Newbie in bad need of slave flash pointers

Hi,

I have purchased a cheap slave flash to improve upon the very modest capabilities of my Canon PowerShot 570 IS. Since I am on a very tight budget (hence my camera choice to begin with), I ended up buying a Phoenix D92-BZS (though Amazon was selling it under the name Pro Digital 328). At least one other Canon 570 IS user was very happy with it. I figured that for $30 that was a good pick.

The specs on the box of the flash are:

Flash duration 1/1.000 - 1/20.000
Color Temp: 5600K
Guide Number (50mm@ISO 100) 92
Auto ISO 100 f/stop 2.8 in "S" Position
Mode Selector Switch: 3 Positions - N, S1 & S2
Zoom range (4 positions): W1 28mm -W2 35mm -S 50mm - T 85+mm
Angle of coverage Horiz. 60deg, Vert. 45deg.
Slave: yes
Ready light: yes

I am totally confused as to how to use it. The small insert recommends setting the white balance on 'auto', the flash 'on', ISO at 100, aperture at 2.8 and speed at 60 (which I suppose means 1/60th sec). With these settings the photos come out no better than with my built in flash.

When I try bouncing off the flash off my ceilings the results are even worse - photos are dark. I tried all sorts of setting, mainly in the Program mode (choice of ISO, built in flash output, and -2/+2 exposure compensation) and Manual mode (same as program, but with speed and aperture choice and without -2/+2 exposure comp).

In program mode the S2 position (double pulse flash on camera) works, whereas on Manual S1 (single pulse on camera) works (or the other way around, I am not sure now) and sometimes the unit does not fire.

Though I am a real newbie with digital cameras, I use to have a basic Chinon all manual 'reflex' camera with a flash on a hotshoe as a teenager and I never had flash problems, even bouncing light off the ceiling was really easy.

Now I am totally confused as to 1) I got a crappy flash 2) the flash does not work as it should or 3) I am doing everything wrong (the latter seems most likely).

What should I read to try to learn how to use this flash, in particular to make portraits in low light conditions indoors while bouncing the light off the ceiling. Can I learn how to make this flash work, or did I screwup and buy a lousy unit? Should I return it and get another make and model, or are all slave flashes which are triggered by a first flash so lousy?

Guys, please help me out as I am totally confused and frustrated.

Many thanks in advance for any and all pointers!

Mamadu

PS: I should probably mention that my main goal was to learn how to do portraits indoors because the built in flash make all my subjects look very pale, like corpses, using the 4x zoom did not help, and that in larger rooms I had black zones on the sides. I am trying to get an artificial "soft" radiating light for portraits (when sunlight is available the Canon PowerShot A570 IS does a great job, but without using the flash). All I need a flash for, really, is portraits when sunlight is not available and bouncing the flash's light off the ceiling is, I figured, the best way to achieve this.

Does your camera put out a preflash that's causing problems?

Re pale, play with white balance. If you can set it manually use 6500K. If you shoot RAW just adjust it later.

tim wrote in post #5512330
Does your camera put out a preflash that's causing problems?

Not that I can see. What happens is that a red light turns on before the flash fires off, but I only see one flash generated.

tim wrote in post #5512330
Re pale, play with white balance. If you can set it manually use 6500K. If you shoot RAW just adjust it later.

My white balance control has the following settings:
Auto, Day light, Cloudy, Tungsten, Fluorescent, Fluorescent H, Underwater and Custom (which fires off the flash to set the white balance). Temperatures are not provided.

My camera is not RAW capable, but has only JPG. I can use the GIMP to retouch the pictures if needed, though I never tried that with 'corpse looking portraits'

Do the specs of the flash look decent to you or did I buy an underpowered piece of crap?

To use that type of non-dedicated off camera flash, 2 rules usually applies:
1) the camera has to be in manual mode. The camera does not know an external flash is added, you set the camera to a fix exposure, and try to adjust the flash to match that exposure.

2) The built in flash has to be in manal mode or turned down the power output. If both flashes are firing in auto mode, the camera does not know how to set the right exposure for both flashes.

One problem that flash has is that it only give one auto setting @ f2.8, and the 570's lens has a varible apterture of f2.6-5.5. So to get a correct flash exposure, you are limited to wilder zoom end of the lens.

There're very limited choices for "digital" slave flash in that price range, before you decide to return it, give this setting a try: camera to M, iso100, f2.8, 1/60. If the 570 has manual flash output, set it to the lowest, and set the digital slave to N. If the 570 has no manual flash, set FEC to -2, set the digital slave flash to S1.

Good luck.

Lotto wrote in post #5513786
One problem that flash has is that it only give one auto setting @ f2.8, and the 570's lens has a varible apterture of f2.6-5.5. So to get a correct flash exposure, you are limited to wilder zoom end of the lens.

Can I somehow compensate for that? For example, could I either slow down the shutter speed, or set the flash for a different zoom setting (I have the choice of 23 feet, 28 feet, 33 feet and 38 feet) or by increasing the ISO to 200 or even 400?

Are there some tables of equivalence for this kind of stuff, or is trial and error the only way to do that (assuming that is possible, of course).

Also, do these auto settings assume that the flash and the camera are at the same distance? Maybe I could place the flash 10 feet away from the subject I want to take a portrait of while standing about 20 feet away with my camera thus getting a narrower angle better suited for portraits?

The A570 does use a pre-flash to set flash exposure; you need a "digital slave" that will ignore the pre-flash and only fire on the "real" flash to trigger your slave successfully. If I'm reading your original post correctly, that's the "S2" setting.

The "Zoom settings" aren't (directly) for selecting range; what they do is set the angle of coverage of the flash; for a 28, 35, 50, or 85 mm lens. Because the beam is more spread out to cover a 28 mm lens, it only provides adequate light out to 23 ft. at that setting. The narrower, more concentrated beam of the 85 mm setting will provide the same exposure to a subject up to 38 ft. away., but only if you've zoomed your camera's lens to 85 mm (equivalent) or longer. Your A570's shortest zoom length is equivalent to the 35 mm setting; you don't need to set the flash any wider than that unless yo want the flash to be closer to the subject than the camera is.

You can use the "Guide Number" to compute the positioning of the flash for proper exposure in manual mode; to do this, set the camera in aperture priority or manual mode (you want to set the aperture), ISO to 100, the flash head's zoom to 50 mm, and divide 92 by the aperture value you're using. The result is the distance in feet the flash should e from your subject to get a "correct" exposure. If you bounce the light off the ceiling or a wall, use the value for the next smaller f/stop (set camera at f/5.6 but calculate using f/8, for example), and use the distance from flash to reflector and reflector to subject, not just straight flash to subject distance. You'll lose about 1 stop of light by bouncing. If you set the flash head to the 85 mm setting, use a Guide Number of 106; at 35 use 78 and at the 28 mm setting use 64. If you use ISO 200, multiply the GN by 1.4; at ISO 400 multiply by 2.

Jon,

Thank you so much for those most useful and interesting pointers! I really appreciate it. I will try out all your suggestions and let you know what happens. Again, thank you very very much!