Which film speed is best for outdoors/ambient light portrait

Discussion in 'Medium Format' started by mandi_korn, Jun 10, 2010.

  1. I just bought a Mamiya 645, and the gentleman that sold me the camera has recommended that I use 100 speed film for the outdoors, and I feel as if the results that I have obtained from this film is overexposure. I am using my light meter correctly and the skin tones are beautiful, I just feel as if the backgrounds are extremely bright. My F-Stop was at 11 and my Shutter was.....I think 125 (should have made a log). I guess my real question is "Is the film speed too fast?"
  2. The problem is not film speed, but light control. If you could put up a picture, that would help.
  3. As Luis said, your exposure is accurate. You are just likely shooting in an area with bright backgrounds. I have this problem as well. 400 speed film would just let you shoot at faster shutter speeds, but would not change the exposure.

    You could underexpose to push the background down into the midtones, but that would do the same to your skin tones. For this reason, it's almost mandatory to shoot with flash outdoors. I normally try to shoot 0.5-1 EV underexposed for background, and to add that light back in with flash.
    If you shoot full exposure on flash, you end up with a combined slight positive EV on the subject (flash+ambient), resulting in more separation between subject and background. This gives it a definite "flash look" with the background looking a bit like a backdrop. This can be good or bad, depending on your style.
    I just put up three new photos at my cubical. One was Kodachrome 64 35mm, one was 645 Portra VC 160 negative, the last was Provia 400F slide film on 6x7. Three formats, three film types, three film speeds. All were daylight, all used lots of flash.

    Hope that helps,
  4. I am new to this site, and I am trying to add a photo to the post, but alas I don't think that it is working...
    I am such a silly girl when it comes to photographing with a flash. I do everything to try to avoid using one, and I think that mostly it is because I am not schooled enough on using one outdoors, as much as I am indoors. (thanks to college)
    How do I get to your cubical? Is that possible, since you mentioned it. I just joined the site about 30 mins ago, and have not explored the site fully.
  5. You've only been here 30 minutes, and yet Google finds you here at the top of their listings. Modern technology is amazing. ;-)
    LOL...I was referring to my REAL cubicle. It's that thing you have to look forward to AFTER college. ;-) Even if you were in the Silicon Valley, the security here is pretty tight, so I may have to post them. :)
    I have 4 photos here, none of which are interesting, so I should upgrade them.
    Yes, that's the irony....flashes are lame in the dark, and great in the daylight. I use only bounce indoors, and direct fill almost all the time outdoors.
    As far as I know, there is no metering capability for flash with Mamiya 645 (645AF only). Therefore, you're limited to thyristor controlled flashes if you want any automation, where you set the aperture on the flash to match the lens and go to town.
  6. Early morning or early evening light are best...F5.6 @ 1/125 ISO 400 is about right:)
  7. I shoot without flash as I don't really like that look--well, unless you can really light properly! Nothing sounds wrong with what you did, it just sounds like your setting. If you scan your film, or when shooting digital, there are so many controls to re-balance the image and get it more to your liking. I don't think I have one portrait on my website, shot on location, where I used flash, film or digital, but I do a great deal of work in post.
  8. John and Leslie make some good points.
    Morning and evening light is best because it allows soft front lighting without squinting, and a darker background. (Or conversely, hard backlighting on your subject for hair highlights, with lots of flash. ;-)
    Or, as John says, you can adjust locally within a stop or two without much difficulty in Photoshop. It takes a bit of practice.
    I do like the catchlights that flashes provide, and they can be easily acheived with a small flash...and probably even easier in Photoshop. ;-)
  9. If the person you are photographing is in the same light as the background, one exposure will do. However, if the subject is standing in the shade, there is no "correct" exposure - you have to measure the foreground or the background.
    There are several solutions. If the foreground is important, then expose for that and let the background be overexposed (which you did). If the background is important, then expose for that and let the subject be a silhouette. If you need both, then use a flash. If you don't have or wish to use a flash, find a different background (or place to stand the subject).
    Fill flash is quite simple, even when done manually. Assuming the background is in full sunlight, the exposure will follow the "Sunny 16" rule - at f/16, the shutter speed will be the reciprocal of the film speed, or 1/100. The closest value to this is probably 1/125. That's good enough. By the law of reciprocity, f/16 at 1/125 is the same exposure as f/11 at 1/250 or f/22 at 1/60 (using typical divisions on the shutter speed dial).
    The flash duration is much shorter than the shutter speed. Consequently flash exposure is affected only by the aperture setting. There is one restriction for focal plane shutters. The shutter speed cannot exceed a certain maximum value, about 1/90 for a Mamiya 645. At higher speeds the shutter closes to a slit and part of the frame will get cut off.
    From the guide number for a particular flash and film speed, calculate the desired aperture based on the distance from the subject (aperture = GN/distance). On the camera, find the right combination of aperture and shutter speed to match the aperture needed for the flash. Bingo - a 1:1 ratio for fill flash.
    There's probably half a dozen ways to do this, or any other photographic task. You have to start someplace, though.
    I didn't mention splitting the exposure, or fixing things up in Photoshop. If you "split" the exposure, nothing will be exposed correctly. There are times to compromise on exposure, but not in this example. While you can dodge and burn in Photoshop, it's hard to make up a 3 or 4 stop difference without ugly artifacts. Photoshop (or dodging and burning) should be used to improve photos, not repair them.
  10. From the guide number for a particular flash and film speed, calculate the desired aperture based on the distance from the subject (aperture = GN/distance). On the camera, find the right combination of aperture and shutter speed to match the aperture needed for the flash. Bingo - a 1:1 ratio for fill flash.​
    Edward, I'm following this discussion with interest and do not understand the calculations you are suggesting. Would you mind demonstrating how this calculation works with an example? or more helpful yet, an example with two slightly different scenarios--one in which the foreground subject were 2 stops underexposed, and another in which it were 3.
  11. you're not shooting into the sun, are you? that would definitely make the background bright.
    you didn't mention if you're shooting B&W or color. most B&W seems to be more forgiving -- you can miss it by a stop or two and it won't necessarily look under- or overexposed. nicer, more nuanced skin tones, too, IMHO. different films vary a lot in contrast, too. and finally, you might like the results from more wide open lenses for portraits -- f5.6, f4.

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