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Off camera flash

Discussion in 'General flash photography, lighting, and technique' started by Jason, Oct 4, 2008.

  1. Jason

    Jason

    Aug 15, 2008
    St. Louis, MO
    I have been trying and failing on setting up my D300 to fire my SB900 off camera using the pop up flash. What I am getting hung up on is that I do not want the pop up flash to contribute to the exposure...I just want the off camera flash to do this.

    I can get everything to work fine if I use the pop up and let it flash...Can someone please explain the process on how to do this?

    So much to learn...so little time...
     
  2. stayathomedad

    stayathomedad

    Mar 11, 2008
    Alaska
    been there done that...

    under your commander mode you can select what the pop up flash does... if you select it to do nothing, then the only thing it will "flash" is the command it sends to the sb-900...

    so even though you're seeing the d300 pop up "flash"... all it's really doing is the pre-flash...

    Yes, if you do a close up of someone's face you will see the pop up flash in their eyes, but other then that small issue everything is working fine...

    Get the su-800 if it's a big deal...

    and please... someone correct me if I misspoke...
     
  3. Just like SAHD said. When you use your popup flash as the commander, you have the choice of specifying its mode as ttl, aa, manual, or "--". If you select "--", the popup will only fire small command flashes, not something that will contribute to the overall exposure of the picture.
     
  4. Jason

    Jason

    Aug 15, 2008
    St. Louis, MO
    Thanks...one more...

    Thanks for the very quick replies. With that guidance I can now do it! May I ask one more thing? In one of the threads about killing ambient light with the flash settings...I am trying to do that. There is a picture by Medic that showed his daughter reading a book. This was taken during the day with a room filled with ambient light. My wife LOVED that picture and asked why I can't do that! LOL...I said I can do it once I learn how to do it. So that is the type of thing I am trying to achieve here. I am doing this in a indoor room with normal ambient light.

    I will be using my D300 and my SB-900. Can anyone suggest some settings to get me going in the right direction? I will be hiding the flash unit to get that special look. I really appreciate the help.
     
  5. Hey Jason. I'm glad you and your wife enjoyed the pic I posted. It is not a difficult shot to produce, especially with your current setup. All you need to do is set your ISO to 200, and then set an aperture/shutter speed combination that underexposes the ambient light completely. Do this before even turning on your flash. You basically want to be able to snap the shutter, and get a dark frame in return. In other words, use manual exposure, and set it several stops under ambient. Then turn on the SB-900, and set it to wireless CLS mode. Have your daughter hold the book, and just rest the flash against the seam, with the flash head pointing up at her. I had a Stofen diffuser on mine, but don't think it's absolutely necessary. Set your on camera flash to commander mode, and set it to give no exposure input at all, represented by 2 dashes -- Then, it's just a matter of having your daughter act like she's reading the book, and shoot the shot. The SB-900 should be pretty much spot on, but if it's too bright, just set in some negative exposure compensation by going into the commander menu and setting the compensation there. Post your results when you get done. Now, if you want to be able to see the book cover like you do in mine, it requires you to set your camera's exposure so that a small amount of ambient light is registered during the shot. Then, in post processing, you use a levels adjustment layer to bring the ambient light down to black, and just mask out the darkening from the book's cover. Not sure where you are in regards to familiarity with Photoshop, but if you've worked with adjustment layers and layer masks, this should be easy. If you're stumped by that, let me know and I'll go a little more in detail with the steps. Good luck.
     
  6. Here is the shot straight out of the camera. You can see that the book cover is slightly visible. I used a levels adjustment layer to increase the exposure a bit, and then just masked the effect to the book cover. As mentioned above, you can also set the exposure so the cover is a little more visible. If this allows too much ambient light, you can easily do the levels adjustment layer, and pull the middle slider to the right to darken the ambient, and then mask the book cover so it's not affected by that adjustment. The way I did it make the book cover a bit noisy since I was trying to bring the detail back in an area that was severely underexposed. I think you would get a cleaner result if you allowed a little more ambient exposure, and pulled the shadows back down rather than trying to pull the underexposed area up. For reference, the exposure details were D80, ISO 100, 1/400s f/5.0 at 62.0mm iso100 with SB-600 flash off camera. I did have the blinds closed to minimize the amount of ambient light. Since your minimum ISO is 200, then 1/800 second at f/5.0 should get you pretty close to start with.

    original.jpg
    Subscribe to see EXIF info for this image (if available)


    And here is the cropped and slightly edited version.

    original.jpg
    Subscribe to see EXIF info for this image (if available)
     
  7. Jason

    Jason

    Aug 15, 2008
    St. Louis, MO
    Time to try it

    Medic1210,

    Thanks for the reply...we will try that this evening. Soon as my website is back up and running I will be able to post some pictures. It's currently under construction/revamp and should be done in the not so distant future. I will reply via a post on how it went.

    I am a complete "newbie" when it comes to Post Processing. This is one of the areas I need to focus more on and get serious about it. Thanks for all the help.
     

  8. No need to wait on your website to get up and running. Just open a free account with www.photobucket.com and use them to post images. What post processing program do you currently use?
     
  9. WayneF

    WayneF

    Apr 3, 2006
    Texas
    To add to what Medic said, the basic thing to realize about flash is that the flash exposure is not affected by shutter speed, but the continuous ambient light is affected by shutter speed (same way it works outdoors in sunlight).

    So the way to "set an aperture/shutter speed combination that underexposes the ambient light completely" is to first use a fast shutter speed (like maximum sync speed of 1/250 on the D300) to minimize the continuous ambient. Point being, the flash does not care what the shutter is, but using max sync speed is the most you can do to reduce continuous ambient.

    Then the aperture determines how much flash power is needed, and more or less aperture is also a secondary control to determine if ambient becomes insignificant or not. That is, at maximum sync shutter speed, then wider aperture will use less flash power, but also lets more ambient in. A more narrow aperture uses more flash power, but limits the ambient even more.

    But shutter at max shutter sync speed is the first step to keep out ambient.
     
  10. PeterRH

    PeterRH Guest

    Jason,

    if you want to replicate Medic's lovely image but REALLY want to avoid post-production work (for now) yet want to show the book cover in the pic, just follow the steps Medic gave you to drastically underexpose the ambient....but now add a reflector to bounce some light back onto the book cover.

    In Medic's example shown you would use a white sheet of paper/card or anything reflective that isn't a mirror (which can throw up too much light-spill) to the left of the book, facing back toward the book cover/flash-gun.

    Then you need to shoot a few frames to get the effect you want before your children go completely crazy :smile: but avoids you driving everyone nuts trying to work out photoshop/layers 'til you're ready to devote more time to it.

    That's pretty much how I did this:

    [​IMG]
     
  11. Not necessary to keep the shutter speed at 1/250 second. The D300 and SB-900 can sync wirelessly at any shutter speed, just like it can do on camera. Also, aperture does affect ambient exposure just like shutter speed. After all, if you have an ambient meter reading of 1/250 second at f/4, and you close your aperture down to f/8, you're going to underexpose the ambient light by 1 stop if the shutter speed isn't changed as well. But, just like you mentioned, the aperture determines how much flash is needed to expose your child's face.
     
  12. I presume you're talking about FP (high speed sync) mode. Just to elaborate, so can the sb600 or sb800 with any awl camera.
     

  13. Some good advice for sure. One thing that will make this a bit harder with the book is because the flash is inside the book pointing at the child's face, while the opened book cover is actually facing away from the child's face due to it's angle. This will make reflecting light quite difficult.
     
  14. Yep, that's what I used... SB-600 and D80.
     
  15. WayneF

    WayneF

    Apr 3, 2006
    Texas
    Yes, it is necessary. This is a diversion, but there are two huge problems with that.

    1) FP High Speed Sync mode is NOT "flash", instead it necessarily becomes continuous, which drastically reduces flash power, to about 1/8 power maximum. Simply watch the distance scale in feet on the flash LCD as you go from 1/250 to 1/320 second - when it engages FP mode. Flash head on SB-800 must be straight ahead to show distance scale, not in bounce position. Not sure SB-600 has that distance scale. Anyway, FP is not the general way to go because of this loss of power in continuous mode. Unless you are real close, there is nothing left.

    Plus 2) even a bigger problem is that FP is pointless anyway, in this case for this purpose, because the FP flash becomes continuous (required to bypass maximum focal plane sync speed), so then faster shutter speed obviously reduces FP flash exposure too, same as it does any continuous ambient. Watch the distance scale in flash LCD going from 1/250 to 1/2000 second. But this does not happen to regular flash (which is a more instantaneous pulse independent of shutter speed), not until you exceed maximum sync speed to enable FP mode (due to natural speed t.1 duration of the flash being roughly about same value as the sync speed).

    1/250 second is normally plenty to minimize indoor ambient at common apertures like f/5.6. Even shooting close portraits with studio lights, 1/250 second will eliminate the strong tungsten modeling lights (because aperture cannot be too wide then). The modeling lights are a lot stronger on the subject than is normal room lighting, but they are continuous. 1/250 second causes great reduction in any indoor ambient (that less than sunshine). In a normally lighted room at night, 1/60 second will do it too, unless you include the light bulb in the picture - you can see it is on in the picture, but it does not contribute much, at normal apertures. But bets are off at f/1.8. :)  But the shutters max sync speed is better, and no reason not to use it - it is counterproductive not to use it - if blocking continuous ambient is the goal.

    Sorry, not following your point here. Yes, aperture does affect both ambient and flash. But aperture does not affect flash (except continuous FP mode, which is continuous like ambient), so a fast shutter (maximum sync speed) is the very first step of how you eliminate ambient without reducing flash.
    This is a very usable fact to know.

    Sorry too, I dont mean to argue it. Your picture is great.
     
    Last edited by a moderator: Oct 4, 2008
  16. But, for the shot in question, which the OP was asking about, FP is perfectly fine since the flash is so close. To totally render a black scene by overpowering the ambient is a double edged sword. You aren't going to black out ambient at 1/250 second unless ambient is very dim. The only other way to do it is with a smaller aperture, which means more flash power is needed to properly light your subject. Again, for a shot like this, just about any flash will be powerful enough, but to do the same in bright light, you would need a lot of flash power. Again, I was talking about how the shot I made was done, which did use High FP flash.


    Again, my shot was done at ISO 100 at f/5.0. It required 1/400 second shutter speed to adequately eliminate the ambient, so 1/250 second would not have been fast enough. Yes, I could have easily set the shutter at 1/250, but it would have required an f/stop of around f/8. Of course, that's certainly effective, but if the room had been brighter, it would have required even more adjustment. The D300 however (which is what the OP has) only has ISO 200, so he already has to make up for an extra stop of exposure from his ISO, so for my shot, it would have taken about f/16 at 1/250 second shutter speed. Again, not a big deal, but if the room was brighter, you need an even smaller aperture to stay at 1/250 second.

    I think you meant shutter speed does not affect flash, because aperture very much does affect flash exposure.
     
  17. Jason

    Jason

    Aug 15, 2008
    St. Louis, MO
    getting there

    Got to play a little with this tonight. My little girl, who is 2 1/2 years old just was not in the modeling mood tonight. She wanted to play with the flash sitting by her legs as she sat on the floor! Can't blame her...I find myself goofing around with this stuff all the time too!

    I used several different settings and saw how things reacted. I will play around with this more and try and get my girl to do this when I finally get all the settings right. My wife is the stand in for now. Appreciate all the help.

    I forgot to reply about the software I use for PP'ing. I have NX2, and CS2, don't know how to use either one other than the basics :frown:
     
    Last edited by a moderator: Oct 4, 2008
  18. WayneF

    WayneF

    Apr 3, 2006
    Texas
    Sure it does. Ever used studio lights with modeling lights? The modeling lights seem pretty bright, but not for photography. You are not going to get any ambient with 1/250 second at f/8. The modeling lights are many stops down. People even trying to use the 1000 watt continuous so called studio light packages complain they dont get enough at 1/30 second at f/2.8. Those continuous lights work better for product still shots when we can use 1/2 second.


    Sorry to say it, but you seem to not be understanding point 2. If you are using 1/400 second with a FP mode flash, trying to minimize continuous ambient, then you are simply kidding yourself, by obviously not realizing 1/400 (any shutter speed in FP mode) reduces both ambient and FP flash the same amount - since both are continuous in FP mode - same as ambient. Is that understood, or do we need to discuss that specific point in more detail? Again, watch the flash LCD distance scale as you rotate the shutter dial through these speeds. We can observe a lot by just watching. :) 

    FP mode is continuous, same as ambient, acts like ambient, and acts not at all like flash. This is the feature by which it is able to bypass the focal plane shutters maximum sync speed. To prevent the dark bands, it must become continuous for the duration of the focal plane shutters travel. FP mode is no longer flash, it merely comes from a flash unit. This is a very major and huge point.

    ? Regular (non-FP) flash does not care about shutter speed. The shutter speed of 1/250 would NOT affect the aperture that the non-FP flash exposure needed - not in any way. That is the major point here. The flash duration is faster than 1/250, and therefore flash is simply not affected by how much longer the shutter might stay open after it finished. Except (a confusion factor) of course 1/250 causes non-FP mode which would allow regular mode and full power output - and you and the flash certainly would notice that. But the 1/250 certainly does affect the continuous ambient, in the regular way, and which therefore is the primary way to go if the goal is to shut out the continuous ambient.

    Yes, of course, sorry, thanks. It was my turn for a typo. :) 
     
  19. Are you referring to the settings I gave for my shot, or for any shot in general? If you're referring to my shot, then yes, I know that 1/250 second at f/8 would have been the same as 1/400 second at f/5 as far as ambient light is concerned. I said just that in my last post. So, if that's what you were saying, then yes, I agree 100%. I just chose to use 1/400 second instead of stopping down the aperture. No real reason, that's just what I did. Now, if you're saying 1/250 second at f/8 will eliminate any situation's ambient light, then I have to politely disagree.

    Maybe you missed where I set my exposure manually prior to even turning on the flash. I set the exposure until the image was rendered virtually black, thus indicating that those settings overpowered the ambient light. Then, I turned on the flash, and let it do its thing. Obviously the FP mode was enough to render a proper exposure of my daughter. I'm not seeing where the issue is.:confused:  I'm not indicating that FP mode and high shutter speed is the only way to eliminate ambient light. It just happens to be the shutter speed I used at the time. Could I have set it at 1/250 and f/8 to get the same result? Sure. I could have set it at 1/125 second and f/16 too. I know this. I'm not debating this.

    I may be wrong, but I'm pretty sure my SB-600 does not have a flash distance scale. All manual flashes I've used base the distance scale on ISO and aperture. Is this a feature on the SB-900?

    Well, if we're going to be nit picky, then no, FP is nothing like continuous ambient light. It's a very high frequency Flash Pulse (hence the FP designation). It is still, in fact, a flash. It's just not a single flash pop. It's just a bunch of very low intensity flash bursts so close together that it looks like continuous.

    No, but we're not talking about flash output. We're talking about getting rid of ambient, so that the flash is the only light contributing to the exposure.

    Exactly what I've been saying all along. The intent of using the faster shutter speed was to eliminate the continuous ambient light. I just chose to use a faster than 1/250 second shutter rather than switching the aperture to f/8. There are times where you don't want a smaller aperture, but you still need to control the ambient. This is the exact reason the FP mode was made. So folks could still control their ambient light, while keeping an open aperture, and still be able to use flash.

    Now, do you think we can maybe just let it rest before we confuse the OP? He asked me how I did my shot. I told him I used a shutter speed of 1/400 second, which put the flash in FP mode. Was this the best way to do it? Maybe not, but it worked, so I'm not real sure what the debate is all about. I was merely commenting that you did not absolutely need to keep the shutter speed at 1/250 second for this shot, as is obvious by my results.
     
  20. WayneF

    WayneF

    Apr 3, 2006
    Texas
    No, it was not related to the equality of these two numbers. It was in general about the maximum shutter sync speed being the obvious and straight forward way to eliminate the maximum amount of ambient from a flash shot. Of course f/8 1/250 is only about 2 stops less than sunny 16 (D300 ISO 200), and so it obviously is not always even enough outdoors in daytime. :)  And it is not even a dismal faint hope indoors at night.

    Yes, I got that part, and that's good, I do not disagree at all. You want no contribution from the ambient, a very common goal, and that is one way to check it. I was just adding that this trial and error procedure becomes unnecessary if you go straight for the maximum shutter sync speed directly, as being the most you can do towards that end. A smaller aperture increases that effect of course, but aperture affects both, needing greater flash power. Greater flash power is a good tool too, but the max sync shutter speed is the key starting point. Max sync speed limits the ambient the most possible without affecting the flash at all. Simply how things work. Good to know.


    I am saying FP flash mode is a wrong and counterproductive way for this goal of minimizing the ambient. Simply a confusion factor here. Obviously you were able to use greater flash power, but that combination is a real problem since FP mode drastically reduces flash power. FP Mode becomes continuous like ambient, and shutter speed now affects the light coming from the flash, same as it affects the ambient. Then we have no shutter speed tool left to affect them unequally, to minimize one. I was hoping it would be helpful to say so. If this is not understood, then nothing is going to help.

    I suspect you're right about the SB-600. The SB-800 definitely has the LCD distance scale which always shows current range capability (in hot shoe TTL mode), and I assume the SB-900 has the same. You mentioned the SB-900, so I assumed you had one, is why I mentioned the LCD scale.

    So that you will understand what I am saying, on my SB-800 in TTL mode, on a ISO 200 D300 in Manual mode, with e1 menu set to 1/250 second FP mode, then the flash LCD range scale shows this maximum range (related to flash power):

    At 1/100 f/5.6 - range says 3.5 - 39 feet
    At 1/250 f/5.6 - range says 3.5 - 39 feet (shutter speed does not affect flash exposure)
    At 1/320 f/5.6 - range says 2.0 - 17 feet (switches into FP mode - power drops about 2 stops due to the necessary continuous pulses)
    At 1/400 f/5.6 - range says 2.0 - 15 feet ( range drops with shutter speed)
    At 1/1250 f/5.6 - range says 2.0 - 8.3 feet (range drops with shutter speed - like ambient - it is continuous light in FP mode - no longer like flash)

    See what I mean?

    Note that 1/320 second 17 feet and 1/1250 second 8.3 feet is 2 stops of shutter speed, and 1/2 distance is 1/4 power, or 2 stops of power loss - same way faster shutter affects any continuous light, including FP flash. Exactly the same way shutter speed affects sunshine or tungsten (but only in FP continuous mode). See?

    So - your 1/400 second reduces BOTH the continuous FP mode flash and the continuous ambient by the same amount. There is no advantage of that, not for this goal of reducing ambient but not flash. The only tool you have left is to somehow increase flash power, and certainly FP mode is counterproductive to that. This FP mode is just a huge confusion, and it is not the way to reduce ambient and sill allow flash through unaffected.

    Instead - the 1/250 second is the obvious way to do that: 1) it increases possible flash power about two stops by not being in FP mode (is now a much more powerful second tool mentioned), and 2) the non-FP shutter speed does not affect the aperture requirement for flash, but it does strongly affect continuous ambient (may not need the second tool). The 1/250 second maximum sync shutter speed does that the maximum amount that it can be done. And 1/250 second will have an extreme effect on ambient indoors at night.

    In your case, 1/400 is roughly near about a stop faster than 1/250, so it reduced the ambient by the one stop. But it reduced the flash by the same one stop, same ratio, and FP mode reduced the flash power two stops (4x power). The flash must have had enough power to struggle back and overcome (at the close distance), but the goal was to reduce the ambient. Do you see it yet?

    Not picky, simply about truth and right. :)  Yes, FP mode is continuous. It may come from the flash tube, but it is not instantaneous flash, and it does not obey the regular flash rules about shutter speed not affecting flash. It is about continuous light, and shutter speed affects FP mode same as it affects sunlight and tungsten. So in that extremely major way, FP mode is NOT instantaneous flash, or even like flash, it is continuous and acts like a table lamp or sunlight. FP mode loses all distinction between it and ambient. But we have the distinction in the way they work if we stay in regular flash mode.


    Right, and about using the fact that shutter speed does not affect regular flash, but the maximum sync speed shutter affects continuous light in the maximum way that does not affect the flash - which seems key as the way to start.

    I rule out FP flash as a huge counterproductive confusion factor that simply does not fit here.

    But that decision cost you too much. It caused you to give up the advantage of using flash (real flash, unaffected by maximum shutter sync speed), and instead used ambient-like continuous light coming out of the FP flash tube, which is now affected (reduced in intensity) by the faster shutter speed which you assumed helped, but it instead hinders.

    My belief (from Nikon manual) is that FP mode is designed for obtaining a faster shutter speed for fill flash in sunshine. The problem is that we must match the sunshine outdoors (sunny 16), and fill flash is near impossible with a 1/250 maximum shutter. Aperture has to be near the Sunny 16. 1/250 at f/16 requires extreme and unavailable flash power at say ten feet and 35mm zoom. We would prefer maybe 1/1000 at f/8, but the shutter will not sync flash at 1/1000. FP mode does provide shutter speed (allowing wider aperture), but the problem is, FP reduces the flash output so greatly, there is nothing left in most outdoor situations. No easy answer there other than a much more powerful flash.

    Sure, lets let it go. There are better ways, and I tried to explain, and am sorry I failed.

    The one saving fact is that your very close distance may have needed the minimum range drop to 2.0 feet in FP mode. I am aware that I would have a much stronger argument if your flash were at four feet. :) 
     
    Last edited by a moderator: Oct 5, 2008
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