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  1. #1
    Senior Member

    External Power

    Does anyone here use external power for their flashes? I just added a YN685 and was curious how external power works.

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  2. #2
    Senior Member
    Challenge Team
    cwgrizz's Avatar

    Re: External Power

    I've never used one, but the 685 can use the SF-18C or SF-17C (Yongnuo) external battery power. Usually it means that your flash will recharge at the fastest rate for a longer period of time. As to how effective that would be, I couldn't tell you. Hopefully someone else will chime in on this.

    D750; D7100; D5300;
    18-55mm f/3.5-5.6 G II VR; AF-S VR 70-300mm f/4.5-5.6 G IF-ED; AF-S 85mm f1.8; Tokina 11-16mm f2.8 (IF) DX II; 200-500mm f5.6E ED VR; AF-S VR 24-120mm f/4G ED; TC14E II

  3. #3
    Senior Member
    LouCioccio's Avatar

    Re: External Power

    The external ones I used were in the Olympus FL50’s (similar to SB 800/900) you still need the AA’s to run the LCD screen but the voltage was stepped up from the 7.2vdc to I think 300vdc+. It shorten the re-cycle time. There are others that use 6 or 8 AA’ that perform the same function. I used them for Weddings and Events.
    Lou Cioccio

  4. #4
    Senior Member
    spb_stan's Avatar

    Re: External Power

    The battery packs for most modern speed lights are just larger capacity, lower internal resistance and some are a little higher voltage. Increasing the voltage is not really needed since they use very efficient boost regulators running in the 90-93% efficiency to change the discharge capacitor used to create a very high flyback voltage when the flash inductor's magnetic field collapses. I have 3 Yn568n II and they recharge between shots quickly. If a set of batteries don't last 300 flashes, you might be using too fast shutter. too small aperture or too low ISO, so full dumps are needed for each shot. I can get 400 shots from 4 enloops. I also have 3 SB900 Nikons which have about the same flash power and beam focusing out to 105mm but the 900s will go as narrow as the field of view of 200 mm. Other models of Yongnuo flashes focus narrow down to 200mm. I never found that to be important in any scenes, if you need narrow beams, using a snoot or grid controls light better.
    One big difference in the SB900 and 568n ex II is that the Yongnou does not complain about rapid full dumps. The SB900 can overheat and shut down right when you need it. External batteries help keep it cooler but the proper solution is increasing the ambient exposure. If you only need 2 stops of added light, for example in a night time wedding reception, you might have to slow the shutter down in manual mode and set the metered ambient to 2 or 2.5 stops underexposed and let the flash and the remainder. That does several things for you. 1, it makes background color saturation better, 2, creates a better balance of ambient and subject flash so it does not have the dreaded "flash look" with hard shadows etc, 3, allows a set of batteries last all day of shooting and finally, allows instantaneous repeat flash shots because the charge rate of the capacitor is non-linear and if the battery only needs to top it up from a 1/4 dump, it is ready to go instantly. a Big plus of using this method with a SB900 is that it does not overheat.

    Unless you are really trying to light a large area, there is little need for full dumps. With these newer cameras, getting an extra stop from bumping up the ISO from 100 to 200 is not very detrimental to image noise. If there is not a lot of fast movement in the background, you can get by with a lot lower shutter speed so the ambient has time to expose the background and get good color saturation and the flash exposes the subject while freezing any movement. In events, I can shoot reliably to 1/10 second TTL BL mode if using Matrix metering, and the foreground subject is frozen by flash and the background looks more natural. The flash and the camera have two independent metering systems, the camera, in Matrix meters the scene, and the flash meters the subject. Works great in any potentially backlit situation.

  5. #5
    Challenge Team
    Super Mod
    RocketCowboy's Avatar

    Re: External Power

    When shooting events, I tend to use the Nikon battery pack with my on camera flash in order to get longer life. Shooting with eight AAs instead of four is helpful. I can use the same Nikon battery pack with both my Nikon and Phottix flash units, but did not see a way to use external power with the Yongnuo 568s that I have.

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