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DSLR fisheyes


nswelton

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If you want a real fisheye look, most people get the Peleng 8mm manual focus fisheye which can be found in an EOS mount or adapated from M42. A web search will dig up lots of references.

 

I have heard no rumors of a true fisheye for APS-C sensor EOS bodies (the 15mm Canon fisheye loses much of it's "fisheye" look on APS-C cameras). A true 180 degree diagonal fisheye would be a logical lens to make in an EF-S mount if Canon are planning more EF-S lenses, but I don't think anyone knows if or when that might happen.

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I think he presumed that canon DSLR mean the DSLRs with 1.3x factor(1.3 x 8mm = 10.4)... probably he is using a 1D range DSLR.. On all lower end DSLRs 8mm would equate to 12.8mm...

 

Dont know how the sigma 8mm works on the DSLRs but on my film cams it works great.. I got a brand new for just a $100 more than peleng lens, so I opted for it..

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Do you think you got the math wrong?

<P>

An 8mm circular fisheye gives 180 degrees field of view. The

Nikon 10.5mm circular fisheye also gives the same 180 degree

field of view. So does the Canon EF 15mm fisheye lens.

<P>

Saying that an 8mm fisheye "becomes" a 12mm fisheye is meaningless,

since it is misuing the 1.3x or 1.6x sensor factor, which only

makes sense when applied to rectilinear lenses.

<P>

For fisheye lenses, the math is quite different. The field of

view is calculated as a fraction of the image circle. For the

Sigma 8mm f/4 EX circular fisheye lens, the image circle is

22.08mm in diameter.

<P>

If you put an EOS 20D 15mm x 22.5mm sensor behind that lens,

you would get a field of view that is cropped top and bottom.

The horizontal frame contains the 22.08mm diameter, so the

field of view is still 180 degrees. However, the vertical

extent of the frame is limited to 15mm, so the field of view

would only just over 122 degrees.

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