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Thread: SB900 or 910 to help with AF assist?

  1. #1

    Default SB900 or 910 to help with AF assist?

    Hi guys, i have a problem here, yesterday I was helping to shoot my friend's BBQ party, and the place was quite dark, so my d7k was focus hunting the faces.

    I tried turning on the AF assist lamp to help, but to my horror, it only works with either auto area mode or single point mode with focus point at the center. The problem with this is that i was trying to use pop up flash to expose their faces correctly, and with the auto area mode, the camera usually dosent choose to focus on their faces(it likes to focus on the clothes instead), so the faces keep getting underexposed.

    I have been thinking of getting a flash, and i thought i might get a sb900 since it has af assist lamps. However, upon more reading, comparing the sb900 and sb910, sb900 has "af assist illuminator" while sb910 has "af assist illumination for multi point AF".

    Could the sb910 be what I need instead of sb900(ie the assist illumination for multi point AF on sb910 will let me choose the focus point I want, and help to focus at that point)?

    or can someone explain the differences between these 2 af assist illumination in the speedlights? pls advice, thanks(:

  2. #2
    Member technoglitz87's Avatar
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    Default Re: SB900 or 910 to help with AF assist?

    Quote Originally Posted by xecro View Post
    Hi guys, i have a problem here, yesterday I was helping to shoot my friend's BBQ party, and the place was quite dark, so my d7k was focus hunting the faces.

    I tried turning on the AF assist lamp to help, but to my horror, it only works with either auto area mode or single point mode with focus point at the center. The problem with this is that i was trying to use pop up flash to expose their faces correctly, and with the auto area mode, the camera usually dosent choose to focus on their faces(it likes to focus on the clothes instead), so the faces keep getting underexposed.

    I have been thinking of getting a flash, and i thought i might get a sb900 since it has af assist lamps. However, upon more reading, comparing the sb900 and sb910, sb900 has "af assist illuminator" while sb910 has "af assist illumination for multi point AF".

    Could the sb910 be what I need instead of sb900(ie the assist illumination for multi point AF on sb910 will let me choose the focus point I want, and help to focus at that point)?

    or can someone explain the differences between these 2 af assist illumination in the speedlights? pls advice, thanks(:
    So then...have u tried with single point focus yet? I've been using that and rarely ever use auto area mode.

    The AF-Assist lamp is only there to provide illumination for faster focusing, the light on flashes are doing the same thing, only in red color variant. It'd be strange to get a flash just for the assist illuminator.

    I turn off all assist light, its too distracting and irritating to some.
    D7000/ MB-D11/ SB-700/ Tamron 17-50/ Sirui T1204x

  3. #3
    Moderator daredevil123's Avatar
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    Default Re: SB900 or 910 to help with AF assist?

    The AF assist in SB900 and SB910 works the same as the built in AF assist lamp.

    You might want to buy a snall led light for focusing purposes.

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    Member sf_kang's Avatar
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    Default Re: SB900 or 910 to help with AF assist?

    Hi TS, I have been shooting with many different Nikon DSLRs and Nikon Speedlites for many years. Here's how I would set up and shoot during the BBQ.

    1. I set the AF to single point (as I always do; this is my default setup as it gives me best control as to where I want to focus. In this case, I'd aim the focussing spot on the face of the friend I want to capture. Noting the the guys face may be dimly lit, the SB900's focus assist 'red' light will temporarily illuminate the face, and the camera will focus immediate I press the shutter button HALF WAY DOWN AND HOLD IT THERE TO LOCK THE FOCUS.

    2. I then recompose the picture while still holding the shutter button half way down. Then when I have finished recomposing, I press the shutter button all the way and fire the flash and take the shot.

    3. This method will ensure that the face is exposed correctly (since you first focussed on the face and the camera to face distance is already captured when you depressed the shutter button halfway.

    I have found this method extremely reliable, always get the shot correctly exposed, and always get the subject's face in focus. AF mutli point is simply too slow and unreliable for this kind of situation.

    Hope this helps.

    Fred

  5. #5

    Default Re: SB900 or 910 to help with AF assist?

    hi guys, thanks for all your replies and i appreciate them!

    but i need to clarify some things first:

    1. i always use single point AF, since i want to have control of where i focus.

    however, for that day, i was forced to use auto area AF mode because i realised there were only 2 ways in which the d7000's built in assist lamp would work: (i) in auto area mode (ii) in single point mode, but focus point MUST be at the center. if focus point is moved out of center in AF-S mode, built in assist lamp will not work. since it was hard for me to compose every shot with center focus, therefore i switched to auto area AF mode, hoping for better luck with it.


    2. i usually lave the af assist lamp on d7k off, because i find it distracting too. but that day i had no choice but to turn it on, since it was pretty dark and the camera was hunting for focus.


    3. in any case, im getting a speedlight. now my problem is that i dont know which speedlight to choose,

    because ive read about sb900 having just an "AF assist illuminator" but sb910 having an "AF assist illumination for multi point AF", i want to know if sb900's af assist illuminator will work in single point focus mode, with any focus point chosen? better yet, can someone explain the differences between the 2 af assist lamps in sb900 and sb910?


    if sb900's af assist illumination is only going to work for auto area mode like the d7k's af assist lamp in the dark, then i see no point in getting it. but if it works for AF-S mode regardless of which focus point you choose, then why would sb910 have a different description from sb900 for the AF assist illumination part?

    thanks!

  6. #6
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    Default

    Why dun you make a trip down to Nikon. And give the flash a try. I find hands on is much better the words. And you can see the result. And there always someone there to help if you can't get what you wan.
    nikon D300sl MB-D10 l AF-S VR 24-120mm f/3.5-5.6G IF-ED l AF 50mm f1.8 l Tok 12-24mm F4 l SB900

  7. #7
    Moderator daredevil123's Avatar
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    Default Re: SB900 or 910 to help with AF assist?

    Quote Originally Posted by sf_kang View Post
    Hi TS, I have been shooting with many different Nikon DSLRs and Nikon Speedlites for many years. Here's how I would set up and shoot during the BBQ.

    1. I set the AF to single point (as I always do; this is my default setup as it gives me best control as to where I want to focus. In this case, I'd aim the focussing spot on the face of the friend I want to capture. Noting the the guys face may be dimly lit, the SB900's focus assist 'red' light will temporarily illuminate the face, and the camera will focus immediate I press the shutter button HALF WAY DOWN AND HOLD IT THERE TO LOCK THE FOCUS.

    2. I then recompose the picture while still holding the shutter button half way down. Then when I have finished recomposing, I press the shutter button all the way and fire the flash and take the shot.

    3. This method will ensure that the face is exposed correctly (since you first focussed on the face and the camera to face distance is already captured when you depressed the shutter button halfway.

    I have found this method extremely reliable, always get the shot correctly exposed, and always get the subject's face in focus. AF mutli point is simply too slow and unreliable for this kind of situation.

    Hope this helps.

    Fred
    Fred, in terms of exposure, your method will only hold true if you enabled AE Lock on shutter half press and spot meter (for ambient), and FV lock (for flash).

    If using TTL flash mode, center the subject you want the flash to correctly expose for, FV lock (flash will fire once), once locked, focus again, recompose and shoot. Release FV lock when done.

    If using TTL-BL mode, it becomes a little more complicated, TTL-BL will cause the flash to expose for the AF point with the brightest subject.

    You may want to read more about how FV lock is used in TTL flash:
    http://nikonclspracticalguide.blogsp...alue-lock.html

    ANd for TTL-BL mode...
    Last edited by daredevil123; 7th February 2012 at 08:58 PM.

  8. #8

    Default Re: SB900 or 910 to help with AF assist?

    Well there is this low tech method for focusing in very low light situations that you know will happen before hand. Tap a small led touch light to the lens hood. Switch that on to illuminated subject - then just do as normal. Works for any situation other than in concerts, where you need to be unobserved till you fire off.

    Alternate to using the FV lock - move the active focus point. It also means that unless you subject shifts away, the flash exposure read back should be on the most critical part of the subject. Makes for less flash "exposure errors".
    Last edited by ellery; 7th February 2012 at 09:10 PM.

  9. #9

    Default Re: SB900 or 910 to help with AF assist?

    xecro, the SB900 is able to project different AF Illumination pattern depending on the AF setting. It is a vertical bar for Single Point AF at Centre and mesh for Single Point AF off centre.

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    Default Re: SB900 or 910 to help with AF assist?

    since we on sb910 toipcs, any idea can we buy spare hard-type color compensation filters ?

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    Default Re: SB900 or 910 to help with AF assist?

    Quote Originally Posted by vaxvms View Post
    since we on sb910 toipcs, any idea can we buy spare hard-type color compensation filters ?
    found

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    Default Re: SB900 or 910 to help with AF assist?

    Quote Originally Posted by vaxvms View Post
    found
    care to share your source?
    Equipment: D800|D700|11-16|28-75|105 Micro VR|50 F1.4G|85 F1.8G
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  13. #13

    Default Re: SB900 or 910 to help with AF assist?

    I had this same question, and was able to test out both the SB-900 and the SB-910.

    Basically the SB-900 AF assist only works when you are using the center column of AF points, while the SB-910 AF assist works with all the points as it has two AF assist LEDs which cover a wider spread instead of the single LED on the SB-900.

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