dragging the shutter and ETTL

[Seveneer]

Hi,

I've been wondering about the "Dragging the shutter" technique and have been doing a few test shots (which I can't upload right now).

When I had a fully manual SLR (years ago when I was a teenager) I had to set the aperture, when using a flash, to reflect the distance between the flash and the subject. I do the same with my 10D and studio flashes, albeit with the help of a meter.

The theory should be the same for an on-camera flash too, I guess, but when I change the aperture on my 10D the subject brightness does not change. Is this due to ETTL doing its stuff?

If so, does that mean that I should set the shutter and aperture for the background and let ETTL sort out the flash exposure?

Thanks,
/Phil.

[DaveG]

Hi,

I've been wondering about the "Dragging the shutter" technique and have been doing a few test shots (which I can't upload right now).

When I had a fully manual SLR (years ago when I was a teenager) I had to set the aperture, when using a flash, to reflect the distance between the flash and the subject. I do the same with my 10D and studio flashes, albeit with the help of a meter.

The theory should be the same for an on-camera flash too, I guess, but when I change the aperture on my 10D the subject brightness does not change. Is this due to ETTL doing its stuff?

If so, does that mean that I should set the shutter and aperture for the background and let ETTL sort out the flash exposure?

Thanks,
/Phil.

That's the place to start. You have a custom feature in the 10D (#14: auto reduction of fill flash) that will keep the flash from overpowering the ambient light and in theory this is a good safety device. It can also mean that the fill flash is far too weak to show any fill effect on the image so you might want to disable 14.

The bigger problem is with E-TTL. It is always going to make up it's own mind on a shot-to-shot basis as to what the correct output should be. And it does a terrible job of it. E-TTL 2 is Canon's way of saying "We screwed up, but this should fix it.", and E-TTL 2 does seem to work better. The 20D doesn't even offer Custom function 14 (at least for auto flash reduction), so Canon seems to be convinced that it'll work OK.

In any case, with your 10D: turn the Custom Feature 14 off, keep a close eye on your histogram, and use the +/- control on a 550EX flash to fine tune your exposures.

[Seveneer]

Thanks Dave.

So if I'm taking shots in a fairly dark room and I want to drag the shutter to get some of the background detail but use the flash to expose the foregroud subject, I'll need to do a bit of trial and error to get the shot I want. Is that about right?

Sounds like another cracking reason to get the 1D MkII. I shall put the requirement of ETTL II on my list along with the buffer size and spot metering.

Cheers,
/Phil.

[DaveG]

Thanks Dave.

So if I'm taking shots in a fairly dark room and I want to drag the shutter to get some of the background detail but use the flash to expose the foregroud subject, I'll need to do a bit of trial and error to get the shot I want. Is that about right?

Sounds like another cracking reason to get the 1D MkII. I shall put the requirement of ETTL II on my list along with the buffer size and spot metering.

Cheers,
/Phil.

You get the ambient light exposure first - say 1/30 @ f5.6 - and then pop in the flash. Then, if your not happy with the flash output, you can adjust it by using the +/-, at least on the 550EX.

Be careful that your subject's are still or you'll get ghosting, and if your shutterspeeds drop below 1/30 you should be thinking about using a tripod. You can do funky things hand held by dragging the shutter at slow shutterspeeds and the ghosting can be cool. But only in the right place, at the right time and in limited quantities.

E-TTL 2 is also available with the 20D and was at least 50% of the reason that I got one.

[OviV]

Do I get any benefits off ETTL 2 on my 20D with a normal ETTL flash such as the 550 EX or do I need a ETTL 2 flash to reap any of the benefits?

Ovi

[DaveG]

Do I get any benefits off ETTL 2 on my 20D with a normal ETTL flash such as the 550 EX or do I need a ETTL 2 flash to reap any of the benefits?

Ovi

The flashes have not been changed, although the 580EX has been added. If the flash works with E-TTL, it'll work with E-TTL-2.

E-TTL 2 is a function of the CAMERA not the flash and you are getting this function - whether you were aware of it or not - with your 20D if you were using an EX flash.

The E-TTL 2 system requires some focus distance information to be sent from the lens to the camera and not all Canon EF lenses are capable of this. Most notably are the 50mm f1.4 & the 1.8. Canon provides a chart of the non E-TTL 2 lenses http://consumer.usa.canon.com/app/pdf/lens/EFLensChart.pdf so you can check to see if your lens complies. If it doesn't, then the camera will revert to E-TTL.

[edsarkiss]

for something like this, the only way i'd do it is to put everything in manual mode, including the flash.

auto exposure (including flash exposure) is going to be inconsistent as the color of the subject changes. this unpredictability would drive me nuts if i was trying to capture something like balanced foreground (flash-illuminated) and background (ambient-illuminated) shot with a long exposure.

reach back to those simple days of your manual SLR where you were in complete control of the exposure. what you learned then is invaluable.

[Seveneer]

Thanks, but unfortunately I don't have the 550EX just the 380EX so I can't go completely manual.

I shall have to just give it a go and see what happens. :D

/Phil.

[edsarkiss]

doh! sorry to hear that.

nice seven ;-)

[KennyG]

The E-TTL 2 system requires some focus distance information to be sent from the lens to the camera and not all Canon EF lenses are capable of this.

Not strictly true. It is only an additional feature of the new system and ETTL-2 is effective without it. ETTL-2's major improvement is that it uses a pre-flash to take its readings from. The distance readings are additional fine tuning. You will notice a huge improvement over the original ETTL even with a non-distance reporting lens and a 550EX.

[DaveG]

The E-TTL 2 system requires some focus distance information to be sent from the lens to the camera and not all Canon EF lenses are capable of this.

Not strictly true. It is only an additional feature of the new system and ETTL-2 is effective without it. ETTL-2's major improvement is that it uses a pre-flash to take its readings from. The distance readings are additional fine tuning. You will notice a huge improvement over the original ETTL even with a non-distance reporting lens and a 550EX.

As far as I know E-TTL ALWAYS used a preflash to determine the flash output requirements. The problem was that it would change depending on which little tiny area the sensor saw, and was incredibly inaccurate because of that variation.

On that Canon chart that I mentioned above, there's a footnote that explains a double asterisk found by a bunch of Canon lenses as: ** Indicates Distance Information with E-TTL 2.

If E-TTL-2 is fully functional without this information why do they need it at all? I would suggest that E-TTL 2 is just E-TTL, if you don't have the distance information, and would be as good (or bad ) as E-TTL ever was.