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Forums Lobby GET TO KNOW YOUR CAMERA & MASTER IT Nikon D7100, D7000 (Public) topic #3329
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Subject: "D7000 + Auto ISO + Flash = Winner" Previous topic | Next topic
rasworth Basic MemberTue 14-Dec-10 07:35 PM
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"D7000 + Auto ISO + Flash = Winner"


Austin, US
          

The D7000 algorithms for Auto ISO with flash have been "smartened" up a lot as compared to a D300. Auto ISO without flash works well, as far as I can tell identically to the D300, but with flash it's much more effective. The shutter speed almost always bottoms out at the Auto ISO limit instead of the minimum flash speed. And I believe the camera is trying to do some sort of ambient/flash balance, instead of just going for sufficient light. There is a hint or two in the manual, but not much.

My D7000 is set up in Auto ISO, max ISO 3200, min shutter speed 1/160. I shot into my living room, 16-85VR at 16mm, both with no flash and with a SB600 aimed at the ceiling. The attached images are straight out of ACR, default pp - first image is no flash, second with flash, and third a 100% crop of the with flash shot to show noise performance. Both shots were done at f8, the no-flash resulted in ISO 1800, and the flash ISO 1600.

The first image appears underexposed, although the metering system was doing its best to capture the dynamic range of the scene. And in fact a reasonable image can be pulled out with sufficient pp.









Richard Southworth

Attachment #1, (jpg file)
Attachment #2, (jpg file)
Attachment #3, (jpg file)

  

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kytra Registered since 27th Mar 2010Tue 14-Dec-10 08:10 PM
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#1. "RE: D7000 + Auto ISO + Flash = Winner"
In response to Reply # 0


RO
          

Not bad at all, but in my book if one uses flash one should be allowed to go as low-iso as possible so 1600 seems a little too much. I would have preferred that the flash lighten up the scene enough for ISO 100-400.

Am I wrong?

Visit my Nikonians gallery.

  

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rasworth Basic MemberTue 14-Dec-10 08:55 PM
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#2. "RE: D7000 + Auto ISO + Flash = Winner"
In response to Reply # 1


Austin, US
          

Good question - remember I was shooting at f8 into a large room, bouncing off of the ceiling. I went back and re-shot at increasing fixed ISOs; at ISO 800 the SB600 barely generated enough light for proper exposure, so the D7000 algorithm is conservative in that it doesn't wring as much power out of the flash as possible, by a factor of two or so. And ISO 800 at 1/60 burned out the window light more than ISO 1600 at 1/160.

If I were doing it from scratch I would set the ss up to (probably) 1/250 in order to minimize the window light, and run the ISO up until the flash provided enough power, which would have been at 800. The "beauty" of the built-in auto iso smarts is its convenience/quickness; doesn't result in the optimum but does give a reasonable result.

So after writing the above I went back and set in manual mode f8 and 1/250 - I had to set ISO at 1000, not 800, in order not to run out of flash power (blinking lightning symbol). I had not taken into account the contribution from the ambient lighting at 1/60 as compared to 1/250. Again, the D7000 didn't get the absolutely best result on its own, but it wasn't far off.

Richard Southworth

  

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rasworth Basic MemberTue 14-Dec-10 09:44 PM
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#3. "RE: D7000 + Auto ISO + Flash = Winner"
In response to Reply # 2
Tue 14-Dec-10 09:45 PM by rasworth

Austin, US
          

And before somebody asks I also tried flash and Auto ISO in manual mode, at f8 and 1/250. Shot the same scene, the ISO popped up to 2500. This left me scratching my head, but I believe I have somewhat doped out what's going on.

The camera algorithms are set to achieve a balancing act between ambient light and flash. I had frozen the aperture and shutter speed, therefore the only way the camera could increase the ambient contribution was to up the ISO and lower flash power, which it did. As a human I was more concerned with minimizing burn-out at the windows; apparently the camera takes a more balanced approach, and strives to achieve some other mix taking into account the entire scene.

Clever little beast.

Richard Southworth

  

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