Steve'sDigicams

airbrushjohn · Jan 14, 2009, 7:36 PM

hi johng, i must not be paying attention and i do feel kinda silly asking this. but here is a example of a photo not a good one, but an example with the exif its 1/3200 @ f2.8 iso400 it says exposure bias +0.33 i really don't understand, how i did this except move the wheel on the back but how can that happen if i'm in aperture mode? please don't think i'm nuts, i just can't figure this out.

jschoenr · Jan 14, 2009, 7:45 PM

I'll take a stab.. If your exposure bias is +.33, then you are telling the camera you want the picture to be 1/3 overexposed. So, with ISO400, f/2.8 and no exposure bias (I think my camera calls it exposure compensation), the camera would've exposed it at 1/2500.. So, when you move the wheel on the camera, what you are telling it is - to adjust the exposure either + or - from what it meters. In Av mode, this means the shutter speed will either be faster or slower than whatever the cameras meters would normally do..

Jason

JohnG · Jan 14, 2009, 8:04 PM

Jason is dead on. The camera metered the shot at 1/4000 - your +1/3 EC changed the shutter speed to 1/3200.

Again in AV mode the back wheel applies exposure compensation. Positive EC forces the camera to use a slower shutter speed, negative EC forces the camera to use a faster shutter speed.

In TV mode that same wheel applies exposure compensation by adjusting the aperture up or down from the value the camera chooses for what it thinks is aproper exposure.

airbrushjohn · Jan 15, 2009, 9:16 PM

ok now i understand, so is this what you were doing to get the exposure in your shots? or is it, you are setting your exposure and iso and aperture in manual mode?
i really think i misunderstood what you were saying in your original post!! and thank you for taking the time to help me! john

JohnG · Jan 16, 2009, 5:00 AM

I shoot with manual exposure. And what I was saying is I generally treat ISO 6400 as if it were only 2/3 stops above 3200. So if I had camera set at 3200, f2.8 and 1/250. If I set ISO to 6400, instead of setting shutter to 1/500 I'll set it to 1/400 (2/3 stop above 1/250).

airbrushjohn · Jan 16, 2009, 8:00 PM

again, thank you for taking time to explain, i truly appreciate your time! john

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Jan 14, 2009, 7:36 PM	#11
airbrushjohn Senior Member Join Date: Feb 2007 Posts: 747	hi johng, i must not be paying attention and i do feel kinda silly asking this. but here is a example of a photo not a good one, but an example with the exif its 1/3200 @ f2.8 iso400 it says exposure bias +0.33 i really don't understand, how i did this except move the wheel on the back but how can that happen if i'm in aperture mode? please don't think i'm nuts, i just can't figure this out.

Jan 14, 2009, 7:45 PM	#12
jschoenr Senior Member Join Date: Aug 2007 Location: Apex, NC Posts: 218	I'll take a stab.. If your exposure bias is +.33, then you are telling the camera you want the picture to be 1/3 overexposed. So, with ISO400, f/2.8 and no exposure bias (I think my camera calls it exposure compensation), the camera would've exposed it at 1/2500.. So, when you move the wheel on the camera, what you are telling it is - to adjust the exposure either + or - from what it meters. In Av mode, this means the shutter speed will either be faster or slower than whatever the cameras meters would normally do.. Jason

Jan 14, 2009, 8:04 PM	#13
JohnG Moderator Join Date: Aug 2004 Posts: 8,529	Jason is dead on. The camera metered the shot at 1/4000 - your +1/3 EC changed the shutter speed to 1/3200. Again in AV mode the back wheel applies exposure compensation. Positive EC forces the camera to use a slower shutter speed, negative EC forces the camera to use a faster shutter speed. In TV mode that same wheel applies exposure compensation by adjusting the aperture up or down from the value the camera chooses for what it thinks is aproper exposure.

Jan 15, 2009, 9:16 PM	#14
airbrushjohn Senior Member Join Date: Feb 2007 Posts: 747	ok now i understand, so is this what you were doing to get the exposure in your shots? or is it, you are setting your exposure and iso and aperture in manual mode? i really think i misunderstood what you were saying in your original post!! and thank you for taking the time to help me! john

Jan 16, 2009, 5:00 AM	#15
JohnG Moderator Join Date: Aug 2004 Posts: 8,529	I shoot with manual exposure. And what I was saying is I generally treat ISO 6400 as if it were only 2/3 stops above 3200. So if I had camera set at 3200, f2.8 and 1/250. If I set ISO to 6400, instead of setting shutter to 1/500 I'll set it to 1/400 (2/3 stop above 1/250).

Jan 16, 2009, 8:00 PM	#16
airbrushjohn Senior Member Join Date: Feb 2007 Posts: 747	again, thank you for taking time to explain, i truly appreciate your time! john