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Can you explain this? Flash photography & exposure

keano12keano12 Member
edited May 2015 in flash & lighting


I was watching this video on YouTube by Zach Gray.  

What I don't understand and others mention it to is that he underexposes 1 stop at F11 for the sky. Yet sets the flash for F11. Shouldn't the flash be the correct exposure 1 stop above?

Comments

  • Neil vNNeil vN Administrator
    edited May 2015
    What doesn't make sense is that he starts with his shutter speed at 1/100 
    That isn't optimal for flash when battling bright light. We all know that by now. 

    Also, the way he meters, pointing his camera at the sky ... and then dialing the aperture down by another stop, and then claiming it is 1 stop under-exposed ... doesn't follow a specific thought-process or algorithm for exposure metering. 
    "f/11 gives me -1 stop sky". Yeah ... that doesn't follow a specific logic in terms of tonal placement or exposure metering. 

    If it had been a bright blue sky ... then what?  Or partly cloudy? Then what?


    But back to his insistence on 1/100 as his shutter speed, because "that is what I shoot most of my strobe stuff on" ... that just riles me. There is no reason for that. None that he explains, anyway. 

    The actual technique to then meter for his subjects at f/11 is about the only part that makes sense. (And choosing 100 ISO in bright conditions.)

    There are two problems with his choice of 1/100 shutter speed. 
    a.) he runs his flash at a stop more power than is necessary, compared to him being at max sync speed of 1/200 (or 1/250)
    b.) 1/100 could run the risk of camera shake. Flash might not freeze any movement when the flash exposure and ambient light is close to each other. 

    Summary: I wouldn't recommend or use his "system".
  • ViccoVicco Member
    ooh-key. Hmm, as everyone, who learned from Neil, I can spot the technical issues in that video quite easily. :-)))

    Sure, normally you would set the cam on its syncspeed, like Neil says (1/200 or 1/250).
    As I use the cheap and slow chinese RF trigger brand with the "Y", I have to give that a bit of headroom, and I'd would set the cam to 1/160 second.

    And then I would set the ISO as low as possible, to get a deep and cool underexposure, without stepping down the lens to f/11 or f/16 (which is quite far from the so-called critical aperture). With my cams (5d2, 5d3) this is ISO 50. Modern Nikons can afaik go down to ISO 32.

    One stop underexposure for the ambient seems ok, although I often end up with more like 1,3 or 1,7 stops.
    Regarding the question in the first comment: well, as far as I understood that, he just peeks through the viewfinder and adjusts that measurement scale there via dialing down the aperture, until he reaches -1 EV. That seems ok. His usage of the lightmeter seems also ok, as he set his cam to f/11, and so he has to adjust the light to fit f/11 to light his subject properly.

    BUT .... the worst thing about that little tutorial is, that he obviously uses an ND filter on his lens.

    This makes sense, as it allows him to open up the aperture and to get a soft background (as can be seen in the shots) without violating the xsync limit. But he just does not mention that.

    And so, all the f/11 babble is just completely pointless. :-)))

    Cheers,
       Vicco






  • keano12keano12 Member
    thanks for the feedback guys!
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