some more Nikon print functions changed

to translate value 0 to n/a

src/nikonmn_int.cpp

@@ -3263,6 +3263,10 @@ std::ostream& Nikon3MakerNote::printFocusDistance(std::ostream& os, const Value&
     os.flags(f);
     return os;
   }
+  auto temp = value.toInt64();
+  if (temp == 0)
+    return os << _("n/a");
+
   double dist = 0.01 * pow(10.0, value.toInt64() / 40.0);
   std::ostringstream oss;
   oss.copyfmt(os);
@@ -3279,6 +3283,10 @@ std::ostream& Nikon3MakerNote::printAperture(std::ostream& os, const Value& valu
     os.flags(f);
     return os;
   }
+  auto temp = value.toInt64();
+  if (temp == 0)
+    return os << _("n/a");
+
   double aperture = pow(2.0, value.toInt64() / 24.0);
   std::ostringstream oss;
   oss.copyfmt(os);
@@ -3292,6 +3300,10 @@ std::ostream& Nikon3MakerNote::printFocal(std::ostream& os, const Value& value,
   if (value.count() != 1 || value.typeId() != unsignedByte) {
     return os << "(" << value << ")";
   }
+  auto temp = value.toInt64();
+  if (temp == 0)
+    return os << _("n/a");
+
   double focal = 5.0 * pow(2.0, value.toInt64() / 24.0);
   std::ostringstream oss;
   oss.copyfmt(os);
@@ -3959,6 +3971,10 @@ std::ostream& Nikon3MakerNote::printFocalLd4(std::ostream& os, const Value& valu
   if (value.count() != 1 || value.typeId() != unsignedShort) {
     return os << "(" << value << ")";
   }
+  auto temp = value.toInt64();
+  if (temp == 0)
+    return os << _("n/a");
+
   std::ostringstream oss;
   oss.copyfmt(os);
   os << std::fixed << std::setprecision(1) << value.toInt64() << " mm";
@@ -3970,6 +3986,10 @@ std::ostream& Nikon3MakerNote::printFocusDistanceLd4(std::ostream& os, const Val
   if (value.count() != 1 || value.typeId() != unsignedShort) {
     return os << "(" << value << ")";
   }
+  auto temp = value.toInt64();
+  if (temp == 0)
+    return os << _("n/a");
+
   double dist = 0.01 * pow(10.0, (value.toInt64() / 256.0) / 40.0);
   std::ostringstream oss;
   oss.copyfmt(os);

test/data/test_reference_files/CH0_0174.exv.out

@@ -115,8 +115,8 @@ Exif.NikonLd4.EffectiveMaxAperture           Byte        1  36  F2.8
 Exif.NikonLd4.LensID                         Short       1  0  0
 Exif.NikonLd4.MaxAperture                    Short       1  0  n/a
 Exif.NikonLd4.FNumber                        Short       1  0  n/a
-Exif.NikonLd4.FocalLength2                   Short       1  0  0 mm
+Exif.NikonLd4.FocalLength2                   Short       1  0  n/a
-Exif.NikonLd4.FocusDistance2                 Short       1  0  0.01 m
+Exif.NikonLd4.FocusDistance2                 Short       1  0  n/a
 Exif.Nikon3.RawImageCenter                   Short       2  2274 1515  2274 1515
 Exif.Nikon3.RetouchHistory                   Short      10  0 0 0 0 0 0 0 0 0 0  None
 Exif.Nikon3.ShutterCount                     Long        1  174  174