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Auto FP flash setting for Nikon D810

sazeracsazerac Member
edited November 2014 in Nikon
In your article   Auto FP flash setting for Nikon D300s & D700, you show that setting Auto sync 250 is best.  I was wondering if you have done anything like that for the Nikon D810?  would the evaluation be close if you have previously did the d-800 or 800e?


  • I would definitely recommend using one of the two auto FP settings and leaving it set there all the time. There is no harm in that. 1/250 Auto FP is safest or you could use 1/320 Auto FP and perhaps risk a slightly darkened edge when you shoot at 1/320 as Neil pointed out in the article (which you may not even notice for most shots). You might need to do your own experimentation.

    If you don't use one of those auto FP settings, then you won't be able to use shutter speeds faster than the sync speed you set with option e1. While using high speed sync can have issues (notably a huge reduction in effective flash power), it can be indispensable sometimes.

    (Note this discussion assumes you have an external speedlight which is compatible with Nikon Auto FP high speed sync. The built-in flash and some external speedlights do not support high speed sync.)
  • Neil vNNeil vN Administrator
    Checking this on my D810 now with an SB-900 speedlight, using fixed camera settings and manual flash output: 

    - going from 1/160 to 1/200 to 1/250 gives exactly the same exposure, as expected. 

    setting the camera to 1/250 Auto FP: 
    - going from 1/250 to 1/320 gives a massive drop in flash output - 2 stops of light. 

    setting the camera to 1/320 Auto FP:
    going from 1/250 to 1/320, you now lose only 1/3rd of a stop. 
    eg, if you were at f/6.3 for 1/250th, you'd have to go to f/5.6 for 1/320

    In practical terms, this would gain you 1/3rd stop higher shutter speed - probably marginal an increase for stopping action. The 1/3rd stop wider aperture is also incremental and of no huge importance. However, if you want it, you can have it by going to 1/320 Auto FP. 

    You can easily verify all this for yourself right there in your living room, bouncing manual flash, and checking the histogram for a white subject.

  • Good post Thanksgiving day. I appreciate your answering and posting this incredible series of flash information. I believe I am close to "getting it" for flash. I love just staying in TTL-Bl and learning it. 

    I did your experiment with my D-810 and SB-910 and found one stop loss when I went from 250 to 320 while in 1/250 Auto FP. I had the same loss of 1/3rd while in 320 Auto FP. 

    Now I will make a statement that may prove I really don't understand flash.

    • for only 1/3rd stop loss in 320 Auto FP it probably makes sense to stay in 320 Auto FP as my default camera setting. It allows me that extra 1/3rd of faster shutter speed, although probably not really significant.
    • When I use TTL, I realize that the camera sets the flash exposure, but at least I know that when I choose 320 Auto FP and 1/320 as my desired speed I will be at/near the sweet spot and max power of the flash.
    Interestingly to me, I did the above experiment with 320 Auto FP and went up to 1/1000 and it was only at this speed that I saw some darkness on the right side of image.  As expected there was no change in exposure as I went up the staircase of speeds in TTL-BL

    I am looking forward to getting the rest of your books and reading the blogs. Do you ever do Group Workshops on the west coast (San Diego specifically ).

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