4 FLASH UNITS
4.1 What does a flash _do_?
A flash provides light to illuminate a subject. Without becoming a FAQ on general photography, there are two basic uses for a flash. One is to be the primary light source for a scene, the second is to be a fill light to fill in the shadows that occur when the primary light is not coming from same side of the subject that the camera is facing. Most flash units incorporate a set of batteries that charge a capacitor to build up a large electric charge. This charge is then drained quickly through the flash element, resulting in a big flash of light.
4.2 What is a guide number (GN)?
Guide number is a measurement of how powerful a flash is. Here's the scoop. A GN is usually measured in feet at ISO 100. It is computed by taking the best exposure from a series of test exposures and multiplying the distance to the subject by the aperture used. Since this is mostly subjective and done in a lab (and since GN is used by some people as the basis for flash purchases) most GNs are on the high side. You need to find your personal GN for the flash(es) you own.
4.2.1 How do I determine my personal GN?
Do the same thing the flash manufacturer did. Take your flash and your camera somewhere where the flash provides all of the light on a subject. Since this is typically indoors at night, you'll also be measuring the effect of reflections off the ceiling and walls, but that's what the manufacturer did too. Anyway. Set the subject (something with lots of contrasting lines and edges and colors, like a person) some distance away from the camera (which is on a tripod or other non-moving surface). 10 feet is what the manufacturer most likely used but I prefer 5 meters (about 16 feet).
Disable TTL flash metering, stick the flash on full power, make sure the camera shutter speed is constant (manual mode with shutter at 1/100 is the easiest way to do this), take a series of exposures with whatever film you use most often. Remember, this personal GN is indicative of the type of use you put your flash through, not what the lab did) with different apertures. You should use 100 speed film just to come up with an industry standard GN, but you can convert if you use slower or faster film. Each exposure should be a different aperture, starting with the largest and going to the smallest in whatever increments you feel like blowing the film on. In my case, I use a 50mm/f1.7 lens and do 1.7, 2, 2.8, 3.5, 4, 4.5, 5.6, 6.7, 8, 11, 13, 16, and 22.
Develop this film. It's easier to do this next step with prints than slides, but you're supposed to be using your favorite film so you might be using slides. Now, lay all of your images out and pick the one that looks the best. Figure out which image that was and which aperture you used. Multiply your best exposure's aperture by the distance you used and that's your personal GN. In my case, let's pretend that at 15 meters, the best exposure was at f/2.8. That would give my flash/film a personal GN of 42 meters. You can always go closer and try again if you don't have a powerful flash (like 3 meters instead of 5).
4.2.2 How does aperture affect my flash distance?
Assuming that you use 100 speed film, a GN of 30 meters (for the sake of an example) means that at f/1 your flash will illuminate 30 meters, at f/2, 15m, at f/4, 7.5m, etc. Therefore, to figure out how far your flash will illuminate, divide your GN by your aperture. This will be the maximum distance that your flash can cover at that aperture (assuming also that you don't use flash compensation or only partially charge the flash).
4.2.3 How does film speed affect my flash distance?
Since shutter speed does not determine the flash exposure, only the aperture does (except in the case of ambient light flash photography, which this won't begin to cover), changing the film speed changes the amount of light that reaches the film by a certain number of stops. Going from 100 to 200 speed film doubles the light, allowing a one stop reduction in aperture. Going from 100 to 64 is about a 2/3 stop increase due to light loss. Using 400 speed film would be a two stop difference from the 100 speed, and so forth.
Assuming that you have a GN 30m (at ISO 100) flash, that means that at f/1, your flash will cover 30 meters. If you use 200 speed film, you can stop down by a full stop (f/1.4) and still get the same exposure. Therefore, a GN 30m flash with 200 speed film is (30mm x f/1.4) the same as a GN 42m (at ISO 100) flash. The same is true in reverse. If you use 50 speed slide film, and have a GN 30m (at ISO 100) flash, then you have a flash that covers 15m at f/2. Since you have to open up by a stop to shoot the same exposure with ISO 50 speed film, you have to open up to f/1.4 to still get the 15m of flash to subject distance. This changes your GN to 21m (at ISO 100).
There is nothing special about the numbers chosen above to illustrate the GN conversion. It's easier for me to think simply of f/1, f/1.4 and f/2 for the sake of converting GNs.
4.2.4 How does shutter speed affect my flash distance?
It doesn't. The flash lasts for about 1/25,000 of a second. A lot shorter than even the fastest Maxxum shutter speed (1/12,000 of a second on the 9xi and 9). The only exception to this is the 5400HS flash, which is covered separately. Bottom line: flash exposure is determined by the aperture, background exposure by the shutter.
4.3 What is a hot shoe and when did Minolta change the design of it?
The mounting bracket on top of most cameras is called a hot shoe. It typically looks like a narrow C on it's side with electrical contact points in it. All Minolta cameras up through the x000 series (including non-Maxxum cameras that have hot shoes) use an ISO hot shoe. Starting with the i-series, Minolta flipped the C around a little bit to create what is called the iISO hot shoe. This, they claim, helps line the flash up with the lens axis better for AF assist and proper frame coverage. It's mostly a marketing ploy to get people to buy Minolta flash units, but it does provide for a better support for the flash unit on the mount.
4.4 What is a dedicated flash?
A dedicated flash is a flash unit that is electrically connected (though not neccessarily mounted in) the camera's hot shoe. It is programmed to respond to the signals sent by the camera to provide information such as focal length, aperture, and TTL feedback. Compare this to a non-dedicated flash.
4.4.1 What is a non-dedicated (manual) flash?
The basic flash unit is a manual flash. It consists of a light source with no specific interface to the camera other than a trigger signal. The user must set such things as flash output (a percentage of the full output), any zooming to cover the angle of view, and so forth. Typically, manual flash units are much more powerful (ie, have higher GNs) than dedicated flash units, because more space can be devoted to flash electronics instead of camera interface electronics. With a manual flash, the operator must be very aware of the GN, the aperture, and the flash to subject distance to correctly compute the exposure settings.
4.5 What is TTL flash metering?
Through The Lens (TTL) flash metering is a method that the camera uses to detect how long to leave the flash on to achieve proper exposure. In all Maxxum series cameras, TTL is Off The Film (OTF) which means that the light reflected from the film is what is examined.
4.6 So what flash units are there?
There are three basic types of Minolta flashes these days: Non-Maxxum (for pre-Maxxum cameras), original (ISO) Maxxum flashes, and the current i/xi/HS series (iISO).
4.6.1 What about the pre-Maxxum flashes?
I don't know much about them at all. Anyone?
4.6.2 What about the ISO Maxxum flashes?
There are three ISO Maxxum flashes, the 1800, 2800 and the 4000. The first two digits represent the GN is meters at ISO 100. The 2800 is a basic flash offering a high and low setting (low is 1/2 flash output) while the 4000 has a zoom/tilt/swivel head and a much more programmable interface.
4.6.3 What about the iISO Maxxum flashes?
These are the newer Maxxum flashes, and even though most have i or xi in the model number, all will at least perform basic flash functions with any i, xi, or si series camera. They are the 2000i, 3500xi, 5400xi, and the 5400HS (which is a souped-up 5400xi). The 3500xi, 5400xi, and 5400HS are all zoom/tilt flashes (the 5400 series also swivels), while the 2000i is a simple dedicated flash.
There ware two another iISO-shoed flashes for the 3000i, the D-314i and D-316i, which drew their power from the 2CR5 in the camera and could not be used off-camera.
4.7 Summary of Compatibility and Features
|1800 AF||5000, 7000,|
9000 only *
|2000i||i, xi, si|
* - the x000 series flashes can be used with later cameras when mounted using the FS-1100 flash shoe adaptor; however, auto switchover and AF illuminator cannot be used. The 4000 also fits the CG-1000 grip.
Flashes with (D) designation use subject distance information from new (D)-type lenses in conjunction with the Dynax 7 body.
+ - 24-85, also 17mm wide adapter panel is also available; manual still available online konicaminolta.com.hk/ph/eng/pdf/owner/la_3600.pdf
External power pack EP-1 uses 6 'C' sized batteries.
Power Grip CG-1000 uses 6 AA batteries.
4.8 Battery Life with 5x00 Flashes and the EP-1
Date: Mon, 09 Nov 1998 11:13:48 -0500
From: "Noel J. Bergman" (firstname.lastname@example.org)
The question comes up so often about battery times on the 5400HS, with and without a battery pack, I am posting this information to the list so that it will sit in the list archives.
|5400HS||EP-1||Flashes||Recycle Time||Max Recycle Time
|Alkaline||----||100-3500||0.1-11 sec||30 sec
|NiCd||----||40-1200||0.2-6 sec||10 sec
Even when the external power pack is attached, the internal batteries are important. Minolta recommends against putting Alkaline batteries in the EP-1 and NiCd batteries in the flash. Minolta also notes that if you have drained batteries in the flash, performance will be diminished even if you have fresh batteries in the EP-1.
The first set of numbers are reported from the 5400HS manual, and the second set of numbers is reported from the EP-1 manual. The latter set assume a full discharge at 1/1 power setting, whereas the former set cover an unspecified range of performance parameters.
4.9 The DR-1000 Flash Meter Data Receiver
The Flash Meter IV, coupled to the camera via the DR-1000 allows the DR-1000 to receive aperture and shutter settings from the meter, but has no affect on any other settings in the camera. The DR-1000 cannot be used with the 700si.
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