40D & Canon HF-DC1 - Will it work?

[digitalirony]

I've recently bought a 40D and am now happily trying all of the things that I never

had the patience to try using my film bodies and have hit a small problem.

 

I'm trying to find a relatively cheap way of experimenting with off-camera flash, and

after reading online and even posting a message on the Lighting Equipment and

Techniques forum (http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=00PYV8)

here at photo.net am beginning to understand the cheap may not be possible.

 

The main problem is that the 40D uses preflashes for exposure calculations when

my 420EX is attached which rules out using optical slaves. Why it should try to

use E-TTL exposure calculations when I'm in manual mode is a mystery. I

appreciate that I can be handy when you just want to point and shoot and let the

camera work out the exposure, but, the fact that it can't be switched off when you

want to experiment with other techniques in incredibly annoying.

 

Enough preamble ...

 

Continuing my research today I've come across the Canon HF-DC1 flash unit for

Powershot cameras. I can't find much info on this flash unit even on the Canon

website (http://www.canon.com/camera-museum/tech/report/200707/table2.html),

however, it does have three power settings & it does say that the flash is

compatible with "Cameras with a built-in flash that fires the main flash between 70

and 150ms after a single pre-flash".

 

So the questions are ...

 

Does anyone know how many pre-flashes the 40D uses in manual mode with 1.

the pop up flash and 2. the 420EX Speedlite unit? And if it isn't more than 1, how

long duration between the pre-flash and the main flash is?

 

If I could use the HF-DC1 it would be a cheap and cheerful way of experimenting

with multiple flash units.

[bobatkins]

As far as I know there is a single preflash. I don't know what the timing is.

 

However you mighty be better off with one of the many generic "digital slaves" which are available, since most of them can be switched to deal with various numbers of pre-flashes and flash timings.

[mark u]

You could try measuring the timing of the preflashes if you have a digicam with manual exposure options. In a darkened room set an exposure on the digicam with a slow shutter speed - 2 seconds or more perhaps. Arrange a rotating or falling object whose speed you can calculate, and illuminate it with the flash from you DSLR (preferably from fairly close so the main flash and preflash are more similar in strength). You should be able to pick the preflash and main flash in the digicam image and estimate the delay between them.

[robin_sibson1]

On the assumption that what you want to experiment with is photography not electronics or physics, I would guess the HF-DC1 is likely to be a frustrating and unrewarding road to go down. A good modest-price option would be to look for a s/h 550EX and an Off-Camera Shoe Cord. That will allow the 550EX to be a small way off the camera and the 420EX, as a wireless slave, to be wherever you want.

[chrisjb]

As far as I can see the hf dci is a slave flash, it seems to pre flash with the P&S on board flash to meter, the 420ex has not any manual mode, the 430/550/580 Ex`s have manual mode that does not preflash. Other cheap alternative is a ebay radio trigger and any ol thyrister flash :)

[digitmstr]

The 420EX doest NOT support MANUAL operation therefore, it CANNOT be triggered by an optical slave.

 

IF you are talking about using the 420EX to trigger a separate, manual strobe this could be done with a 'digital-slave' which is essentially an optical slave with a variable delay to compensate for the pre-flashes of dedicated strobes. I have one from WEIN and it works great.

 

Better yet, get an ST-E2 and you are set.

[digitalirony]

Thank you Bob, Mark, Robin, Chris & Giampi for taking the time to respond.

 

After having some time to look into the matter (dismal wet Bank Holiday weekend here in the UK), I've come to the conclusion that I really only have two options.

 

Option 1; would be to pony up about GPB 150.00 for a second hand 550EX as suggested by Robin, plus whatever it costs for an off camera cord. I'd have to learn about flash ratios, so that I have some measure of control of the light output on the 420EX which would be triggered by the 550EX, or,

 

Option 2; I eschew E-TTL altogether and buy a cheap radio trigger and a couple of slaves along with some cheap manual strobes. If I choose this route then the cheapest way to do this seems to be to buy an eBay/cactus V2s trigger and a pair of receivers and a pair of Sunpak 383s for about GBP 230.00.

 

As there isn't much between the two in terms of cost, I'll have to decide which way to go based on reliability, ease of use and level of control.

 

I'm guessing that option 1 would be simpler to use and there will be less equipment to carry around in my bag or to go wrong in use, but as the 420EX doesn't not allow manual control may be harder to set up consistently.

 

As this is just a hobby the convenience of having less to carry around or to have to 'debug' when something goes wrong is quite appealing, also if I get the 550EX then I suppose I could get another EX flash in the future with manual control if I like the mutli strobe stuff.

 

I don't have the money to buy either set up for the next couple of weeks, so I think I'll read more and take my time coming to a decision. If possible I'll see if I can borrow a 550EX or a 580EX to try it out.

 

Once again, thanks for the input.

[chrisjb]

Something to start reading, mainly about candids but may give a few ideas, if you have not seen it. Also plenty in photonet notes.

 

http://super.nova.org/DPR/Canon/MultiCanon/

 

HTH :)

[digitalirony]

Thanks Chris,

 

Good article, explains a lot.