Kamraman Loc: Canada

Hhhhhmmmmmm?

Peterff Loc: O'er The Hills and Far Away, in Themyscira.

A number of good responses so far. A few questions:

What is the widest lens you currently have?

What can't you do with your existing lenses?

Do you want the circular effect which is "very creative" but also limited by the same attributes?

Do you want an extremely wide lens (accepting barrel distortion - curves) that fills the frame?

Do you want an extremely wide lens (no barrel distortion - rectilinear / straight lines) that fills the frame?

If you do not already have a rectilinear ultrawide say Sony's DT 11-18mm http://www.bhphotovideo.com/c/product/439153-REG/Sony_SAL1118_SAL_1118_11_18mm_f_4_5_5_6_DT.html or similar that may be more versatile.

If you want a fisheye then the Samyang 8mm is affordable and worthy of consideration http://www.bhphotovideo.com/c/product/859140-REG/Samyang_SY8M_S_8mm_f_3_5_Fisheye_Lens.html

The images below give an idea of what the Samyang can do.

What kind of creativity do you want?

jerryc41 Loc: Catskill Mts of NY

Aside from the fact that they're not free, there's no reason not to get one. You can get some unique shots with them, but you can also get normal shots, depending how you hold them.

http://www.kenrockwell.com/tech/how-to-use-ultra-wide-lenses.htm

cmikal

I have a Nikon 10.5mm. It has a 180 field of view. I carry it with me all the time and use it when I think I might get a good shot from it. Occasionally, I walk around and just shoot with it to see what looks good at the end of the day. Many shots get tossed, but occasionally I get one that is a keeper, so for me, I'm glad I have it. I don't know if I will ever get a true 360 degree field of view fisheye, since I think it would get much less use and I would rather spend the money on something else. 360 might look fine on a monitor, but if you print it.....not so much. Attached is a pic that I took with the 10.5mm. The first has no lens correction applied. The second is the exact same photo with Lightroom's lens correction preset applied. You can see how it straightens out the incline lights and the other elements near the edges of the photo. It also crops the photo a bit so the image fits within the rectangular format without any dead space at the corners.

I personally like the original, since it has a bit of a different look to it than a standard wide angle photo, but I can also see the appeal of the corrected image too.

Lens view uncorrected


Lens view corrected using Lightroom preset

Kamraman Loc: Canada

I have to say I have indeed learned a lot from the answers to the original question of Fisheye or Not.

I was considering such a purchase too. But not knowing exactly what could/could not be achieved with this type of lens I held off on the buying.
Though I had a free hand lens that was fisheye type, look though the lens from the flat side or through the convex face gave different images.
The answers given by objective responders helped.