shutter speed

Discussion in 'Nikon' started by joe_cormier, Oct 12, 2011.

  1. On my Nikon D-300s the next shutter sequence below "bulb" is x32o. Can anyone explain what that setting is used for?
    As always thanks in advance, Joe
     
  2. ShunCheung

    ShunCheung Administrator

    1/320 sec is the fastest flash sync speed on the D300S (without going into the FP sync mode) if you are using a Nikon iTTL-compatible flash.
    If you use FP sync, you can sync with faster than 1/320 sec, but the faster your shutter speed, the weaker the flash power will be. An iTTL flash can go full power with the D300S at 1/320 sec.
     
  3. Actually the 1/320 sec is already FP shutter mode, and requires Nikon CLS FP compatible flash.
    The D300S shutter is so good, that in some of them there is no, or not significant light fall-off at the edge with a non-FP flash. (hardly noticeable darker edge).
    How to test: Turn on the camera, and set shutter to 1/320 in manual or shutter pirority, and then raise the built-in flash, and you will immediately see on the top LCD screen that the shutter speed was forced to the 1/250 sec. You will need to set menu option bracketing/flash/syncs peed to 1/320FP in order to use the 1/320 speed in the FP flash mode.
    Use the 1/320 with a non-CLS flash like a studio flash, and you could get perhaps minimal dark band already (?).
    With external CLS / FP compatible flash, e.g. SB800, SB900, when you set 1/320 shutter speed, you could not get full power in a single flash blast.
    The max sync speed, in classical terms when both curtains are wide open, for the D300S is just 1/250 sec. The 1/320 sec Nikon advertising max sync speed is just a marketing gimmick.
    Nikon documentation states, that the "flash range drops" on page 282 under the 1/320s (Auto FP) chapter in D300S manual.
     
  4. Frank:
    I noticed that same language in my D7000's user manual when I was surprised to learn it synced at 1/320th. Yes, a bit of marketing-inspired product definition, and a bit misleading--its true X-sync is actually only 1/250th.
     
  5. Frank is correct. The 1/320s only works with dedicated Nikon flash. When I shoot with my monolights or even older SB-28 units, I can only get 1/250s sync.
    Kent in SD
     
  6. ShunCheung

    ShunCheung Administrator

    As I pointed out earlier that you need a Nikon iTTL flash to get that 1/320 sec sync speed. However, I was under that wrong impression that at 1/320 sec it was not in the FP mode yet. It looks like the true sync speed is 1/250 sec and at 1/320 sec, you are already getting some FP effect with slightly reduced power.
     
  7. Frank, you keep trotting out this "warning" about the 1/320th top synch speed on the D300 and D700 being an FP mode. Sorry, but it's absolute nonsense.
    The X-1/320th speed gives true fully-open-shutter synch, and IME works with any flash, either hotshoe or studio strobe. In any event, FP synch is a function of the flash rather than the camera. FP mode with electronic flash means that the flash output becomes a true "strobe" consisting of a series of short flashes over an extended time, rather than one quick burst. That's why full output isn't available in high-speed FP mode. It has nothing to do with the shutter cutting off part of the flash.
    Kent, I suspect the issue with your studio strobes is that you're habitually using radio trigger devices. The time delay with most radio triggers prevents the top synch speed being used. For example, I have to drop the synch speed to 1/200th when using my radio triggers since they introduce a delay of 700 microseconds; it's this delay and not the camera shutter that's the issue. With direct cable synch from the P-C socket or hotshoe or by using simple optical slaving you should find that 1/320th becomes fully useable.
    To prove the point, the shot below is a snap of a computer monitor taken with a D700 at 1/320th and f/11. The flash used was a Canon 540EZ speedlite in manual mode at 1/32 power, giving an extremely short burst of light. This is a film-era flash that doesn't support FP mode, and being made by Canon it certainly doesn't support i-TTL or CLS. In other words, when fitted on my D700 it's manual only with no automation whatsoever.
    You can see that the frame is fully exposed right to the bottom with no discernible flash cutoff, and you can verify from the EXIF data if you wish that the shutter speed was indeed 1/320th of a second. The EXIF will also say "no flash" because the camera can't detect a Canon flash fitted in its hotshoe.
    00ZSoP-406391684.jpg
     
  8. ShunCheung

    ShunCheung Administrator

    The difference between 1/250 sec and 1/320 is so trivial that I don't think it is worthwhile to keep debating it.
     
  9. Joe,

    "In any event, FP synch is a function of the flash rather than the camera." - this is absolute nonsense.
    The FP mode is of camera electronics FP mode controlling the flash FP operation. That is why some Nikon cameras have FP and some Nikon cameras do not have FP.
    Another nonsense of yours: "The X-1/320th speed gives true fully-open-shutter synch"

    Nikon never stated that the max X sync was any faster than the 1/2500. The X-1/250 is the fastest sync for D300S, D7000, and only you are trying to rewrite the facts.
    Nikon D300S manual page 387, or D7000 manual page 310 says: "X-1/250" and the 1/320 is already at reduced range.
    Some D300 are capable to provide 1/320 open shutters, but some are not that good. This is the reason why Nikon never claimed the 1/320 speed for X-sync.
     
  10. Then why is the shutter speed below 30 seconds clearly marked "X 320"?
    Shun, I agree that the difference between 1/250 and 1/320th is trivial.
    Frank, the only thing that the camera has to do with FP mode is to signal the flashgun when its maximum X-synch speed has been exceeded. After that the flash electronics do the rest.
    The menu for flash synch on Nikon DSLRs is, I admit, confusing: The "Flash shutter speed" menu option actually sets the longest shutter time allowable by the camera in i-TTL BL mode. In dim light this is the shutter speed that will be automatically selected by the camera when it detects a flash attached, or if the pop-up flash is activated. However in bright light the shutter speed will increase to give a suitable balanced-light (BL) fill flash.
    The "Flash sync speed" menu option sets the maximum synch speed for flash modes other than i-TTL BL. The top two selections in this menu tell the camera when to switch the flash into FP mode. If "1/250 s (Auto FP)" is selected, then the camera will command a suitable attached flash to switch to FP mode when the shutter speed is set faster than 1/250th of a second. However, if this option is set to "1/320 s (Auto FP)" then the flash will only switch to FP mode if 1/400th of a second or faster is selected on the camera shutter. The changover speed from X to FP synch is completely user selectable, and not at a whim of the camera or the flashgun.
    Incidentally, some i-TTL compatible flashguns that don't have FP-synch capability just won't fire when the camera commands them to change mode as above. Although they might still output the metering pre-flash.
    Anyhow, it's very easy to tell if the camera is capable of a true X-synch speed of 1/320th. Set the camera to manual with a shutter speed of 1/320s and hard synch it to a flash set to manual mode. If there's a dark band at the bottom of a horizontal frame - see below, then it ain't got a true 1/320th synch speed. If it's exposed all the way to the edge of the frame then it does have a true X-synch of 1/320th, as I suspect most D300s, D700s and D7000s will prove to have. An overall dimming of the picture shows something else entirely.
    00ZT0e-406565684.JPG
     
  11. Sync speed of 1/320 is indeed significantly different than 1/250, and between 1/250 and 1/200. Yes these are only different to the amount of 1/3 stop each step, but that 1/3 stop is critical in FULL SUNLIGHT, and longer distances, even with sufficiently powerful flashes. Given an ISO of 200 as the best quality with a given camera, and using the flash as fill in sunlight, your solution is 1/200 second at f16 of course. So now you are shooting at an f-stop that is too small for maximum image quality, being that diffraction begins to degrade the IQ of all lenses, at smaller than f8 to f11. If you want the best image quality, corner to corner sharp as in a large group photo with 200 or so faces in the frame, you will need to shoot at f8 to f11 with even the best lenses, re. Nikon 16-35 AFS, or the 24-70 AFS, or even a 24 f1.4 AFS. At f11, you need a sync speed of 1/400. With a native ISO of 1/100 you are better off, being able to shoot at 1/200 f11, but you are still at the upper limit, and if the subject has a predominance of light or white surfaces, and especially true with digital photography where underexposure is way more preferred and repairable, you may require even less light, having to stop down again past f11 into diffraction territory.
    Therefore, the higher sync speed does actually matter resulting in visible quality differences in the the images. This 1/250 second sync limitation is the bare minimum needed. 1/200 is a problem. In the 1980's Nikon produced the earliest FM2 cameras with a 1/200 sync, better than the old 1/125 for sure, but then soon came out with the FM2n and its full 1/250 sec sync. Nikon's D90 has the 1/200 sec limitation, and is replaced by the much superior 1/250 sync of the D7000.
    Now, one thing to mention, and your results might vary, but I don't think so. I have found that my D7000 will actually truly sync fully at 1/320 with any NON-DEDICATED strobe unit, as long as its plugged into the sync circuit directly with no sequential delays from radio slaves etc. Same with both my D300S bodies. The full frame is exposed by the flash at 1/320. Outside in daylight, where the fill flash is working on subjects (to wit, faces) that are not along the very bottom of the horizontal frame, or along either edge of a vertical frame, 1/400 second sync works fine. The fact that there is a small invisible sync-shadow shadow along one edge is completely obviated by the ambient light. At 1/500 second and above, that shadow intrudes too deeply into the frame. One caveat is the maximum flash duration of some powerful flashes. If the flash duration of a strobe is 1/320, then you will clip some of the light power at 1/400 shutter speed. Most flash units are of shorter duration than that anyway, and if you can reduce the power output and still have sufficient light, the duration is even shorter, easily fitting within the 1/400 second shutter sync.
    Try it yourself, if you have access to regular flash. I need at least FOUR times the power of a SB900 and have never understood why Nikon does not produce a dedicated flash of professional strength.
     

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