Hi.

I've just discovered that Lightromm 3.4 and earlier wrongly displays SubjectDistance EXIF tag if camera focus distance was set to infinity.

According to EXIF specification SubjectDistance tag is stored using two numbers - numerator and denominator.

And if numerator is zero - subject distance should be reported as unknown and if it is set to 0xFFFFFFFF - subject distance is infinity.

Quote from EXIF 2.2 specification:

SubjectDistance:

The distance to the subject, given in meters. Note that if the numerator of the recorded value is FFFFFFFF.H,

Infinity shall be indicated; and if the numerator is 0, Distance unknown shall be indicated.

But instead of displaying infinity - lightroom shows numeric value.

For example, in my photo I have numerator equal to 0xFFFFFFFF and denominator equal to 1000.

Lightroom reports distance of 4.29 Mm (million of meters 0xFFFFFFFF/1000 = 4294967295/1000 = 4.29*10^6), which is numerically right, but should be reported as infinity.

At the moment, Lightroom shows infinity ONLY if the numerator is 0xFFFFFFFF AND denominator is 1, which is wrong.

According to EXIF specification, if the numerator is 0xFFFFFFFF - denominator does not matter at all.

I've just discovered that Lightromm 3.4 and earlier wrongly displays SubjectDistance EXIF tag if camera focus distance was set to infinity.

According to EXIF specification SubjectDistance tag is stored using two numbers - numerator and denominator.

And if numerator is zero - subject distance should be reported as unknown and if it is set to 0xFFFFFFFF - subject distance is infinity.

Quote from EXIF 2.2 specification:

SubjectDistance:

The distance to the subject, given in meters. Note that if the numerator of the recorded value is FFFFFFFF.H,

Infinity shall be indicated; and if the numerator is 0, Distance unknown shall be indicated.

But instead of displaying infinity - lightroom shows numeric value.

For example, in my photo I have numerator equal to 0xFFFFFFFF and denominator equal to 1000.

Lightroom reports distance of 4.29 Mm (million of meters 0xFFFFFFFF/1000 = 4294967295/1000 = 4.29*10^6), which is numerically right, but should be reported as infinity.

At the moment, Lightroom shows infinity ONLY if the numerator is 0xFFFFFFFF AND denominator is 1, which is wrong.

According to EXIF specification, if the numerator is 0xFFFFFFFF - denominator does not matter at all.

Jim Wilde

Mark Sirota