Getting unexpected result from easyaccess call ExifData::const_iterator apertureValue(const ExifData& ed)

[perdrix52]

I have a jpeg image that has the following metadata (from Windows properties)

F-stop: f5.6
Max Aperture: 4.96875

but this code:

if (iterator = apertureValue(exifData); exifData.end() != iterator)
{
	BitmapInfo.m_fAperture = iterator->toFloat();
	result = true;
}

returns a value of 4.9708538055419922 (4970854, 1000000 is the rational value). the tag number is 37378 == Exif.Image.ApertureValue

If it had returned a tag 37381 == Exif.Image.MaxApertureValue I could almost understand the value, but this?

exifprint says:D:\exiv2-build\bin>exifprint "C:\Users\amonra\Pictures_MG_2260.jpg"
Exif.Image.Make 0x010f Ascii 6 Canon
Exif.Image.Model 0x0110 Ascii 14 Canon EOS 20D
Exif.Image.XResolution 0x011a Rational 1 300/1
Exif.Image.YResolution 0x011b Rational 1 300/1
Exif.Image.ResolutionUnit 0x0128 Short 1 2
Exif.Image.Software 0x0131 Ascii 41 Adobe Photoshop Camera Raw 9.2 (Windows)
Exif.Image.DateTime 0x0132 Ascii 20 2015:11:15 10:35:41
Exif.Image.Artist 0x013b Ascii 39 David C. Partridge; David C. Partridge
Exif.Image.Copyright 0x8298 Ascii 25 David C. Partridge, 2015
Exif.Image.ExifTag 0x8769 Long 1 298
Exif.Photo.ExposureTime 0x829a Rational 1 1/640
Exif.Photo.FNumber 0x829d Rational 1 56/10
Exif.Photo.ExposureProgram 0x8822 Short 1 3
Exif.Photo.ISOSpeedRatings 0x8827 Short 1 400
Exif.Photo.ExifVersion 0x9000 Undefined 4 48 50 51 48
Exif.Photo.DateTimeOriginal 0x9003 Ascii 20 2014:07:31 12:25:01
Exif.Photo.DateTimeDigitized 0x9004 Ascii 20 2014:07:31 12:25:01
Exif.Photo.ShutterSpeedValue 0x9201 SRational 1 9321928/1000000
Exif.Photo.ApertureValue 0x9202 Rational 1 4970854/1000000
Exif.Photo.ExposureBiasValue 0x9204 SRational 1 0/2
Exif.Photo.MaxApertureValue 0x9205 Rational 1 496875/100000
Exif.Photo.MeteringMode 0x9207 Short 1 1
Exif.Photo.Flash 0x9209 Short 1 16
Exif.Photo.FocalLength 0x920a Rational 1 115/1
Exif.Photo.FocalPlaneXResolution 0xa20e Rational 1 3504000/885
Exif.Photo.FocalPlaneYResolution 0xa20f Rational 1 2336000/590
Exif.Photo.FocalPlaneResolutionUnit 0xa210 Short 1 2
Exif.Photo.CustomRendered 0xa401 Short 1 0
Exif.Photo.ExposureMode 0xa402 Short 1 0
Exif.Photo.WhiteBalance 0xa403 Short 1 0
Exif.Photo.SceneCaptureType 0xa406 Short 1 0
Exif.Photo.CameraOwnerName 0xa430 Ascii 19 David C. Partridge
Exif.Photo.BodySerialNumber 0xa431 Ascii 11 1350200219
Exif.Photo.LensSpecification 0xa432 Rational 4 18/1 200/1 0/0 0/0
Exif.Photo.LensModel 0xa434 Ascii 14 18.0-200.0 mm
Exif.Thumbnail.Compression 0x0103 Short 1 6
Exif.Thumbnail.XResolution 0x011a Rational 1 72/1
Exif.Thumbnail.YResolution 0x011b Rational 1 72/1
Exif.Thumbnail.ResolutionUnit 0x0128 Short 1 2
Exif.Thumbnail.JPEGInterchangeFormat 0x0201 Long 1 888
Exif.Thumbnail.JPEGInterchangeFormatLength 0x0202 Long 1 15316

So at least the library is returning the value in the Exif.Photo.ApertureValue tag!!! Looks like the Camara or PS or Lightroom messed up

[perdrix52]

if (iterator = fNumber(exifData); exifData.end() != iterator)
{
	BitmapInfo.m_fAperture = iterator->toFloat();
	result = true;
}

does return the expected value ...

[perdrix52]

Not library fault - data is just odd!