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Old Feb 17, 2006, 5:51 PM   #1
aoz
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to all,

I just bought a DigiSlave 3000, for use with a CAnon Powershot SD500. I use this camera in Manual mode, but am not an expert at camera settings.

I'm somewhat confused with the Manual/Auto settings, on the flash (similar to other flashes), and the slider for ISO/DIN settings. I mainly want to be able to lower the light (overexposure on test shots currently), and understand how to better control the flash, as a slave unit.

It is a nice unit, but a crash course, in Flash 101, (or links of where to read info) would be appreciated.

I DID read the one link in here, with about 5 pages, on external flashes, and it makes sense,but I need a little better understanding of the actual settings, to better control this unit.

thanks

Nick


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Old Feb 17, 2006, 6:31 PM   #2
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Nick:

You probably won't be able to get it "just right" at all focal lengths (amount of zoom) and desired subject distances without some exposure error or tweaking required.

You don't have a true manual exposure mode on your SD500 (where you can set both the aperture and shutter speed), with the exception of the long exposure mode (where you can set shutter speeds from 1 to 15 seconds), from what I can tell looking at your camera's specs.

Do you have the manual for the flash? From the little bit of info I found on it, it has 2 Auto Aperture Modes (as well as the ability to be used in manual).

You're probably seeing a scale on the back of the flash that shows you an ISO speed scale, with appropriate ranges based on the aperture you're using on your camera.

The idea when using the auto modes is to find a good combination that works with your camera (aperture range on the flash, aperture and ISO speed settings on the camera), and let the flash control it's own output via how much reflected light it sees during the flash exposure. When it sees enough for the selected aperture range, it automatically terminates it's own output.

I can't tell what it has in the way of manual settings from the specs, but if you have finer control that way, you can use the distance scale built in to estimate it (based on what your ISO speed is set to and what aperture your camera is using (it will shoot at wide open apetures in low light, but the aperture will vary based on the amount of zoom you use). So, you'd need to learn it's behavior.

If you're seeing overexposure in both auto modes on the flash, try setting your ISO speed to a lower value on the camera. The Auto ISO is going to increase it in low light.

You don't have direct control of aperture on your camera, and the camera is going to shoot at wide open apertures in low light. That would be f/2.8 at it's wide end, dropping off to around f/4.9 on it's long end as more zoom is used (more than twice as much light reaches the sensor on the wide end).

So, if you get the setting combinations working right (auto aperture range on flash, ISO speed on camera) at one focal length (how much zoom), it could be off at another (correct exposure on the wide end of the lens could mean underexposure on the long end of the lens).

That's because more than twice as much light will reach the sensor through the lens on the wide in with your model, compared to when you're zoomed in all the way. You'll also lose the light provided by the built in flash on the long end (and I don't see an easy way to control it's output based on a quick glance at your camera's review here).

Your best bet is to experiment with it (and ISO speed is about the only thing that you're going to be able to adjust on the camera to influence flash exposure with it unless I'm missing something), using both of it's auto aperture ranges to see what works best at the ranges you shoot at.

You may need to change the ISO speed on the camera to a higher value when zooming in, once you get everything working right at the lens' widest zoom setting.


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Old Feb 17, 2006, 8:00 PM   #3
aoz
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Jim,

thanks for reply. The manual (actually only a couple page pamphlet) just lists what the settings are for red and yellow, but I'm confused with their slide bar, and I emailed the manufactureer with questions on this, as to what button controls what settings.

I know it's going to take some experimenting, and that is what I am currently trying to figure out on the flash; On the camera, I'm comfortable with changing every setting in thte manual mode; the easiest one so far is actualy the exposure; I can go to a (-2) level, and that helps somewhat.

Your response does help clarify some things for this.

An example of the confusion; on the back of hte camera, one line lists
28 mm 1.4 2 2.7 3.9 5.5 7.8 11 meters
35 mm etc etc
50 mm etc etc
I don't know what those numbeers represent, and what they are cross-referenced to. Are they just distances? and if so, distances as related to what?

And I can't tell if that is from a MANUAL setting, or an AUTO setting

again, any further info apreciated,and I also hope the manufacturer can help me.

I am a 20+ year user/builder/teacher/programmer of computers; but as much as I know about computers is how little I know about flashes. I just want the flash for general low-light shots, no super-photo contests, etc. I got this flash as its predecesor was recommended on steve's site, adn it handled pre-flashes.

thanks

Nick


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Old Feb 17, 2006, 8:17 PM   #4
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Experiment with the ranges on the flash. That's probably all the color codes are telling you, and they probably correspond to scales on the flash for distance and aperture depending on your selection, with a sliding scale based on an ISO speed setting on most, too (which usually just changes the readings on the scale, without impacting the flash power/auto range selected).

As for the mm settings you see, it sounds like it's got a zoom head on it (you pull the front of the lens on the flash out out for longer focal lengths, or keep it in for wider flash coverage).

For flash units so equipped, you'll get different distance ranges for the settings, depending on the zoom head position on the flash (which is designed to correspond to your lens focal length in mm, increasing your range when a wider flash is not needed, more narrrowly focusing the flash when a longer focal length is used for more distant subjects by zooming in with your camera).

As for using a -2.0 EV setting on the camera, that could be acting as Flash Exposure Compensation, too (allowing your camera's flash to supply less light). That's probably a good idea (leaving it dialed back some), so that your slave is the primary light source.



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