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I own a D7200 and am still learning how to use all of its features. I just noticed the camera is consistently choosing high ISO (3200-6400) indoors under low light conditions even when the built-in flash is ON. I observed this behavior in both A and M modes with auto-iso. If the flash is OFF, camera would chose more or less that same ISO, but that is understandable. But I couldn't really understand why it is still using same ISO with flash.

When I set ISO manually to 100-200 with flash ON, I am getting very decent results with no noise. The default behavior of camera of choosing high ISO is generally producing similar overall looking images but with very high noise (because of the high ISO).

Is there a way to set camera properly to choose lower ISO when flash is ON?

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    What shutter speed does the camera choose when in A mode? What are you setting shutter speed to in M mode? And in either/both modes, what aperture are you choosing? – scottbb Sep 2 '16 at 22:28
  • @scottbb Shutter and Aperture adjustments don't seem to work. Camera seems to calculate same exposure settings for both flash ON and OFF. In M mode I normally used 1/60. A mode, camera also chose 1/60 as I enforced it through setting. – meharo Sep 3 '16 at 7:47
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Use a hot shoe flash.

The D7200 is one of the later models with the latest way that Nikon Auto ISO reacts with flash (there have been three methods on iTTL models).

If a hot shoe flash is used (a flash model recognized by the camera, meaning that can communicate with the camera), then Auto ISO will only advance at most 4x ISO (two stops) above Minimum ISO if using the hot shoe flash. However, the internal flash is exempt from this rule, and Auto ISO will seek whatever high level for the ambient, regardless of flash.

The solution for internal flash is the same for a manual flash... turn Auto ISO off.

  • Thank you for the info. I decided to use M mode and flash exposure compensation as necessary though it is not the optimum solution I hoped for. A mode doesn't seem to work as camera reduces the shutter speed a lot because I set ISO 100 manually. It doesn't seem to honor my 1/60 minimum setting. – meharo Sep 3 '16 at 7:38
  • Turning Auto ISO off is the easy and good way. Camera A mode sets exposure settings for the ambient, regardless if flash is present (including Auto ISO unless hot shoe flash). Then TTL flash adapts flash power level for whatever those settings are. Using camera M mode allows your control of the settings (TTL flash is still automatic in camera M mode). Exposure Compensation does not affect your camera M mode settings, but it will affect TTL flash. – WayneF Sep 3 '16 at 17:32
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The camera is behaving this way because the built in flash is relatively weak compared to most external flashes. Even if you are shooting at closer distances, where the built in flash does have enough power to use a lower ISO setting, the camera is apparently applying the same set of rules as if the distance to subject where longer.

When using an external flash the camera will apply a different set of rules with regard to AUto ISO than with the internal flash.

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Flash photography is tricky at first. In a nutshell, what you should be metering is the background of the subject which usually is underexposed by 1-2 stops. In this manner the flash will properly expose the subject for the calculated shutter speed while the camera exposes the background according to the camera's metering. You'll end up with a properly exposed subject and a slightly underexposed background. Read Neil's website and his wonderful book on this subject. It's a first rate book. If I had to read one book on flash photography, it's this one. http://neilvn.com/tangents/

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