View Full Version : Feild of view

17-Nov-2007, 15:20
Ive read that the FOV on a 6x17 with a 90mm lens is about a 24mm on a 35mm so is this the same with a 5x7 or 4x5 camera as well

Paul Ewins
17-Nov-2007, 15:53
When I think of FOV in LF and pano cameras I am thinking of horizontal FOV rather than the diagonal FOV that is usually used to express the FOV of a 35mm lens. It is much more usual in LF to use the wide angle lenses to fit in something wide (e.g. landscape) or something tall (buildings, mountains) than something that is both wide and tall. In 35mm wide angles are often used for street shooting where you want to get more of the whole scene, so diagonal FOV makes sense. Using horizontal FOV also ignores the fact that different formats have different Height to Width ratios.

Using this approach:
a 24mm lens on a 35mm camera has a horizontal FOV of 73.7 degrees (diagonal 84.1);
a 90mm lens on 6x17 is 86.7 degrees (89.9) assuming neg is actually 170mm long;
a 90mm lens on 4x5 is 69.6 degrees (83.3);
a 90mm lens on 5x7 is 88.4 degrees (96.5).

The nearest match for a 24mm on the 6x17 format would be around 110 - 115mm (Super-Symmar or Grandagon). A 90mm on 6x17 (or 5x7) is actually closer to a 19mm lens.

Rob Champagne
17-Nov-2007, 17:41
convert your 6x17cm into inches and then it should become more obvious for you.
it becomes approx 2.25x6.5 so horizonatlly a 5x7 camera has a tad wider angle of view than your 6x17 and a 4x5 has significantly less horizontal FOV than your 6x17.

but as has been said, with large format people think in terms of angle of coverage that a lens has and how much room for shifts that allows. not the same thing as angle of view which is used for non technical cameras.

steve simmons
17-Nov-2007, 17:52
The terms are generally

angle of coverage and angle of view

Angle of coverage is determined by the design of the lens and does not depend on the size of the film area. Angle of coverage is what determines the image circle of the lens.

Angle of view depends on the film size and varies even with the same lens as you change film formats.

steve simmons

Bruce Watson
18-Nov-2007, 08:17
Angle of view (http://en.wikipedia.org/wiki/Angle_of_view) definition. Do a little math and it will make some level of sense to you maybe.