D5100: Underexposure using flash

J

jim.londos

New member
Hi folks,

​I am not too sure if I can put it down correctly, but I will try:

My D5100 + AF-S 35mm/1.8, when in P mode and with the flash activated, indoors with moderate light, uses a strange mix of settings (Auto ISO, 3200 maximum and minimum speed at 1/125 selected in the menu settings).
Results: an aperture around f6.3-f7.1, a speed of 1/125 and ISO 3200, all this leading to underexposure, indicated by the camera itself, before shooting.

The strange things are:
1. The lens can perform brighter than that (up to f1.8), still the camera chooses a smaller aperture (f6.3-7.1) and with the above settings, the image is underexposed.
2. I tested other Nikon cameras (e.g. D5200, D3000, even another D5100 body) and they show the same behavior.
3. I tested the Nikon D90 and it DOESN'T show this behaviour. Meaning, that it will choose a wider aperture setting, so that the picture doesn't get underexposed AND the sensitivity drops to more reasonable ISO values.
4. I brought my D5100 to Nikon, where the testing machine found the camera within Nikon's specs.

So, any smart ideas why this is happening? Is this a bug or a feature?
 
D

Dave_W

The Dude
When you tell the camera that you're going to use a flash, it prepares for the moment of flash and expects there to be more light at that moment than when you're looking through it w/o the flash. Given this, the read-out on the lens will appear to be "underexposed" but the exposure is set for the moment of the flash and not for anytime the flash is not occurring.
 
J

jim.londos

New member
Horoscope Fish said:
What flash unit are you using and have you tried a setting other than "P"rogram?
Click to expand...

Regarding flash, I am using the built-in one.
Regarding other programs, on either A or S, this doesn't happen. In both cases, the parameters used by D5100 are the same with or without flash: f1.8 - 1/125 - ISO 1250. In P I am getting f1.8 - 1/125 - ISO 1250 without flash and f7.1 - 1/125 - ISO 3200 - underexposure with flash.
 
J

jim.londos

New member
Dave_W said:
When you tell the camera that you're going to use a flash, it prepares for the moment of flash and expects there to be more light at that moment than when you're looking through it w/o the flash. Given this, the read-out on the lens will appear to be "underexposed" but the exposure is set for the moment of the flash and not for anytime the flash is not occurring.
Click to expand...

Hi Dave,

what you say makes sense, of course. The picture, when taken, doesn't seem to be underexposed at the end. Rightly put.

Still, the question remains:
1. Why doesn't this happen using A or S ? As mentioned above, in both cases, the parameters used by D5100 are the same with or without flash: f/1.8 - 1/125 - ISO 1250. In P I am getting f/1.8 - 1/125 - ISO 1250 without flash and f/7.1 - 1/125 - ISO 3200 - underexposure indication with flash.
2. What kind of logic lies behind narrowing the aperture and increasing the sensitivity, leading to more noise, while other models (e.g. D90) keep the aperture wide and the sensitivity low? I mean, low noise and wide aperture is one of the reasons of using a fast lens after all, right?
 
D

Don Kuykendall_RIP

RIP :(
First off why do you have the ISO set so high to begin with? Try setting the ISO to :
ISO sensitivity 200
Auto ISO ON
Maximum sensitivity 400
Minimum shutter speed 1/60

If you are using flash you should never need ISO at 1250 much less 3200.

Try it again set like this and see what you get. Also post one of the pictures here so we can see what you are doing.
 
J

jim.londos

New member
pedroj said:
Post some pics with the exif data...You don't have the strength of the flash wound down do you....
Click to expand...

Hi Pedro.

Thanks for the comment. I don't think that I touched the flash settings. No flash compensation set in the camera.

I have uploaded some test pictures below. In all three modes: P, A (set at f/1.8), S (set at 1/125), with and without flash, whereas the ISO settings are: 100 / Auto on / ISO limit 3200 / speed limit 1/125.

 A - no flash - DSC_0384.jpg
Filename - A - no flash - DSC_0384.JPGMake - NIKON CORPORATION
Model - NIKON D5100

ExposureTime - 1/125 seconds
FNumber - 1.80
ExposureProgram - Aperture priority
ISOSpeedRatings - 1400

MaxApertureValue - F 1.74
MeteringMode - Center weighted average
LightSource - Auto
Flash - Not fired
FocalLength - 35.00 mm

ExposureMode - Auto
White Balance - Auto

FocalLengthIn35mmFilm - 52 mm

ISO Setting - 1400
Image Quality - BASIC
White Balance - AUTO
Focus Mode - AF-A
Flash Setting - NORMAL

ISO 2 - 100

Flash Used - Not fired
Bracketing - 2162688
Noise Reduction - OFF



A - with flash - DSC_0385.jpg
Filename - A - with flash - DSC_0385.JPGMake - NIKON CORPORATION
Model - NIKON D5100

ExposureTime - 1/125 seconds
FNumber - 1.80
ExposureProgram - Aperture priority
ISOSpeedRatings - 640

MaxApertureValue - F 1.74
MeteringMode - Center weighted average
LightSource - Auto
Flash - Flash fired, compulsory flash mode
FocalLength - 35.00 mm

FocalLengthIn35mmFilm - 52 mm
SceneCaptureType - Standard
GainControl - Low gain up

ISO Setting - 640
Image Quality - BASIC
White Balance - AUTO
Focus Mode - AF-A
Flash Setting - NORMAL
Flash Mode - Built-in,TTL-BL
White Balance Adjustment - 0
White Balance RB - 742
Exposure Adjustment - 68608
Thumbnail IFD offset - 11422
Flash Compensation - 67072
Lens type - AF-D G
Lens - 1514
Flash Used - On camera
Bracketing - 2162688
Noise Reduction - OFF
Total pictures - 10567



P - no flash - DSC_0382.jpg
Filename - P - no flash - DSC_0382.JPGMake - NIKON CORPORATION
Model - NIKON D5100
Orientation - Top left
XResolution - 300
YResolution - 300
ResolutionUnit - Inch
Software - Ver.1.01
DateTime - 2013:04:17 17:09:08
YCbCrPositioning - Co-Sited
ExifOffset - 228
ExposureTime - 1/125 seconds
FNumber - 1.80
ExposureProgram - Normal program
ISOSpeedRatings - 1400
ExifVersion - 0230
DateTimeOriginal - 2013:04:17 17:09:08
DateTimeDigitized - 2013:04:17 17:09:08
ComponentsConfiguration - YCbCr
CompressedBitsPerPixel - 1 (bits/pixel)
ExposureBiasValue - 0.00
MaxApertureValue - F 1.74
MeteringMode - Center weighted average
LightSource - Auto
Flash - Not fired
FocalLength - 35.00 mm
UserComment -
SubsecTime - 60
SubsecTimeOriginal - 60
SubsecTimeDigitized - 60
FlashPixVersion - 0100
ColorSpace - sRGB
ExifImageWidth - 2464
ExifImageHeight - 1632
InteroperabilityOffset - 37112
SensingMethod - One-chip color area sensor
FileSource - Other
SceneType - Other
CustomRendered - Normal process
ExposureMode - Auto
White Balance - Auto
DigitalZoomRatio - 1 x
FocalLengthIn35mmFilm - 52 mm
SceneCaptureType - Standard
GainControl - High gain up
Contrast - Normal
Saturation - Normal
Sharpness - Normal
SubjectDistanceRange - Unknown


GPS information: -
GPSVersionID - 2.3.0.0


Maker Note (Vendor): -
Data version - 0210 (808595760)
ISO Setting - 1400
Image Quality - BASIC
White Balance - AUTO
Focus Mode - AF-A
Flash Setting - NORMAL
Flash Mode -
White Balance Adjustment - 0
White Balance RB - 742
Exposure Adjustment - 68608
Thumbnail IFD offset - 11422
Flash Compensation - 67072
ISO 2 - 100
Lens type - AF-D G
Lens - 1514
Flash Used - Not fired
Bracketing - 2162688
Noise Reduction - OFF
Total pictures - 10564


Thumbnail: -
Compression - 6 (JPG)
XResolution - 300
YResolution - 300
ResolutionUnit - Inch
JpegIFOffset - 37272
JpegIFByteCount - 8536
YCbCrPositioning - Co-Sited


P - with flash - DSC_0383.jpg
Filename - P - no flash - DSC_0382.JPGMake - NIKON CORPORATION
Model - NIKON D5100
Orientation - Top left
XResolution - 300
YResolution - 300
ResolutionUnit - Inch
Software - Ver.1.01
DateTime - 2013:04:17 17:09:08
YCbCrPositioning - Co-Sited
ExifOffset - 228
ExposureTime - 1/125 seconds
FNumber - 1.80
ExposureProgram - Normal program
ISOSpeedRatings - 1400
ExifVersion - 0230
DateTimeOriginal - 2013:04:17 17:09:08
DateTimeDigitized - 2013:04:17 17:09:08
ComponentsConfiguration - YCbCr
CompressedBitsPerPixel - 1 (bits/pixel)
ExposureBiasValue - 0.00
MaxApertureValue - F 1.74
MeteringMode - Center weighted average
LightSource - Auto
Flash - Not fired
FocalLength - 35.00 mm
UserComment -
SubsecTime - 60
SubsecTimeOriginal - 60
SubsecTimeDigitized - 60
FlashPixVersion - 0100
ColorSpace - sRGB
ExifImageWidth - 2464
ExifImageHeight - 1632
InteroperabilityOffset - 37112
SensingMethod - One-chip color area sensor
FileSource - Other
SceneType - Other
CustomRendered - Normal process
ExposureMode - Auto
White Balance - Auto
DigitalZoomRatio - 1 x
FocalLengthIn35mmFilm - 52 mm
SceneCaptureType - Standard
GainControl - High gain up
Contrast - Normal
Saturation - Normal
Sharpness - Normal
SubjectDistanceRange - Unknown


GPS information: -
GPSVersionID - 2.3.0.0


Maker Note (Vendor): -
Data version - 0210 (808595760)
ISO Setting - 1400
Image Quality - BASIC
White Balance - AUTO
Focus Mode - AF-A
Flash Setting - NORMAL
Flash Mode -
White Balance Adjustment - 0
White Balance RB - 742
Exposure Adjustment - 68608
Thumbnail IFD offset - 11422
Flash Compensation - 67072
ISO 2 - 100
Lens type - AF-D G
Lens - 1514
Flash Used - Not fired
Bracketing - 2162688
Noise Reduction - OFF
Total pictures - 10564


Thumbnail: -
Compression - 6 (JPG)
XResolution - 300
YResolution - 300
ResolutionUnit - Inch
JpegIFOffset - 37272
JpegIFByteCount - 8536
YCbCrPositioning - Co-Sited


S - no flash - DSC_0386.jpg
Filename - S - no flash - DSC_0386.JPGMake - NIKON CORPORATION
Model - NIKON D5100
Orientation - Top left
XResolution - 300
YResolution - 300
ResolutionUnit - Inch
Software - Ver.1.01
DateTime - 2013:04:17 17:10:53
YCbCrPositioning - Co-Sited
ExifOffset - 228
ExposureTime - 1/125 seconds
FNumber - 1.80
ExposureProgram - Shutter priority
ISOSpeedRatings - 1400
ExifVersion - 0230
DateTimeOriginal - 2013:04:17 17:10:53
DateTimeDigitized - 2013:04:17 17:10:53
ComponentsConfiguration - YCbCr
CompressedBitsPerPixel - 1 (bits/pixel)
ExposureBiasValue - 0.00
MaxApertureValue - F 1.74
MeteringMode - Center weighted average
LightSource - Auto
Flash - Not fired
FocalLength - 35.00 mm
UserComment -
SubsecTime - 50
SubsecTimeOriginal - 50
SubsecTimeDigitized - 50
FlashPixVersion - 0100
ColorSpace - sRGB
ExifImageWidth - 2464
ExifImageHeight - 1632
InteroperabilityOffset - 36962
SensingMethod - One-chip color area sensor
FileSource - Other
SceneType - Other
CustomRendered - Normal process
ExposureMode - Auto
White Balance - Auto
DigitalZoomRatio - 1 x
FocalLengthIn35mmFilm - 52 mm
SceneCaptureType - Standard
GainControl - High gain up
Contrast - Normal
Saturation - Normal
Sharpness - Normal
SubjectDistanceRange - Unknown


GPS information: -
GPSVersionID - 2.3.0.0


Maker Note (Vendor): -
Data version - 0210 (808595760)
ISO Setting - 1400
Image Quality - BASIC
White Balance - AUTO
Focus Mode - AF-A
Flash Setting - NORMAL
Flash Mode -
White Balance Adjustment - 0
White Balance RB - 742
Exposure Adjustment - 68608
Thumbnail IFD offset - 11422
Flash Compensation - 67072
ISO 2 - 100
Lens type - AF-D G
Lens - 1514
Flash Used - Not fired
Bracketing - 2162688
Noise Reduction - OFF
Total pictures - 10568


Thumbnail: -
Compression - 6 (JPG)
XResolution - 300
YResolution - 300
ResolutionUnit - Inch
JpegIFOffset - 37120
JpegIFByteCount - 8602
YCbCrPositioning - Co-Sited


S - with flash - DSC_0387.jpg
Filename - S - with flash - DSC_0387.JPGMake - NIKON CORPORATION
Model - NIKON D5100
Orientation - Top left
XResolution - 300
YResolution - 300
ResolutionUnit - Inch
Software - Ver.1.01
DateTime - 2013:04:17 17:11:04
YCbCrPositioning - Co-Sited
ExifOffset - 228
ExposureTime - 1/125 seconds
FNumber - 1.80
ExposureProgram - Shutter priority
ISOSpeedRatings - 720
ExifVersion - 0230
DateTimeOriginal - 2013:04:17 17:11:04
DateTimeDigitized - 2013:04:17 17:11:04
ComponentsConfiguration - YCbCr
CompressedBitsPerPixel - 1 (bits/pixel)
ExposureBiasValue - 0.00
MaxApertureValue - F 1.74
MeteringMode - Center weighted average
LightSource - Auto
Flash - Flash fired, compulsory flash mode
FocalLength - 35.00 mm
UserComment -
SubsecTime - 20
SubsecTimeOriginal - 20
SubsecTimeDigitized - 20
FlashPixVersion - 0100
ColorSpace - sRGB
ExifImageWidth - 2464
ExifImageHeight - 1632
InteroperabilityOffset - 38286
SensingMethod - One-chip color area sensor
FileSource - Other
SceneType - Other
CustomRendered - Normal process
ExposureMode - Auto
White Balance - Auto
DigitalZoomRatio - 1 x
FocalLengthIn35mmFilm - 52 mm
SceneCaptureType - Standard
GainControl - Low gain up
Contrast - Normal
Saturation - Normal
Sharpness - Normal
SubjectDistanceRange - Unknown


GPS information: -
GPSVersionID - 2.3.0.0


Maker Note (Vendor): -
Data version - 0210 (808595760)
ISO Setting - 720
Image Quality - BASIC
White Balance - AUTO
Focus Mode - AF-A
Flash Setting - NORMAL
Flash Mode - Built-in,TTL-BL
White Balance Adjustment - 0
White Balance RB - 742
Exposure Adjustment - 68608
Thumbnail IFD offset - 11422
Flash Compensation - 67072
ISO 2 - 100
Lens type - AF-D G
Lens - 1514
Flash Used - On camera
Bracketing - 2162688
Noise Reduction - OFF
Total pictures - 10569


Thumbnail: -
Compression - 6 (JPG)
XResolution - 300
YResolution - 300
ResolutionUnit - Inch
JpegIFOffset - 38444
JpegIFByteCount - 8761
YCbCrPositioning - Co-Sited

As you can see, in both A and S, the D5100 doesn't alter neither speed nor aperture when activating the flash. It just reduces the sensitivity from 1400 to 640-720. In P it narrows the aperture to f/7.1 and increases the sensitivity to 3200.

Do you think this makes sense?

 
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