Quick and dirty guide to manual flash photography?

Discussion in 'Lighting Equipment' started by csafdari, Nov 4, 2009.

  1. I am a large format photographer who rarely deals with flash. In-studio, I use continuous lighting. Now I plan on using a vivitar 285hv flash off-camera with a Canon F1 (new) and a Mamiya 7ii and perhaps a handheld 4x5 life a SuperSpeed -- and I have no idea what to do. I do have a Sekonic flashmeter though. So can someone give me a quick run down, for example for a portrait outdoors espcially involving fill light? Not quite sure how to "balance" the ambient v. flash exposure, and whether this is necessary.
    I understand that the synch speed on the canon f1 is 1/90 -- so I have to use shutter speeds that are slower or equal to that. The other cameras of course don't have focal shutters so not an issue there.
    So suppose I want to take a photo of a backlit subject. The ambient exposure is ASA 400, 125 at f/16. I am guessing I put the vivitar on full-power manual mode, flashmeter the shadow, and end up with another exposure setting.
    Then what?
    I'd buy a book but they seem to all deal mostly with TTL flash and digital cameras. Recommendations? And please do not refer me to strobist -- been there.
     
  2. http://super.nova.org/DPR
     
  3. Fill flash with the Vivitar is not complicated. Meter your subject minus the flash, making sure your shutter speed is at or slower than the fastest x-sync speed. Let's say it's f/8 and 1/60th sec. The 285 has concentric dials on the side. One sets ISO and the other selects an aperture. That's usually color-coded. I know it is on the 283. Set the flash's ISO to the same as the camera and select an aperture on the flash that's one stop less than your shooting aperture. in this example you're shooting at f/8,so set your flash to f/5.6. You can do all of this w/out a flash meter. I did for years.
    In your example above, my first suggestion would be to switch to ISO 100 if you're shooting individual head-n-shoulders portraits. That'd get you to 1/60th and f/11. Then set your flash to produce f/8.
    Henry Posner
    B&H Photo-Video
     
  4. Thank you Henry
    I understand that the dials on the side are basically a quick and easy way of doing guide number calculations.
    Two quick questions to help me better understand this:
    1- Why is the flash set to one aperture that's less than the cameras? To allow more light in?
    2- What about on cameras that have leaf shutters? What's the procedure then?
     
  5. Sorry, make Q1:
    1- Why is the flash set to one aperture that's less than the cameras for fill flash? Is that because the flash should be set to provide less than the normal exposure?
     
  6. The flash acts like a fill light while the ambient acts like your main light. The fill is usually one stop less so it moderates the shadows and contrast and retains the three-dimentionality of the face which is not flat.
    With a leaf shutter, you can use any shutter speed which means you can set your camera to any shutter speed + aperture combo and if you then select a flash output one stop less than the aperture, you'll have the same results.
    I did this all the time with a Bronica ETRS and Metz 60CT1.
    Henry Posner
    B&H Photo-Video
     
  7. Safdari,
    The reason for fill flash outdoors is to bring the shadow detail up to an easily printable range with the highlight detail. You always set your exposure for the highlights with traditional metering and then set your fill flash for an exposure that is less than that of the highlight.
    Henry says one stop less, I say at least two less because I think that fill flash that is too close to the same as the highlight range is too bold. Simply put, you see the effects of the flash when you should see only a raising of the shadow value and a catch light in the subject's eyes.
    Test both and see which you prefer.
    Having said that, I will add that I loathe fill flash. I have never yet seen an example that I feel looks realistic. The primary reason is that it always comes from a tiny light source which produces very bright highlights and very dark shadows. It looks artificial!
    So for me, the choice is always either subtractive lighting by using a shade above and to one side of the subject, or the use of a large reflector to bounce a large and soft source of light into the shadow areas of the subject shadows.
    By all means, test each approach and see which fits your preferences.
     
  8. OK thanks - that seems straightforward enough. So just let me see if I got this: by setting the flash to one or two aperture stops less than the cameras, you're "fooling" the flash into producing less light than the ambient light. I suppose the same result could be acheived by setting the flash on a higher ISO?
     
  9. all you're trying to do is fill-in the light and change the contrast between the ambient and flash. if you use the same power rating, it'll look flat and fake. set it to 1-1.5 stops less and you start developing some interesting shape and shadow.
     
  10. Thanks I got the concept -- fill light should be 1-2 stops less bright than ambient lite so as to bring out the details in the shadows but not overpower the ambient light or else you end up with flat, boring overexposed images.
    But now how exactly do I set a particular exposure setting on the vivitar flash? Please tell me if I am doing it right:
    Say my ambient light reading is ASA 400, f/8, 1/250. Taking into consideration that my fastest xsync is 1/60, that comes out to f/16.
    OK now If I want the fill flash to have 2 stops less exposure, I calculate i would have to set the flash on f/8.
    I set the side dial on the vivitar at ASA 400, and see that f/8 lines up to the red tab.
    So I then set the varipower knob to the red setting. Now I should be getting a flash that is equivalent of two stops less than ambient at 1/60. Is this right? Is this how you work it?
    ==
    Oh but somewhere in there I have to take into consideration the distance to to the subject?
    This is confusing!
     
  11. If you study images that win the blue ribbon and images that sell best, a common theme emerges. That theme is an illusion that the scene was illuminated by one and only one light source. Images illumined by one light source, coming from above look natural. Hollywood creates monsters (unnatural) using low and multiple lights.
    Now the scale of film and digital cannot tolerate most one light set-ups. The dynamic range is too great and the shadows are too dark thus void of detail. Our countermeasure is to fill the shadows with illumination. Thus we fill using reflectors or a fill lamp. The idea is to preserve the one light illusion. Ideally we fill from the cameras perspective. Thus the fill is at lens height and close to the camera. The fill in this position preserves the one light illusion.
    Also to preserve the one light from above illusion the fill is adjusted subordinate to the main light. One f/stop subordinate gives a 3:1 ratio with is ideal and called the “bread-and-butter” ratio because it sells best. If the fill is set two f/stops subordinate the ratio is 5:1 a more masculine lighting because it delivers higher contrast. If the fill is set three f/stops subordinate the ratio is 9:1 a high contest theoretical presentation.
    You should practice 3:1 – 5:1 – 9:1. Keep in mind photography is both an art and a science. There is no law that says you must follow these recommendations. Likely the artist in you will tell you this is gobbledygook.
     
  12. One more point: The magic number to control light from a flash is 1.4. This is the square root of 2 rounded to one decimal place. The inverse of 1.4 is 0.707. These values are the keys to the kingdom.
    To reduce the intensity of light at the subject plane, measure lamp-to-subject distance. Multiply by 1.4. The results is the revised lamp-to-subject distance that reduces the energy received at the subject plane by 1 f/stop. Conversely multiply 0.7 and this revised distance increases the light at the subject plane by 1 f/stop.
     
  13. Thanks Alan - great exposition of fill light.
    I get the concept however not quite sure how to execute the concept using the settings on this flash.
    Like I said, I am a LF photographer who doesn't use much flash. Being used to the rigor of the Zone System I find it disconcerting to rely on the dial on the flash especially since I am told that it can the inaccurate due to factors such as the environment (size of room, reflective qualities of surfaces, etc.) so I have the urge to rely on flash meters to try to control everything. But in reality I can't use flash meters all the time.
    The problem I'm running into most is that due to the prevalence of digital photography, most of the tutorials and instructions out there have a trial-and-error approach. After all, to them its just a bunch of electrons.
     
  14. Sorry you couldn't find your answers on strobist this is a very good site for flash photography. The Canon F1 is a 1970's camera and your learning with that and the medium format cameras will be expensive in your film purchasing and development costs. To save money and time I would recommend going on E-bay and buying yourself a cheap Digital SLR. I sold my digital rebel for $150 bucks and will sell my Canon 30D for about $350. In any case even a first edition digiatal SLR will have comparable featues to the F1. The benifit is you can practice to your hearts content and get immediate feedback on what each setting does with your flash. Otherwise you will need a notebook and take notes of each shot so that when you get your film back from processing you can coorelate the flash / camera settings to the results on the photos.
    Personally, I don't like fill flash. I like for my flash to look more like my main flash in studio so that the subject is at least 1 stop brighter than the background. I meter for the background and set camera to 1 to 2 stops under exposed for background and ambient light. I then use my flash at exact reading for model so that I am not under or over exposing the main subject. This will make colors in the background pop more and not be washed out.
     
  15. Guide numbers to the rescue:
    Check your manual to discover the published guide number for your unit. No luck then, with the subject set at 10 feet, and the ISO set to 100, shoot a series at f/22 – f/16 – f/11 – f/8 etc. Select the best one as to exposure. Assuming f/22 then multiply 22 x 10 = 220 this is the guide number for 100 ISO. For 200 ISO its 220 x 1.4 = 300 for 400 ISO its 300 x 1.4 = 430.
    Now pictures of people using the Ansel Adams zone system, you place the skin tone at zone VI. This is one stop more exposure than the tells you because the meter is calibrated to deliver zone V a battleship gray that is too dark for skin tone. Using sunlight as the main, use your reflection light meter, read the skin tone. Assume reading is f/22 a zone V value thus too dark. Now open up 1 f/stop to f/16 to achieve zone VI. This is the aperture setting to be used for this shot.
    To match the flash with the sunlight we calculate: Guide # ÷ f/number thus:
    220 ÷ 22 = 10. This is the distance in feet lamp-to-subject that delivers the flash to the subject with the same intensity as the sunlight. If both main (sunlight) and fill are the same, the ratio is 2:1 too flat. We want the flash subordinate by one f/stop so we multiply distance x 1.4 to calculate a revised distance to create a flash 1 f/stop subordinate. Thus; 10 x 1.4 = 14. Setting the flash at the 14 feet mark delivers the desired 3:1 ratio.
    Guide number usage has many pitfalls. Guide numbers are typically established in a room with the usual wall and ceiling height and color. All prefer using a light meter. Also the modern flash and camera with chip logic can outperform all this math and guesswork. However if you look at this stuff with an eye to learning the root basics you will better understand the concepts OK its just gobbledygook coming from an old man.
     
  16. hi safdari, i am also a large format shooter, the flash i use is a nikon sb800, after reading the ambient light i set my camera and flash to the same aperature, then i use a laser rangefinder that i picked up at the hardware store to measure my distance, i then power down my flash to equal or come close to the distance that my rangefinder says, from there i close down my flash about a stop and a half and shoot, seems to work pretty well. I think the vivitar 285 will power down.
     
  17. For years when I used my Vivitar 285HV outdoors I just set the circle wheel on the side which has illumination button, to the yellow mode position after inputing the other settings. Covers a wide range of distance, most of the time....Once in a while to the blue position. Never to red..I think or so I recall....And I seemed to get the right amount of flash fill, but of couerse I like a decent amount of fill to get rid of noonday shadows. I know it sounds dumb, but a successful wedding photographer at a workshop told the class he always used the yellow mode on top of his Hassie with Vivitars. )
    Who cares how it works, I mean if it just controls a little aperture inside the thyristor flash. (What works , works, as you will agree and expereiment is not so bad a deal with one test roll.) Once you get a feel for yellow / blue mode you will likely maintain those distances and film speed for the rest of yo' natural life. Am I correct? Your groups will usually be a similar distance to the camera.
    Guide numbers, phooey. Strobist I can't say, too old for strobist methinks. One roll for trial at different side wheel color settings ought to do it. Ambient first of course with an incident reading at subject, flash must look right to you in the print...make a note on each shot what you used...Too simple? Take a flash reading for the fun of it at the mode you choose and see what it gives you...I bet it comes out fairly decent vis a vis less than key light....which is your sunlight source...most of the time anyway.
    True, but remember this: Negative film has considerable latitude for goofs like us..I do wish you the best. If you find that you need to power down the flash, you power it down. Laser rangefinder? John Golden, you are a wickedly scientific guy...I love it. ( In the Navy we used to paste settings on a little card attached to the back of the flash. High tech then.)
    Important addendum. It was a delightful revelation that I did not- repeat- did not have to go to flash's manual mode to get good fill on the Vivitar. Use the auto modes because they work outdoors too, so easy you won't believe it....trust me.
     
  18. Alan, thanks for the multiplier. As a non math guy, how about just using as distances the aperture numbers, 1, 1.4, 2, 2.8, 4, 5.6, 8 etc. as feet? Think I have seen someone recommend tying knots in a piece of string at those intervals for the diy ers. Tim is thinking outside the "lets add more lights" box. He has me carrying a multi tasking piece of real black velvet to use for the subtractive lighting, to tape up as a backdrop or for posing on or just sitting a clean model on a dusty spot. It also provides cushioning in my case.
     

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