15mm Fisheye vs 10-22 EF-s - which is wider?

[klfi]

Just wondering how the field of view of a defished 15mm fisheye

compares with that of a wide rectiliner lens, in particular, the new

10-22EF-S or sigma 12-24mm.

 

What is the effective FOV of the defished 15mm fisheye on a 1.6x

DSLR?

 

 

Thanks

Kev

[richard thompson www.fotoz]

I saw a thread on another forum where someone tested it out.

When defished and then cropped to the 3:2 format, it was approx equiv fov (field of view) of approx 20mm.

 

Correct me if anyone has tested this first hand, as this information is second hand.

 

Also consider the workflow. Do you really want to have to defish a lot of your wideangle shots ? Of course - the plus side is the f2.8 -its the brightest WA solution for a 1.6 cropper.

[bobatkins]

A 16mm fisheye gives about the same horizontal FOV as a 20mm lens on a full frame camera in the case of the EOS 10D. A 10mm lens would equate to a 16mm lens on a full frame camera.

 

Therefore I'm pretty sure the 10mm is the wider lens. A 12mm would be about the same as a 16mm fisheye (19.2mm vs 20mm), maybe slightly wider than a 15mm.

[tommyinca]

I did some test with a yard stick on my 16mm Zenitar fisheye/D300 Drebel. After defish, the picture show 4.21 feet of wall coverage when it is 3 feet back. This translate to 70.1 degree FOV or a 16.1mm lens equv (35mm lens). Without de-fish, the image has a 8.1% distortion and a horizontal FOV of 75.6 degree or a 14.7mm lens equv (35mm lens).

 

The up side on a fisheye is that you get to control the trade off between FOV and the amount of distortion.

 

Note: I hope my math are not too rusty.

[tommyinca]

Added Info.

 

With 1.6X sensor, the FOV translate to 25.8mm with 0% distortion and 23.5mm with 8% distortion. The FOV measurement are for the left and right edges at the center. The FOV at the corner for a fisheye is more before defish.

[richard thompson www.fotoz]

Fisheye: 4*arcsin(sensor size/(focal length*4))

Rectilinear: 2*arctan(sensor size/(focal length*2))

 

300D sensor size = 22.7 mm by 15.1 mm

 

Horizontal Field of view calculation.

 

15mm Fisheye on 300D = 88.92 degrees

10mm Rectilinear on 300D = 97.24 degrees

 

Fisheye isn't as wide even before de-fishing and cropping back to 3:2.

[bobatkins]

Tommy - I don't know how you made your measurements, but I think they are in error.

 

I see a 16mm fisheye on a 10D = a 20mm rectilinear on a full frame camera, based on horizontal FOV.

 

If you use Richard's formula, you'll see that a 16mm fisheye on a 10D should have an 83 degree HFOV, while a 20mm rectilinear on a full frame camera should have a 84 degree HFOV, which agrees well with my observations.

 

Defishing the image doesn't change the horizontal FOV - or the vertical FOV. You do change the digonal FOV though. You can see this in the image pair below (taken with EOS 10D and 16mm fisheye). Of course if you crop the defished image back to 3:2 you do lose horizontal FOV.<div></div>

[mike_morgan1]

Nice example Bob. You've been very helpful here.

[kjeld_olesen]

Horizontal and vertically, the 10, but diagonally the 15 fisheye (BEFORE defishing)

 

http://www.acapixus.dk/photography/angle_of_view.htm