Canon EOS 7D introduced

koffiejunkie said:
Speaking of flash and pre-flash, for those who know: If I understand the flash system correctly, it fires a pre-flash to meter, and then again at the correct power along with the shutter. So, if I use a diffuser, which loses some light, it shouldn't matter, because based on the pre-flash, the camera should adjust flash power appropriately.

But this is not what I experience. I got myself a diffuser for my Sigma EF-530 DG Super a while back because I was asked to do a group picture in our company's lobby, which is littered with reflective surfaces, so I thought softening and spreading the light somewhat would help, which it did. But I had to push the exposure compensation on the flash by about 2-2.5 stops before I got a correct exposure that looked right on the screen/histogram, and even then I ended up pushing it even further in post to get it to look right.

Is this normal?
Click to expand...

From what I've noticed with my 530DG Super is that it doesn't give off a pre-flash. I've gotten a diffuser for it and quite a bit of the time my photos come out under exposed. For me to get a properly exposed photo I have to press the FEL button, then the flash will give off a pre-flash and calculate the flash output.
 
koffiejunkie said:
Is this normal?
Click to expand...
It depends - what mode are you shooting in?
chau said:
From what I've noticed with my 530DG Super is that it doesn't give off a pre-flash. I've gotten a diffuser for it and quite a bit of the time my photos come out under exposed. For me to get a properly exposed photo I have to press the FEL button, then the flash will give off a pre-flash and calculate the flash output.
Click to expand...
It does (or at least should if everything is operating normally) fire a pre flash but so rapidly in most cases you wont even notice. You can test it by enabling second curtain sync on the flash and giving yourself a long exposure. Then there will be two distinct pops of the flash.
 
bwana said:
It depends - what mode are you shooting in?
Click to expand...

M if it's dark enough that Av will yield too slow a shutter speed. If I shoot during the day and just use flash to fill out dark shadows on people's faces, I'll use Av

bwana said:
It does (or at least should if everything is operating normally) fire a pre flash but so rapidly in most cases you wont even notice. You can test it by enabling second curtain sync on the flash and giving yourself a long exposure. Then there will be two distinct pops of the flash.
Click to expand...

Good idea. Seems it does with both the Sigma and the pop-up flash.

I guess the meter might have gotten thrown off by the reflective surfaces or just the ambient light. I haven't used the diffuser in any other circumstances yet, and around the house it seems to work fairly well consistently.
 
bwana said:
It depends - what mode are you shooting in?It does (or at least should if everything is operating normally) fire a pre flash but so rapidly in most cases you wont even notice. You can test it by enabling second curtain sync on the flash and giving yourself a long exposure. Then there will be two distinct pops of the flash.
Click to expand...

Oh my bad! I was actually expecting to see a seperate flash before the flash fires like you would see in most point and shoots when you have red eye reduction on
 
chau said:
Oh my bad! I was actually expecting to see a seperate flash before the flash fires like you would see in most point and shoots when you have red eye reduction on
Click to expand...

No, not quite like that. The pre-flash you see in point&shoots, the one that's clearly visible, is to dilate the pupils to avoid red-eye. The pre-flash we talk about with the DSLRs are too close to the main flash to distinguish. That's why bwana suggested I enable second-curtain sync and use a slow shutter time. Second curtain puts the flash at the end of the exposure, instead of the beginning.

EDIT: Interestingly, my lowly CyberShot seems to do a metering pre-flash too. With red-eye reduction disabled, the clearly early pre-flash is gone, but I'm sure I see a really fast double flash when the shutter sounds. I imagine it's just barely describable because, well, it's not exactly a fast camera :)
 
Did you manage to activate second curtain on the camera (via the CF alone) or did you have to set it on the flash?
 
bwana said:
Did you manage to activate second curtain on the camera (via the CF alone) or did you have to set it on the flash?
Click to expand...

I did - thought I replied about that :) I can only set the pop-up flash in the camera - the 50D doesn't seem to speak Sigma... Had to set second curtain on the flash itself (SEL button). In both cases I could see the fre-flash distinctly.
 
koffiejunkie said:
I did - thought I replied about that :) I can only set the pop-up flash in the camera - the 50D doesn't seem to speak Sigma... Had to set second curtain on the flash itself (SEL button). In both cases I could see the fre-flash distinctly.
Click to expand...
On the 400D changing the CF only affects the popup not my speedlite or my sigma.

On my 1D the CF doesnt seem to have any effect whatsoever which makes me wonder what the point of it is because of course there is no popup? :confused:

The 1D does give me the option of controlling the speedlite, incl 2nd curtain, from its own dedicated speedlite menu but that's a whole other thing.
 
Last edited:
Hang on, what are you referring to with "CF"?

The 50D has a menu item internal ad external flash, and as far as I understand the latter should be able to set some things on an attached Canon Speedlight. I'll verify that if I ever get one :) I guess the 7D will probably show you something closer to what I should see if I attach a Canon Speedlight.
 
Aah, I'm with you. On the 50D it's not in the custom functions at all - there's a dedicated menu item for flash control, but yeah, it doesn't recognise the Sigma.
 
koffiejunkie said:
Aah, I'm with you. On the 50D it's not in the custom functions at all - there's a dedicated menu item for flash control, but yeah, it doesn't recognise the Sigma.
Click to expand...

The menu option on the 1D allows me to adjust FEC, ETTL Mode, and enable/disable the flash for the sigma which isnt nearly the same level of control I get with the speedlite attached.

Not much chance of me getting a second speedlite any time soon though.
 
Anyone know if it is possible to set a minimum shutter speed?
 
What I really need is the hard copy of the manual instead of the pdf on my iphone. That will have to wait till tomorrow though. Nice enough little camera though.
 
Yeah but only the body, 16gb cf and two charged batteries were waiting for me at the hotel. Everything else is at the house.
 
Aah. I checked the manual quickly (benefit of a 19" screen at work...). It doesn't mention being able to set either the minimum shutter speed or the maximum ISO. I guess the 550D was the first to introduce this.

What it does do that I like is have Auto-ISO be, well, Auto-ISO in M, instead of being just 400.
 
You must log in or register to reply here.
Back
Top
Sign up to the MyBroadband newsletter
X