bit better, but noticebly darker (about 2 stops).
Does Canon have a known bug list?
12-28-2013 07:09 PM
What the OP is seeing is a fairly well documented problem at this point. I believe the problem is a bug/defect with most (if not all) 70D's. I'm hoping Canon will be able to address this problem via a firmware update.
The problem has been documented in several threads:
In two of those threads I've posted some results of testing I did measuring the flash output with a light sensor and oscilloscope. I believe those results are fairly conclusive that there is a defect/bug with the 70D.
I'll repost my results from that testing here for anyone interested...
Attached image explanation:
Conclusions so far:
Images are fairly large to show all columns/rows/data. I've included links in the summary below so you can download the original size pictures. You probably want to view original size to see all details accurately.
Please let me know if anyone can think of additional testing I can do with a scope to further define the parameters of this defect/bug...
Attached file summary (also links to full resolution pics):
03-19-2014 05:16 PM
05-20-2014 11:03 AM
Thanks bobnburton for all your diligence on this. Has there been any resolution on this issue? I am experiencing similar symptoms on my 70D with 580exii. The underexposure happens with any type of flash modifier (bounce, softbox, etc). I'll get a good exposure if I use FEL, but then focusing exactly on the same subject without FEL the exposure is quite dark. This happens primarily with the 18-135 lens, and most noticeable if zoomed. At wide angle I don't notice the problem. On my 17-55 f/2.8 I don't notice it at all until I zoom all the way out to 55mm (not that much of a zoom) and then I see about 1 stop difference between FEL and non-FEL.
I've tried ISO 400 to 1600, with and without safety shift, all exposure metering modes, and see the exact problem throughout.
The one thing that seems to improve the issue is if I use Average flash metering mode rather than Evaluative. I still see a difference between FEL and non-FEL shots, but much less so (even on the 18-135 zoomed). I guess that's a reasonable workaround, but not sure what else I give up by making that switch. It may be a problem if doing focus lock and re-compose shots. At any rate, there shouldn't be such a huge underexposure issue in Evaluative flash mode.
I'd be very appreciative if anyone can give an update as to what has been found or what actions are being taken on this. I've got an evening event to shoot in a couple of months, and really want a reliable way to produce "soft" light for candid shots with my 70D.
Thanks for any info you have....