wide angle vs fish eye

[invisible]

The bendy look is quite appealing in pictures, but i guess it would get a bit tiresome if used all the time...

A fisheye is definitely a "specialty" lens that you should break out on a need basis only, or sparingly for a cool effect. If you abuse it, both you and your audience/clientele get tired.

I see you have the Nikkor 10.5 in your repertoire Sparky...

Best price i can see online for that one is £436....

A bit pricey for me to be honest, so a cheaper alternative will be the order of the day.

I haven't tried any of these, but they have pretty good reviews and are very reasonably priced (though they aren't autofocus): Amazon.com: Rokinon FE8M-N 8mm F3.5 Fisheye Lens for Nikon (Black): ROKINON: Camera & Photo

 

[BrianV]

I "just had to do the math" on this one...

The field of view for a "rectilinear" lens is just dependent on the focal length and size of the image sensor. Most "FOV"'s that are listed with a lens are based on the diagonal of the image sensor. It's "simple high-school geometry". It is the angle that you get from the edge of the sensor pointed across a point sitting above the middle of the sensor, the focal length is the distance sitting above the sensor. A 50mm lens on a full-frame sensor has a 46degree field of view, diagonal is ~43mm, look through a point sitting 50mm from the center- get the field of view.

With a Fish-Eye lens, the field-of-view is from curves passing through the "focal Length" point, not lines. The amount of curvature is the "distortion". The important number to know for a fisheye, is the amount of distortion.

 

[Helen B]

I "just had to do the math" on this one...

With a Fish-Eye lens, the field-of-view is from curves passing through the "focal Length" point, not lines. The amount of curvature is the "distortion". The important number to know for a fisheye, is the amount of distortion.

Not sure about 'curves passing through the focal length point'. They are really angles between two straight lines, not curves. Of course most fisheye lenses, as with other very wide angle lenses for SLRs, do not have the light that forms the image passing through the 'focal length point'. The concept of some lenses having distortion and others not can get a bit weird, unless you are taking a picture of a perfectly flat surface parallel with the image plane. I'm happy to go into this further if anyone is interested - my guess was that nobody would be interested.

 

[Patrice]

Not sure about 'curves passing through the focal length point'. They are really angles between two straight lines, not curves. Of course most fisheye lenses, as with other very wide angle lenses for SLRs, do not have the light that forms the image passing through the 'focal length point'. The concept of some lenses having distortion and others not can get a bit weird, unless you are taking a picture of a perfectly flat surface parallel with the image plane. I'm happy to go into this further if anyone is interested - my guess was that nobody would be interested.

Please do, your posts are very informative and well worth reading. Sometimes twice! You have a knack for explaining the technicalities in a progressive and logical manner while keeping the language understandable. You could be a lecturer.

 

[BrianV]

"They are really angles between two straight lines, not curves."

I was trying to think of a way to "visualize" the fisheye, the distortion is less at the center, more are the edges. I am guessing: It is not a constant angle across the field of view.

The most that I've done with it: put some extra optics (from taking apart a junk lens) onto a Nikkor 20/3.5 non-fisheye, make it into a fisheye. The FOV increased past 180degrees, got part of the house in back of the camera.

So as I understand it: fish-eye images are formed using bent-lines, rather than straight lines, the bend of the angle changes as you get further to the edges. I'm sure there must be software that corrects for the Fish-Eye distortion if someone wanted to.

 

[Helen B]

Yes, there is software that corrects for the fisheye projection, including some that does partial correction, which can be more pleasing than full correction at extreme angles (ImageTrends Hemi-Fisheye - link).

More later.

 

[480sparky]

Capture NX2 will correct both the 10.5 and 16mm fisheyes. But ONLY those lenses.