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  1. #1

    Join Date
    Mar 2003
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    I have a question about using a flash unit with my 35mm camera. It's a Nikormat EL, with a synch speed of 125 seconds. The flash unit is a Vivitar 285.

    The Vivitar has a dial wherein I can input up to ASA 400 speed film.

    I want to take some black and white photos of a person cooking a meal inside their kitchen. There won't be any really quick motions from the subject just normal moving around with normal ambient light.

    Questions.

    1. With 400 speed film at 125 will the flash freeze the movement of my subject?
    2. If I used faster film e.g. 1600 should I turn my flash intensity down to ½ or ¼ power?
    3. There is a removable insert over the bulb that softens the flash effect, would that be good to use with the 1600 speed film or with all or any other speed film.

    I want the subject to appear to be lighted naturally rather than harshly as some flash pictures appear to be.

    Any help you can give would be helpful. The shoot is going to take place before I can do any experimenting before hand.

  2. #2

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    Sep 2002
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    1. Yep. The flash duration will be a lot shorter than 1/125.

    2. Maybe, or close the aperture from whatever the flash recommends by the factor of stops your faster film is than 400. In this case 2 (400->800->1600) So if the flash said f5.6, use f11.

    3. It is probably use to spread the light in a wider arc, eg for when using a 28mm lens (my flashgun has something similar)

    4. Bounce the flash off the roof. I think a 285 is powerful enough to do this. Aim the head almost vertical if you're getting fairly close to the subject.

    5. Experiment (options 2-4 really require an experiment or two before using)

  3. #3
    Ed Sukach's Avatar
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    Nov 2002
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    First, the "flash" setting is the "mechnical shutter speed". Both curtains of the shutter will be open at that speed, 1/125th of a second, with the entire frame uncovered. At faster speeds, the entire frame will not be illuminated by the flash.

    Now,

    1. Most probably. I'm not familar with the flash duration of the 285, but usually they are considerably faster than 1/125 of a second. I could be wrong, but I cn't think of *any* single-flash units that burn that long. see Note 1

    2. No. Unless I'm mistaken, the "1/2" and "1/4" POWER settings will be for a "manual" flash setting. The Vivitar 285 is a Thyristor unit - On "automatic" there is a small sensor that will read the amount of light and turn the flash off when a certain amount of light is reflected from the scene. On the "manual" settings, that sensor is bypassed and the 285 will produce 1/4 or 1/2 of the full power of the unit - requiring the old "guide number" calculation.
    The camera is not "coupled" to the flash unit. If the highest film speed setting on the flash unit is 400, and you are going to use 1600, set the aperture two stops smaller. If the setting on the flash for ISO 400 is f/8, leave it there and set the camera aperture to f/16. You may run out of room here, depending on the smallest aperture available on the camera - then, about the only thing I could think of would be a 2x neutral density filter over the lens.

    3. The attachment that goes over the flash tube is a "wide angle diffuser", that spreads the light from the unit for use wth wide angle lenses, and "softens" the light - while lowering the output somewhat.

    4. There are one or two "tricks" to soften the light. One is to drape an ordinary handkerchief ove the flash tube, being careful NOT to cover the Thyistor sensor. You could also "bounce" - I think the flash tube on the 285 can be swiveled up through a 90 degree arc. Point it at the ceiling with a bounce angle of 45 degrees. That should scatter the light enough to minimize the harsh shadows associated with "straight-on" flash.

    Note 1: For all the "Techies" out there - Yeh, I know of the Olympus "T" flash units... they are not "single flash" units - they are really "pulsed".
    Carpe erratum!!

    Ed Sukach, FFP.

  4. #4

    Join Date
    Mar 2003
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    28
    Thanks a million guys. Fingers crossed and here goes!

  5. #5
    blansky's Avatar
    Join Date
    Nov 2002
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    Peter:

    I'm not sure why you want to use film other than ASA 100 or there abouts unless you are wishing to have a grainier look.

    The other thing is bouncing the flash off the ceiling is still not a very flattering or great way to photograph someone. If you have a cord for the flash instead of a hot shoe (camera mount) you will get better pictures if you can mount the flash on a stand a few feet to the left or right of camera and slightly higher. Then as suggested, diffuse it a bit.

    If you're unsure of the output, bracket the flash instead of the camera. (That is change the flash setting on identical shots they pick the best one in printing)

    You also didn't mention if you are blending the flash with ambient light coming on from windows, in which case the flash would only need to be an accent light.

    Also if you have time, get a subject and fake the whole thing beforehand to identify what you need to do. Print those shots then when you do the real shoot you can concentrate more on the subject and less on the equipment

    MIchael McBlane
    I couldn't think of anything witty to say so I left this blank.



 

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