[Vranx]

If I use a rectangular 180 degree fisheye lens on a film body, I know it is 180 degrees angle of view. But on an APS-C body?

Is this calculated similarly as the crop factor for focal lengths? And can this be used for any lens and its angle of view?

What angle do I get from my 180° fisheye, focal length is 16mm, by the way?

Please enlighten me!

Thanks in advance,

Vranx

[Adam]

The DA 10-17mm fisheye gives you 180 to 90 degrees on APS-C. The FA 17-28mm, on the other hand, is hardly a wide-angle at the long end

[markkuk]

First you need to know which of the several possible fisheye projections is used by your lens. Often the projection is mentioned in the technical specs of the lens. Then you can just do the math using one of the equations on this page: Field of View Calculator - Rectilinear and Fisheye lenses - Bob Atkins Photography

[Na Horuk]

Are you thinking of any specific lens? Usually you can find this data online, either from the manufacturer or someone who calculated it.
If its a circular fisheye the crop won't be as drastic as if its a fisheye that covers the whole full frame. Also, not all fisheye lenses have 180 degree FoV
A good place to look for info might be the lens review database on these forums. Third party lenses here.

[stevebrot]

16mm fisheye? Do you have a Zenitar 16/2.8 by any chance?

I have been using that lens on APS-C for several years with good results. FOV with the Zenitar on APS-C is wider than with even a 15mm rectilinear lens. I would estimate it at about 120 degrees diagonal. The amount of fishiness on APS-C is highly dependent on lens orientation and the subject.

Here is a link to the Zenitar Fisheye photos on my Flickr stream. Note that there are both FF film and APS-C images in the mix. The difference is often obvious and sometimes not.

https://www.flickr.com/search/?w=28796087@N02&q=zenitar


Steve

[Vranx]

The lens in question is the old Sigma Filtermatic 2.8/16 mm Fish Eye lens. It has 180° field of view on a 35mm film camera and fills the rectangular 35mm frame (so it's none of these circular fisheyes where you have black outer parts around the circular images).

What I would like to find out is whether the angle of view is going to end up like a 24mm wide angle when I use it on a K5 II or whether the situation is different whith a fisheye. Somewhere I've read, that it is more difficult to determine the crop factor of the angle of view than of the focal lenth, because the angle of view has to be calculated using a tangens formula. With the focal length it is just linear, always factor 1.5.

Which means the changes are much more drastic on a super wide angle than on a super tele lens. Does anyone have the correct formula for the angle of view???

[markkuk]

Does anyone have the correct formula for the angle of view???

I gave you the link to the correct formulas in my previous post.

[kh1234567890]

The lens in question is the old Sigma Filtermatic 2.8/16 mm Fish Eye lens. It has 180° field of view on a 35mm film camera and fills the rectangular 35mm frame (so it's none of these circular fisheyes where you have black outer parts around the circular images).

What I would like to find out is whether the angle of view is going to end up like a 24mm wide angle when I use it on a K5 II or whether the situation is different whith a fisheye. Somewhere I've read, that it is more difficult to determine the crop factor of the angle of view than of the focal lenth, because the angle of view has to be calculated using a tangens formula. With the focal length it is just linear, always factor 1.5.

Which means the changes are much more drastic on a super wide angle than on a super tele lens. Does anyone have the correct formula for the angle of view???

Search for images taken with this lens on full frame. Flickr is a good start. Download some of them. Crop them to size. That is all that will happen when you use the lens on APS-C sensor. Then you'll know

[Lowell Goudge]

If I use a rectangular 180 degree fisheye lens on a film body, I know it is 180 degrees angle of view. But on an APS-C body?

Is this calculated similarly as the crop factor for focal lengths? And can this be used for any lens and its angle of view?

What angle do I get from my 180° fisheye, focal length is 16mm, by the way?

Please enlighten me!

Thanks in advance,

Vranx

Just to clarify this for us please. There is no such thing as a rectalinear fisheye. A lens is either rectalinear or fisheye.

Second field of view is related to format so a 180 degree field of view on full frame is not z180 degree field of view on APS-C. The actual field of view will depend on the amount of barrel distortion present. But a 180 degree fisheye on APS-C will likely give a 180 degree field of view circular image in the middle of a full frame Or maybe a little more with vignetting in the shape of the lens hood

We can't predict what you will get unless you tell the exact lens you are using

[boriscleto]

We can't predict what you will get unless you tell the exact lens you are using

And he did...

The lens in question is the old Sigma Filtermatic 2.8/16 mm Fish Eye lens. It has 180° field of view on a 35mm film camera and fills the rectangular 35mm frame (so it's none of these circular fisheyes where you have black outer parts around the circular images).

[Vranx]

I am sorry, it is of course not a rectilinear, but a true fisheye lens (Sigma Filtermatic 2.8/16 mm). I used the term wrongly to describe that it is not a circular fisheye.

Concerning the formulas in the link: I saw them but had the understanding (probably due to my limited English) that they describe the angle of view after doing some de-fishing with special software, which I do not intend to try.

[markkuk]

Concerning the formulas in the link: I saw them but had the understanding (probably due to my limited English) that they describe the angle of view after doing some de-fishing with special software, which I do not intend to try.

No, the formulas are for the actual fish-eye field of view. The example at the end of the article just shows how de-fishing maintains the same horizontal and vertical FOV, you can ignore that part if you don't intend to use de-fishing software.

[stevebrot]

The lens in question is the old Sigma Filtermatic 2.8/16 mm Fish Eye lens. It has 180° field of view on a 35mm film camera and fills the rectangular 35mm frame (so it's none of these circular fisheyes where you have black outer parts around the circular images).

You can use the formula for equisolid (most likely type) in the link provided by markkuk or simply photograph a meter stick at a known distance and dust off the high school trigonometry book.


Steve