Puzzled by ISO performance

Joined
May 4, 2007
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I tried out my newly purchased 24-70 yesterday in a room where are retirement party was being thrown. The room was lit by recessed lighting and had a window that spanned the entire width of the room with vertical blinds pretty much closed. Even though the blinds were closed, the 2:00 sun was enough to light the room fairly well for people to see but would have been considered dim for a camera I would imagine.

I was playing around with the ISO and cranked it up to 2500 to see what the results would be. I was surprised that at f/2.8 in Aperture Priority I was getting shutter speeds as slow as 1/50. I would have thought that it would have been quite a bit faster or am I missing something?
 
Joined
Jan 15, 2008
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Hi,
the way you describe the lighting I think your results are as expected. The shutter, aperture and ISO combination give lighting value of LV 4. This falls in the category of approximately "typical candle light" and just below "typical indoor lighting".

See the second table from the top:
http://www.earthboundlight.com/phototips/exposure-stops-here.html

If your camera was pointing at a dark suit or similar at the time you checked the shutter speed, that would have given you a stop or even two slower shutter speed, than a gray suit or dress.
 
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Joined
Mar 10, 2008
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Michigan
It sounds like you're shooting in aperture priority mode with auto ISO turned off. Seems like if you're limiting the ISO to 2500 and setting the aperture to 2.8, the camera's high ISO performance is not going to have anything to do with the shutter speed it expects to see for a specific EV.

I would've bumped up the ISO.
 
Joined
May 4, 2007
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It sounds like you're shooting in aperture priority mode with auto ISO turned off. Seems like if you're limiting the ISO to 2500 and setting the aperture to 2.8, the camera's high ISO performance is not going to have anything to do with the shutter speed it expects to see for a specific EV.

I would've bumped up the ISO.
Yeah I was thinking about that later and wondered what the ISO would have been if I had set it to Auto.
 
Joined
Mar 10, 2008
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Yeah I was thinking about that later and wondered what the ISO would have been if I had set it to Auto.
Most likely if you were sitting there with a D300 and locked it in at 2500 ISO, f2.8 the EV would've calculated 1/50 shutter speed as well. The difference would be the d300 and the noise coming through. If it came back with a shutter speed that was drastically different I'd be worried that one of them was having issues.
 
Joined
Feb 7, 2008
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Texas
I agree with the others, it sounds about right based by what you were saying. Aperture f/2.8 really isn't that wide when you're in low light. I usually use up to ISO 6400 on my D700, so don't be afraid to try it.

For example, I'm pretty certain this photo was around ISO 6400 (or maybe 5000, something pretty high)

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


Take advantage of the ridiculously low noise at high ISO...:smile:
 
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Nov 22, 2007
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San Diego
James, were you using matrix metering or spot? Also like the other said, dont be afraid of 3200/6400 :)
 
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James, were you using matrix metering or spot? Also like the other said, dont be afraid of 3200/6400 :)
I bounced around. Sometimes used matrix, sometimes center-weighted, sometimes spot. If I took a picture of someone near the window where they were severely backlit, I used spot. For other parts of the room I switched it up. I would have to look at the meta-data to get an accurate breakdown.
 
Joined
Jul 29, 2009
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Northern VA
I agree with others, I wouldnt be afraid to go above 2500, 3200 would have given you a little more speed and 6400 would have given you over 1/100th

adding a tungsten gelled flash and bouncing it off the ceiling would have helped add some light to the room as well.
 

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