Discussion in 'Lighting Equipment' started by chloe_borkett, Nov 6, 2010.

  1. I have a new Viv 283 and I want to know a good process to test the power of the flash and how to determine what setting I put it on for what f-stop. What I mean by this is I only have the veripower adapter now, so this changes the power but I don't know what setting to put my camera on initially - can anyone help?
    Thanks a million.
  2. Well you can find the manual here. Without knowing anything about what you are putting it on, this can e the only recommendation. http://www.butkus.org/chinon/vivitar_flashes/vivitar_flash_units.htm
  3. .. and you think everybody knows what type and model of camera you have ?
    ...since all cameras have some manual exposure control, put your camera in manual mode for exposure and for flash, untill you know better, or tell us more about it.
  4. putting it on? I use a Mamiya 7ii and RZ outfits.
    I'm talking about flash distance to subject - this is what determines good exposure and we all want good exposure, right?
  5. Page 6 of the instruction book linked to by Bob--find the guide number for the film (ASA/ISO) you are using, do the calculation shown. If using the Varipower module, each step down is equivalent to 1 stop, so 1/2 power is one stop down, 1/4 power is 2 stops down (from that calculated f stop), etc.
    I personally make a cheat sheet with the most used f stops, ISOs and subject distances. I tape that to my flash, and can quickly consult it, doing some transposition in my head if necessary. Using some transposition, you can even use the calculator dial on the flash head--think stepping down by stops as mentioned above.
    If you need something more literal, make several 'flash cards' for various ISOs and consult them.
  6. In response to Frank... on the Viv you can take off the knob that controls the settings for distance and F-stop and replace it with a veriable power adapter so you have control over the power output. So I am looking for a test process. But I think I am going to answer my own question and have to do at test at all different distances from half a ft up to 15ft and work through the fstops at all the different distances, process the film and see which distance at what f-stop is the best exposed.
    And btw, I was hoping people who have a Viv would answer as that would make more sense.
  7. Thanks Nadine,
    I didn't realise that's what the veripower was equivelent too, so thanks for the info, makes it way easier.
  8. This might help you too. The subject distance table also 'sorta' works by 1.4x, like f stops. The distances I use for my tables are: 3', 5', 7', 10', 14',20', 25', 30', etc. Again--equivalent to stops (more or less).
    If you own a flash meter, you can also test everything yourself. You will find that most flash manufacturers post 'optimistic' guide numbers. I own a 283 and the Varipower unit. You can see that the dial is not stepped, so it is that much more 'sorta'. :^)
  9. i should still do the test though - so I know what that specfic gun's output power is as as you say the guides are only guides.
  10. Of course, it is always best to test for yourself.
  11. Chloe,
    I tested 2 different units with a Sekonic 558 meter, and found output at 10' to be about f8. In other words, guide# of 80-85. You should test them yourself, though. If you have a digicam, try f8 at 10'.
    You should be close.
  12. The guide number for that flash is 120. It is probably optimistic, but that works out to 15 feet @ f8 with 100 ISO film. I think angle of coverage is equivalent to a 35mm lens on a 35mm camera. I'm not sure what that works out to on the Mamiyas you have, but I would guess either 80 or 110mm.
  13. The guide number for that flash is 120. It is probably optimistic​
    When the Vivitar 283 and 285 were both introduced, my father and his employer bought them for wedding work. They found that it was the only flash which actually put out as much light as the manufacturer claimed compared to the optimistic figures of the others.
  14. Note, Vivitar made two completely different flashes with the 283 model number. The original 283 had been a staple of photographers for years, having auto and manual modes. Some versions of the original 283 had a reputation for putting hundreds of volts through the hot-shoe, which could fry most modern cameras without protective devices to lower the voltage (Wein safe sync and others).
    A year or so ago, Vivitar sold the flash unit to another company (Sekur I think), and this company is now putting out flashes with the Vivitar name, but I would imagine no common history with the older 283/285 flashes. The new Vivitar 283 is a clone TTL flash that is made for different camera brands (i.e. you can buy one that works with Canon cameras, one for Nikon, one for 4/3rds, etc.). I don't think the new 283 has support for being used as a manual or auto flash.
    With the original 283, given that it was made some time ago, the flash might have aged, and may not be putting out as much light as it did when it was first made.
  15. I should mention, depending on whether you have the new or old 283, it will depend on how you need to set it up.
    If you have the new 283, this is completely automatic. The camera and flash have a little dialog, with the camera telling the flash to send out a small pulse (pre-flash) that it then does some metering through the lens (or TTL) to determine how much power the flash should emit, and then the flash emits a second pulse where the picture is taken. The main control you have is to adjust the flash's power so it emits a little more or less light than the camera thinks it should. On some cameras, you can adjust this in the camera. On some flashes, you can adjust it in the flash, and if you can adjust it in both the flash and camera, it typically would be additive. Thus, if you set your camera to aperture priority mode and set the lens to f/4, take a picture, and then set it to f/8 and take another picture, the two pictures should come out roughly exposed the same. I think the 283 has no settings to use the flash as a manual or auto flash, it can only be shot in TTL mode.
    If you have the old 283 (for which the manual link was provided), the only communication link between the camera and flash is the command to fire. The flash had two modes, auto and manual:
    • In auto mode, the flash had a sensor that read light being reflected back to the flash, and you would set the flash to a particular setting, which matched a particular ISO and aperture in the camera. The flash would attempt to cut off the power to the light when it figured enough light had been emitted. This worked in smaller rooms where the light would flash off of the back wall, but it doesn't work as well in large buildings or outside, since flash would not see the bounce back of the light, and essentially dump the whole capacitor's charge. You can change things by raising or lowering the aperture on the camera.
    • In manual mode, the flash puts out exactly the same power level of light each time. If you are firing the flash directly, you would calculate the aperture to be used, by dividing the guide number to the distance to the subject, making sure both the guide number and distance were measured in the same units. For example, if your flash has a guide number of 120 feet at ISO 100 and the subjection is 12 feet away, you would select f/10 for your aperture. On many manual flashes, you could control the power level, which in turn would control the guide number. Another way to figure out the aperture is to use a flash meter. On digital cameras, a third method is to play guess the aperture, by talking a set of shots at different apertures to find out via the histograms which photo gave the write exposure.
    Note, modern cameras ISO is not necessarily the same ISO as traditional auto/manual flashes and handheld flash meters used, so you may want to calibrate your flash to your camera.
  16. Note, modern cameras ISO is not necessarily the same ISO as traditional auto/manual flashes​
    It should be the same. The S in ISO is for Standardisation.
  17. It should be the same. The S in ISO is for Standardisation.
    Yes but...
    The ISO standard 12232:2006 gives digital still camera manufacturers a choice of five different techniques for determining the exposure index rating at each sensitivity setting provided by a particular camera model.
  18. As BeBu Lamar mentions, the rules changed in 2006 when ISO added 2 new ways (recommended exposure index and standard output specification) to calculate the ISO speed to the existing 3 ways from the older standard, and the CIPA DC-004/DC-008 standards that applies to Japanese camera makers pretty much restricts them to using those new ways and not the original 3 methods.
    Here is the wikipedia article on the ISO standard:
    Hence light meters and flashes that adhered to the 1998 version (or earlier versions), need to be calibrated to modern cameras. Just because a camera maker claims something is ISO 1600, doesn't make it what ISO 1600 used to mean.
  19. When testing GN with a flash meter be sure to use a flat diffuser or have it retracted like in the case of the Sekonic meter.
  20. Hello Chloe. Not sure if the work I saw of Prenostrovie is yours or not. In any case nice works if it is.
    Little late for my opinion, but I think that the best, fastest and economical way to do any flash testing with film is to use
    a digital camera as a Polaroid back. A Dslr or point and shoot with hot shoe and manual settings will work.
    With the same values on the digital and film Camara you will have the same image in both photos, so use the digital
    as a Polaroid back until you get use to the flash and you don't need any more the digital as "polaroid back".
    If u never use flash much before it can be frustrating and very tricky to get what you want, it takes times and money.
    Learning the numbers, values etc. going every day to the lab is a pain on the neck. I know.
    The digital proof will speed the learning proses, cost much less and is 100% accurate.

    For the type of portraits that you do, if what you do is what I think you do...heheh.. you will have no problem doing a
    digital test before..


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