90 Degree Lenses

[petrochemist]

I've no idea why you consider a 90° FOV special but for the sake of completeness here's a list of diagonal measurements for various digital sensor types used in interchangeable lens cameras:

Sensor diagonal/mm
1/2.3" 7.66 (Pentax Q)
1/1.7" 9.5 (Pentax Q7)
1" type 15.86 (Nikon CX)
MFT 21.6
Foveon X3 24.9 (Sigma SD14...)
Canon APSC 26.7
Other APSC 28.2 to 28.4
Canon APSH 33.5
'Full frame' 43.0 to 43.3
Typical MF 55 (Pentax 645D, Fuji GFX 50s...)
Large MF 67.4 (Phase One P65+)

135 film '35mm' is 43.27mm in it's standard still mode there are several other sizes also used for this film (at least 4 historically for cine)

If you want to work out the FOV for any sensor dimension (diagonal, horizontal etc) & any rectilinear focal length you can used the following formula (specified for Excel)
Angle=DEGREES(2*ATAN(Sensor dimension/(Focal length ^2)))
Without the 'degrees' excel will give the answer in radians - 90° is PI/2 (roughly 1.5707963) radians.

If we want to go to 180° that means we need to loose the rectilinear designs and go with a fish-eye of which there are multiple types each having a different focal length for a particular FOV at X displacement. The differences here can be dramatic at the focal length where an 'orthogonal' fisheye gives 180°, a stereographic type will have under 110° (Orthogonal designs can't go beyond 180°)

 

[NS: Nikon Shooter]

-

220° AoV is the largest I know of, a feature of the
6 mm fisheye by Nikkor.

Where does the value of 360° FoV come from???

 

[480sparky]

-

220° AoV is the largest I know of, a feature of the
6 mm fisheye by Nikkor.

Where does the value of 360° FoV come from???

Nikon, a few years back, ventured into the real of action cams with a dual-lens offering that did 360x180° video.

 

[NS: Nikon Shooter]

Nikon, a few years back, ventured into the real of action cams with a dual-lens offering that did 360x180° video.

That's pretty standard in terms of fisheye but the 6mm
was covering 360° vertical X 220° horizontal.

 

[480sparky]

That's pretty standard in terms of fisheye but the 6mm
was covering 360° X 220°.

Not with a single-lens.

 

[NS: Nikon Shooter]

Not with a single-lens.

Unless my memory fails me… I think so, absolutely.

 

[480sparky]

Unless my memory fails me… I think so, absolutely.

220, yes. 360.... I seriously doubt that.

Check out this rare Nikkor 17.3mm f/4 220° fisheye lens from Nikon listed on eBay for $150k - Nikon Rumors

A rare Nikkor 17.3mm f/4 220° fisheye lens from Nikon is currently listed for sale on eBay for $149,500. The lens can cover a medium format image circle. Additional information and pictures: This is rarer than the Holy Grail Nikon 6mm 2.8. So, I guess there is a “New” Holy Grail! Ok, this lens...

nikonrumors.com

 

[NS: Nikon Shooter]

Not with a single-lens.

For sure not!

!220, yes. 360.... I seriously doubt that.

We totally agree and talk about the same thing…
just from different geometric planes.

 

[VidThreeNorth]

What was special about a 90 degree lens? Photographically, nothing as far as I'm concerned, it is just another "ultra-wide". The problem was that about 5 - 6 years ago, "GitUp" was calling 3 different lenses with 3 different focal lengths all "90 degree" lenses, and I had to figure out which one was right. As it turned out, their 3.85mm lens was almost 90 degree when used for still pictures (full sensor), but even that one was not "90 degree" when used for 16 x 9 video, so my opinion was that none of them was actually a "90 degree" lens. The other focal lengths were roughly 4.1mm and 4.35mm. That's what I described in the other topic which I mentioned right at the top of the original comment. As for why they made such a big deal about "90 degree" lenses in the first place, I never could figure that out. As mentioned above, it is almost as wide as a 20mm lens, but I never felt that 20mm lenses were really that popular. Are they?

From a mathematical point of view, it actually is a bit special. If you read my calculation, it is correct. But it only works for a 90 degree field of view. For any other field of view, you need the more complex formula that someone else posted. So for Pythagoreans (people who worship mathematics), the 90 degree lens might be "holy", or something like that. I don't know, I'm not a Pythagorean.

 

[RAZKY]

What was special about a 90 degree lens? Photographically, nothing as far as I'm concerned, it is just another "ultra-wide". The problem was that about 5 - 6 years ago, "GitUp" was calling 3 different lenses with 3 different focal lengths all "90 degree" lenses, and I had to figure out which one was right. As it turned out, their 3.85mm lens was almost 90 degree when used for still pictures (full sensor), but even that one was not "90 degree" when used for 16 x 9 video, so my opinion was that none of them was actually a "90 degree" lens. The other focal lengths were roughly 4.1mm and 4.35mm. That's what I described in the other topic which I mentioned right at the top of the original comment. As for why they made such a big deal about "90 degree" lenses in the first place, I never could figure that out. As mentioned above, it is almost as wide as a 20mm lens, but I never felt that 20mm lenses were really that popular. Are they?

From a mathematical point of view, it actually is a bit special. If you read my calculation, it is correct. But it only works for a 90 degree field of view. For any other field of view, you need the more complex formula that someone else posted. So for Pythagoreans (people who worship mathematics), the 90 degree lens might be "holy", or something like that. I don't know, I'm not a Pythagorean.

What was special about a 90 degree lens? Photographically, nothing as far as I'm concerned, it is just another "ultra-wide". The problem was that about 5 - 6 years ago, "GitUp" was calling 3 different lenses with 3 different focal lengths all "90 degree" lenses, and I had to figure out which one was right. As it turned out, their 3.85mm lens was almost 90 degree when used for still pictures (full sensor), but even that one was not "90 degree" when used for 16 x 9 video, so my opinion was that none of them was actually a "90 degree" lens. The other focal lengths were roughly 4.1mm and 4.35mm. That's what I described in the other topic which I mentioned right at the top of the original comment. As for why they made such a big deal about "90 degree" lenses in the first place, I never could figure that out. As mentioned above, it is almost as wide as a 20mm lens, but I never felt that 20mm lenses were really that popular. Are they?

From a mathematical point of view, it actually is a bit special. If you read my calculation, it is correct. But it only works for a 90 degree field of view. For any other field of view, you need the more complex formula that someone else posted. So for Pythagoreans (people who worship mathematics), the 90 degree lens might be "holy", or something like that. I don't know, I'm not a Pythagorean.

Is there any way you can provide a sensible explanation for this post?

 

[480sparky]

Whatever gobblegook you're referring to with a 90° FOV lens also applies to.... well.... every lens ever made. Changing the aspect ratio of the final image/video will change the FOV.