Sony lenses are EXPENSIVE!!!

[andrew robertson]

Robert, get it straight. A 15mm lens is a 15mm lens is a 15mm lens. The focal length

does not change depending on what camera you mount it on - that's a physical property

of the lens. Nor can a fisheye become a rectilinear lens if you mount it on a cropped

camera. It's the same lens, projecting the same image circle, but you simple see less of it

because the imaging plane has less area.

 

And fisheyes don't have 'barrel distortion'. They produce an orthographic projection,

which is completely different. Get it straight, and I am amazed that you continue to insist

that you are right when you're dead wrong.

 

A lens does not change focal length depending on the size of the imaging plane, and a

fisheye cannot become a non-fisheye. A fisheye lens is a fisheye lens no matter WHAT

camera you mount it on.

 

As you are quite obviously confused, I would suggest reading about what the crop factor

is. I assure you that you are very wrong, and again, you come off like quite a fool by

insisting that a fisheye lens can somehow magically become a non-fisheye simply by

mounting it on a camera with a smaller imaging area. As I said above, you wouldn't take a

picture made with a fisheye lens, crop the edges off, and claim it was rectilinear, would

you? But this is what you insist.

 

By the way, did you even read the Wikipedia article you referred me to, or the one I liked to

above? If you had, you'd perhaps realize that you have some learning to do.

[andrew robertson]

"Just another case of you not being able to back-up your statements."

 

I hate to get personal here, but it's clear that you are resorting to freshman level sophistry

to attempt to bolster your case. This makes you out to be a bigger fool than your

mistaken insistence that a fisheye can magically become another type of lens when

cropped.

 

You have a lot of learning to do. Learning about what a crop factor is, and what it does,

will help you out a lot. I'm not sure you will admit that you are in error, as your

childishness is quite evident from your style of debate, but I assure you that the more you

insist that you're right the sadder you become. Whoever taught you photography has a lot

of apologizing to do.

[andrew robertson]

Again, I will tell you as simply as I can, using only small words this time.

 

A fisheye lens does not need to have an angle of 180 degrees or more. The angle of view

doesn't have anything to do with whether or not a lens is a fisheye.

 

A fisheye is a lens that produces a hemispherical projection (often orthographic). That's it.

No angle of view requirement. And it is not the same as a wide angle lens with heavy

barrel distortion. I can't get any simpler than that.

 

http://www.zeta.org.au/~andrewa/ajaa31.htm

 

http://www.photo.net/learn/fisheye/

 

Reading these should convince you that you are quite wrong indeed. Remember, there is a

difference between an image with a hemispherical projection, and a rectilinear lens with

barrel distortion. A fisheye is a fisheye even if you mount it on a camera with a 20x crop

factor, because the size of the imaging plane does not affect the projection the lens

renders.