Does Nikon CLS suck or is it just me? Consistant underexposure

Discussion in 'Lighting Equipment' started by josh_miller|6, Apr 26, 2007.

  1. I have been having problems with my Sb-800 and 600 set up. No matter how much compensation I dial in
    everything comes out under exposed. I can remove umbrellas and point them at my subject from 5 feet
    and they still under expose. If I just set one flash on iTTL it does fine, so it is not a power issue. I use a
    TTL cord to place my master 800 off camera and then use it to control the 600.

    My other problem is that some times in the middle of a shoot the hole system just stops working. I get
    pre flashes, but the flash does not fire during the shutter. I get solid black no flash pics.

    After searching the net I find other people talking about this under exposure problem as well. Does the
    system just suck? should I just give up on TTL and go all manual. I was really hoping to avoid this
    because of speed and ease.
     
  2. Josh: how are you metering? Meaning, CLS is TRYING to help you... but if you change your focal length, move your point of view, use spot focusing and happen to meter off the subject's shiny nose instead of her dark hair, you'll get wildly different results. If you're using matrix or multi-sensor metering and you have a white backdrop, CLS could be thinking that it's just trying to fill in a bit, rather than heavily light the scene. Are you adjusting the per-strobe/per-channel compensation, or the camera's EXPOSURE compensation?
     
  3. Agreed it is TRYING to help you, but I have found that balanced fill flash (BL) can work against you. Try turning it off on the flash.
     
  4. I changing nothing about the shoot. Not shooting a white background. I am adjusting flash
    compensation on flash for each channel.
     
  5. OK, so changing the flash exposure per channel helps with raios between them... but on the camera itself, do an overall exposure compensation, upwards.
     
  6. Wha tf-stops are you working at ? try without the umbrellas. That's right just point them straight at your subject. Umbrellas and softbox absorb anywhere from one stop to 2 or three stops of light.
     
  7. "should I just give up on TTL and go all manual?".... yes. If you want control, take control... t
     
  8. If your pictures are under exposed, so you should get visual and audible warning, and you will know, there is no reason to guess. Make sure the sound monitor is ON, and listen to beeps after exposure, page 89 in the Manual for SB-800.

    Perhaps reading the manual would help ?

    Otherwise the flash will output proper amount of light.

    So, if you do not pay attention to your flash, or do not understand how it operates... so perhaps it is not Nikon CLS...?
     
  9. If your SB-800 displays amount of ender exposure (the display does not last long - so read it quickly), adjust the camera aperture flash by that amount, since the flash already used up all the power it had. Compensating, in case when flash does not have the power to spare, will not do any good for you.
     
  10. "Otherwise the flash will output proper amount of light... I am impressed by the SB800/D200 combo, but I have never found a TTL system that is as accurate, reliable and controllable as a good thyristor-based auto exposing flash unit.
    As for assessing flash exposure by listening for a beep... isn't it too late when the d__n thing beeps? Isn't that more of an apology than anything else? Especially since the very next TTL exposure may be fine, even if you change nothing? I occasionally use CLS and TTL (with appropriate compensation for the specific environment/effect), but certainly not with the flash mounted in an umbrella and never on a paying job.
    Why would anyone want to use TTL flash with an umbrella modified, static positioned flash? Isn't consistent output from a light source what we are after in that situation? Use CLS for a wireless trigger, but determine your power settings for yourself. Facial expressions and body language are too fleeting and impossible to reproduce. The underexposure "beep" is a moot signifier that really means you just lost a moment that you'll never get back... t
     
  11. Lots of questions about technique and all that. Well if can tell you that it is not the flashes
    being under powered, because one shot will be right on and the next underexposed the
    other way around. I can visually check to make sure everything has a ready light before
    firing no difference. I can point with no umbrellas and same results. It is not a lack of
    power issue. It is a consistancy issue.

    Something else I have been noticing during more testing yesterday is that the dam things
    sometimes only fire a preflash. That can even be when I hold the comander 3 inches from
    the sensor on the slave. The main strobe does not fire. I am giving up I think and won't
    waste my time with iTTL for mulitple flash. It works great with one 800 for fast stuff.
     
  12. I do not know why you have problems. I use SU-800 as a commander, and 3 SB-800 as remotes, and almost always get consistent results. Some underexposure happens only if I rush myself before flashes are fully charged.

    I also get consistent results in a dynamic environment when I have 2 assistants helping with remote flashes unually on monopods high above the crowd. The problems I get is when accidentally a flash gets into the picture view, and that can easily fool the metering.

    There could be something wrong with you SB-800 if it is a commander, or with built-in flash if used as a commander, if you insist that your problem is not lack of power.

    Just for a test, set you ISO to 1000, to improve the recycling period, and to make sure that the power is not a problem. Will you also get inconsistent results at ISO 1000 ?

    "I hold the comander 3 inches from the sensor on the sensor" - I believe minimal measuring distance is 0.6 meter. What are you trying to prove by doing 3 inches ?
     
  13. Frank, where can I see some of your work with multiple speedlights using CLS?... t
     
  14. and the reason I ask is while I have seen how well it works in a wide open desert at relatively short range in a carefully constructed shoot (on Nikon's DVD), but I have pro wedding photographer friends who say it does not reliably work in exactly the conditions you just described... a wedding reception, on monopods above a crowd, at even moderate distances (15-30 ft). Thanks for any images you could link up... t
     
  15. You asked about why I was testing them at such close range "what are yo trying to prove?"
    I was trying to make sure that the sensor was absolutely getting the "message"

    I seem to be having the same issues with my gear as your wedding pro friend. Not
    working reliably. Sometimes it works and it works well, other times it does not. I will do
    some testing at different ISO and down to f1.4 but I know it has enough power first off
    because when the flash doesn't have enough power it tells you how much it underexposed
    by. I reguarly use this to figure out how much more ISO I need to allow my flash enoght
    power.
     
  16. That was Frank that asked about "close range" testing. <p>I would suggest that if you are routinely exceeding the power of your flash, that you need to use a more powerful unit. Or re-think the way you make pictures (like your aperture, iso and lens choices)... t
     
  17. It's too bad that Nikon chose to use optical triggers. Radio triggers are better - something closer to Pocket Wizards with all of the CLS control would have been fantastic!
     
  18. and made it a $600 150ws flash unit... t
     
  19. CLS in manual mode works well. Doesnt make sense to use TTL with static strobes although I have tried it and found it to work succesfully. And its all controllable from the menu. Its a shame that the strobes dont have flash receiver sensors on both sides of the body - sometimes my SB-600 wont fire if it cant "see" my pop-up flash.
     

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