Welcome to the forum!

As an adjunct to the Tangents blog, the intention with this forum is to answer any questions, and allow a diverse discussion of topics related photography. With that, see it as an open invitation to just climb in and start threads and to respond to any threads.

is my sb910 malfunctioning?

NaftoliNaftoli Member
edited January 2012 in flash & lighting
if i put my sb910 to full power in the hotshoe then change shutter speed up from 1/125 to 1/160 the efective flash distance becomes less, example put i put my sb910 on my d7000 set manual flash to full power set camera to manual 1/125 of a sec, flash readout tells me 66 feet, if i change my shutter speed to 1/160 flash reads 60 feet, 1/200 and so on and it does this even if i hss is turned off
Tagged:

Comments

  • i called up nikon they were clueless
  • at full power at 1/200 i get more power from my sb700 then my sb 910!!?
  • i'd send it back and tell them to either fix it or replace it. i was a big Nikon fan until a D2X fell off a pew onto a carpeted floor. cameras are like a slice of bread with butter, always fall face down. it wouldn't focus correctly. after the third return i received a phone call informing me not to return it again. no problem, Got Canon?
  • gonna go exchange it for a new one in b&h tom
  • so i went to exchange it and i tried out the new one in the store it had the same problem it seems like all sb910s r messed up
  • in image #1 the sb910 is indicating 16 feet,in image #2 as u can see i only changed the shutterspeed to 1/250 of a sec, and now the flash reads 12feet,in image #4 i didnt change any settings i just put my sb700 in the shoe and it reads 13feet compared to 12 feet on the sb910image
    1.JPG 173.9K
    2.JPG 182.2K
    3.JPG 178.2K
  • TrevTrev Moderator
    edited January 2012
    naftoli,

    I am presuming that you had the same ISO reading throughout, I see by the embedded image it was ISO 200.

    In you initial post, you did not mention ISO, and the ranges you had were around 66ft so am presuming your aperture for those was wider then f8.0?

    I just tested my SB900 [not 910], at the settings you had in the last post and got different results from yours.

    Settings: ISO 200, f8.0; SB-900 Flash set to M 1/1.

    Shutter speed from 1 second all the way up to 125th sec, NO change, got reading of 25ft.

    Shutter speed 160th - 23ft; 200th - 21ft; 250th sync speed - 19ft; 320th FP mode, - 11ft; 400th - 10ft; 500th - 9.2ft; 640th 8.2ft.

    Your readings of ISO 200, f8.0, 125th of 16ft is a hell of a lot less than mine of 25ft.


    Wait a minute, I just noticed, the ZOOM, it's at 18mm....

    Check the zoom, mine was at 70mm for those readings... when I went to widest on my lens, 24mm, it dropped to 15ft; 10ft difference.

    So I think it's because you maybe changed zoom setting, accidentally or not.

    Test at full zoom in for your particular lens.

    I don't think there is a problem with the flash per se, unless you can replicate the same readings at same zoom.

    Trev.

    Edit: I had to open my aperture to f2.8 to equate flash M 1/1, ISO 200, Shutter 125th, zoom 70mm for my lens/camera combo to match the 66ft you mentioned in your first post.
  • hi trev thanx for trying to help me out, yes in my initial post i was around 2.8 iso 400 sorry not sure if the numbers in my first post were 100% accurate as i did not have my camera in front of me at that moment so i was writing from memory however the concept is the same.

    On my jan. 11 post all settings 100% accurate (unless you can replicate the same readings at same zoom.)
    my flash zoomed out to 18mm set to normal illumination mode,camera set to M at f8, ISO 200, as u can see on the atachments, i dont understand how u got 25ft though, mabe u were set to spot illumination,

    so u did see that the power goes lower when u move from 1/125 to 1/160 whats up with that, what does that mean? on my sb700 i dont start losing power till after 1/320 on my d7000
  • TrevTrev Moderator
    edited January 2012
    Naftoli said: my flash zoomed out to 18mm set to normal illumination mode,camera set to M at f8, ISO 200, as u can see on the atachments, i dont understand how u got 25ft though, mabe u were set to spot illumination,
    That's because my camera's lens was zoomed in to 70mm, not the flash as it followed the lens zoom on auto, I had lens zoomed in fully to 70mm [using 24-70mm f2.8 lens] and therefore my flash was at 70mm, not 18mm as yours was.

    Once you zoom your lens and flash zoom is set to follow/auto it will change power of course.
    Naftoli said: so u did see that the power goes lower when u move from 1/125 to 1/160 whats up with that, what does that mean? on my sb700 i dont start losing power till after 1/320 on my d7000
    Don't know. I just did a new test on mine.

    Flash SB-900 M1/1 but this time, I deliberately had flash [not camera] set on full 200mm Zoom, not to follow the lens, and no matter what shutter speed up to sync speed I changed to, or what I zoomed the lens to, the result stayed the same.

    20m [20 meters is equal to 65.62 feet]

    The moment I went from sync of 250th to 320th, it dropped dramatically as expected to 12m [12 meters is equal to 39.37 feet].

    Camera D3s, ISO 200 f2.8

    Trev
  • ok so to duplicate my setup u can just zoom the flash out to 18mm no matter what lens is on the camera, the reason i think ur flash didnt seem to loose power when changing from 1/125 to 1/160 when u zommed it to 200 mm is b/c i think the ur flash isnt capable of displaying that it can go more powerful than 20 meters, so when u zoomed in 200mm it was really going further than 20 meters and when u used faster shutter speeds it didnt show a loss of power b/c it was still more powerfull than the 20 meters that it reads
  • AllenAllen Member
    edited January 2012
    This is from page C-17 of the manual (downloaded from nikonusa.com):

    "In default setting, the flash compensation step between 1/1 and 1/2 is ±1 EV
    step. This step can be changed to ±1/3 EV steps in the custom settings (B-17).
    With some cameras, and when using higher shutter speeds with a flash output
    level higher than M1/2, actual flash output may decrease to M1/2 level."

    There's no explanation for either of these, but if you reduce the power to M1/2, does the distance still decrease when you increase the shutter speed?

    P.S. The answer might be in Nikon CLS Practical Guide .

  • Neil vNNeil vN Administrator
    The SB-900 does the same thing. Instead of the display showing the output remaining constant until you hit max sync speed, and THEN only dropping off ... the output starts to slope from 1/160th onwards.

    I have no explanation for it. I doubt the actual exposure is affected. (I haven't tested for this though). So I do think it is just some algorithm in the flash itself doing this .. for whatever reason.

    The one thing I hate the flash doing this, is that it totally messes up my explanation in workshops, of what happens at and beyond max flash sync speed.
  • Neil vNNeil vN Administrator
    in short ... your flash isn't faulty.
    It's just an inexplicable quirk of the SB-900 and SB-910.
  • AllenAllen Member
    edited January 2012
    Neil, Russ MacDonald makes a good job of explaining it in the link I posted, above. At full power the flash pulse is longer than the exposure duration, so you're cutting off the tail of the flash. If you use a longer exposure or lower power, you don't.

    http://nikonclspracticalguide.blogspot.com/2009/03/15-when-is-full-power-flash-not-full.html

    P.S. The D700 manual states that if you use 1/320s (Auto FP), the flash range drops as shutter speed increases.
  • StephenStephen Member
    edited January 2012
    The D700's specification says that 1/250 is its flash sync, so setting it to 1/320s (auto FP) only seems to be helpful if you want the pop-up flash to have the same flash sync speed (there is a chart on page 306). I have been fine with 1/250s Auto FP.
  • I've just re-read Neil's own test on this very subject:
    http://neilvn.com/tangents/2010/08/02/high-speed-flash-sync/
    ...Don't you just love it when the theory doesn't match the practice, lol!

  • allen thats what i was thinking, but if that were true then that means that my sb700 is more powerfull than my 910 at max sync speed at half the price!
  • unless the sb700 is not telling me im loosing power when i really am
  • It'll be interesting to read the result of the comparison test you're about to do:)
  • uhh was kinda hoping neil would do it :)
  • Neil vNNeil vN Administrator
    A simple test then.
    (I used a D3 and SB-900)

    - Set your flash to 1/1 manual power.
    - Bounce it behind you.
    - Focus on a white object in front of you.
    - Use 1/100 shutter speed.
    - Find the aperture at which the exposure is correct. (using the histogram)
    - Now step your shutter speed for repeated shots, making sure your flash recycles completely.
    - Now check if the exposure drops between 1/160 ... 1/200 ... 1/250

    I didn't think it would, but it does ...
    it drops by about 2/3 stop between 1/160 and 1/200
    and another 1/3 stop between 1/200 and 1/250

    I can't explain this. (yet)
  • Neil, this guy russ macdonald seems to really know what hes talking about, basicly he says that by using shutter speeds faster than 1/125 then ur cutting off the tail of the flash pulse, another proof is that at 1/1 power 1/250 of a sec the flash will recycle faster B/c it saves the power used at the end of the pulse. according to that logic then my sb700 is also loosing power but just its not telling me,
  • mvheystmvheyst Member
    edited January 2012
    How long is a complete flash pulse for the SB-910? Is there a difference in time between a complete flash pulse of the SB-900, SB-910 and SB-700?

    It was widely reported that the SB-900 had an "overheating problem", and the SB-910 has "Advanced Protection Against Overheating". Is it possible that Nikon could have "streched" the time of the flash pulse to reduce the intensity (or heat) of the flash.

    Is the flash fired at the same time (meaning just after the shutter curtain is 100% open) for all 3 flashes?

    How long does the light of a flash bounce around in a room with white walls? Can the light bouncing around contribute towards the "ambient" light during or after the flash pulse?
Sign In or Register to comment.