Metz Flash, help!greenspun.com : LUSENET : Large format photography : One Thread
Hi. I got a Metz 45CL-1 because the sun never shines around here, but now it is spring and I probably don't need it. I've never used a flash before. The instructions and the dial on the head have index for range and f-stop, but there is nothing for shutter speed. I'm using this on a 4X5 with lens in shutter that I understand will flash at any speed. But what speed would I sit the shutter for, for a portrait? I'm sure there is something basic about this I just don't know, sorry for asking what must be simple thing.
-- david clark (email@example.com), April 25, 2002
Hi David, it all depends what kind of effect you want to achieve.
IAs you rightly say, you can use any shutter speed, this gives you the freedom to compensate the exposure to include the available light. for instance: if the reading to have a correct exposure in the background is 250 f. 11 and your subject is in the shade then you want to set the shutter speed at 250 and the f stop in the camera at f 11, the dial on top of the flash instead it is prefferable to set it at f 8 . This will give you more realistic skin tones. The skin tone of caucasian people is one stop lighter than the standard light meter calibration, or factor K . For darker skin tones use the nominal reading.
If i were you, in case you havent thought about it, i would bounce the light to achieve a more soft light , more flattering, your flash is powerful enough for that. You need to experiment, and see what is closer to your liking.
-- domenico (firstname.lastname@example.org), April 25, 2002.
if you use a flash, all the light that will exposure your neg will come from the flash except the daylight is very bride or you want to mix daylight and flashlight. So the normal case is flashlight only: choose the f-stop you like or need, set it on the lens and on the flash and the sensor of the flash will do the rest. That means if the time or lightning from the flash should be long enough to get the right exposure the sensor will stop it. This happens within milli- seconds. Therefore you can choose any time on the shutter (because it is a central-leaf-shutter), but the choosen time shouldn't be so long that the daylight could affect the exposure or shouldn't be shorter than the longest flash-period (could be 1/400 sec, so avoid 1/500 sec on the shutter). Because the short time of the flash is practically identical with the exposure-time, a normal speed of 1/60 or 1/125 sec on the shutter should be best. The right f-stop can also be calculated if you set your flash in manual mode. f-stop=guide- number/distance. Yor flash has guide-number 45 for 100 ASA.
-- Thomas Vaehrmann (TVaehrmann@web.de), April 25, 2002.
Both gentlemen that posted before me are correct, but I think that they did not answer your question why there only is a f stop dial on the flash:
Well it's very simple, in normal daylight (or continues light) you control the amount of light that reaches the film by choosing an appropriate shutter speed and F stop (how long you open the door and how wide) given the filmspeed. Light from a flash is not continues light, it is a pulse with a fixed duration (known by the flash). Thus the flash pulse acts like the shutter, the only thing that has to be done is choose a f stop on the lens en set the flash to that same f stop to get a well exposed film (basically, but not always true). Because the pulse is (more or less) fixed, output power of a flashgun is measured in f-stops (thats why you have a f stop scale on the gun).
Leafshutters on a 4x5 lens just have to be open at least as long as the pulse durates, flashgun pulse duration is in general shorter than the fastes speed on a 4x5 lens shutter.
In real life, using a flasgun, there's always ambient (continues) light, so flash light and ambient light reach the film. As you have selected DOF with the f-stop on the lens, adjusted the flashgun to this f-stop, you now can "play" with the shutter speed: a fast speed will let less ambient light reach the film, a slow speed will more ambient light reach the film. To put it in other words: with the shutterspeed you can balance the flashlight and the ambient light. It can also be done the other way around when it is important that the action is stopped with a fast shutter speed: you select a lower or higher fstop on the flashgun.
On a 4x5 with no metering you need a (flash)lightmeter to check that you do not under or overexpose the film by the combination of flash and ambient light. Some lightmeters are able to show the contrast range in f-stops between ambient and flash.
Hope that this answers your question why there is no shutterspeed dial on the flashgun.
-- Huib Smeets (email@example.com), April 25, 2002.
Shutter speed regulates ambient, f stops regulate strobe. Keep this in mind and you can make any outside picture perfect. If you are shooting in the studio, 1/60, 1/125 is fine. If you are shooting outside, your meter reading will give you an indication what you need to set the shutter for. Let's say you have an ambient light reading of 1/125 @ f11. If you set your flash up to shoot at f16 your flash will be less powerful than your ambient giving you a nice fill. You can cut that back even more to say f22 and get less of a flash ratio. Hope this helps. Scott
-- Scott Walton (firstname.lastname@example.org), April 26, 2002.
Question for Scott Walton: if you set up your flash to be properly exposed at F16 but use F11 on your lens, aren`t you over-exposing your flash by one stop?
-- Roger Lalonde (email@example.com), June 27, 2002.