Originally posted by Russell-Evans No, the FOV being quoted for the fisheye on the Pentax site is the whole image circle FOV. The FOV being quoted the normal lenses is the HFOV. They are completely different measurements and to use them in a comparison is an error.

The ideal calculated values are the maximum. As you are quoting the fisheye as being over the calculated ideal, it is inaccurate from the start. There is no way to spin this, compare the same FOV measurements, simple.

Thank you

Russell

Actually, if you look at the numbers you posted, they confirm the ones posted by others. AFAIK, all FOV numbers for lenses are given as the diagonal.

audiobomber stated:

16-45mm:

**83º**-35º

you stated:

For normal lens at 16mm

VFOV

72.82 deg

HFOV

51.69 deg

FOV min. image circle

**82.84 deg**
They may have rounded, but that's practically the same number.

Originally posted by Russell-Evans This isn't correct as your using the marketing numbers on the 10-17mm and why I posted the ideal lens calculated values, i.e. best case numbers.

If we want to split hairs, technically, your numbers can also be called incorrect. At least, with respect to Pentax sensors sizes.

You apparently used the Nikon D1/DX as the basis. It has a sensor size of 23.6 x 15.5mm.

I believe the sensor size for Pentax cameras are:

K20d/k-7 =23.4 x 15.6 mm

all other Pentax=23.5 x 15.7mm

One thing the Pano Calculator reveals though, is some inaccuracy of specified angle of view for lenses on different sized sensors. Sigma states the angle of view of the 10-20mm is "102.4 - 63.8 degrees". But this is only true on a Sigma DSLR sensor (20.7x13.8mm). On the k20d/k-7 this range becomes 109.16 - 70.21 degrees.

This then accounts for my own error when I said the Sigma 10-20 is just over 100 degrees at 10mm.

Originally posted by Russell-Evans This isn't correct as your using the marketing numbers on the 10-17mm and why I posted the ideal lens calculated values, i.e. best case numbers.

I'm no expert on this, but since the numbers lined up, I'm guessing "FOV min image circle" is the diameter of the circle produced by the lens as it falls upon the sensor. This number, as you saw above, corresponds with the angle of view typically given for lenses. This angle of view is a diagonal one.