[SupremeMoFo]

At 10mm it's a 180 degree fisheye - what is it at 17mm?

[barondla]

At 10 it is a 180 degree fisheye. As you zoom it becomes less than 180 degrees.The angle of view is reduced. You no longer have to be as careful about getting your feet in the picture. It still has the fisheye distortion but it isn't as noticable. It is a fun lens. Hope this helps
thanks
barondla

[SupremeMoFo]

Damn, that sound attractive. Thanks! Now I want one.

[Ole]

At 10mm it's a 180 degree fisheye - what is it at 17mm?

It's about 100 degrees at 17mm.

Note, these angles of view are meassured diagonally, not horizontally. Anyway, you can stich more photos for an angle of view exceeding 180 degrees! Here's a link to a photo where I did just that - we were walking on a pretty much straight path coming from the left and continuing to the right:

Panorama stiched together of three overlapping images taken at 10mm

[little laker]

Very interesting picture Ole, I would have never guessed it was a straight path if you hadn't told me

I have to take some time and start working on pano's again

[hll]

what is the widest focallength without distortion???
as far as i remember, it is 14 mm??? (35mm equi 21mm)
am i wrong???
thank you...

[SpecialK]

what is the widest focallength without distortion???
as far as i remember, it is 14 mm??? (35mm equi 21mm)
am i wrong???
thank you...

It distorts at all focal lengths. At 10mm I have to be conscious about my left elbow which sometimes gets in the shot.

Here are some samples. First two at 10mm.

http://i133.photobucket.com/albums/q78/KylePix/061118-23Park.jpg

http://i133.photobucket.com/albums/q78/KylePix/061125-392GCTramBoy.jpg

and two at 17mm.

http://i133.photobucket.com/albums/q78/KylePix/061118-35Boats.jpg

http://i133.photobucket.com/albums/q78/KylePix/070203-3588LaneFireboat.jpg

[khardur]

Panorama stiched together of three overlapping images taken at 10mm

Ole, that's an awesome picture...! I really liked that one. Thanks for sharing.

[hll]

thank you very much for information and pictures

[jnorth]

Damn, that sound attractive. Thanks! Now I want one.

It is attractive. But you don't want one. Nope nope nope. You NEED one.

I used to think I wanted to add a fisheye to my collection. It had been on my imaginary LBA list for years. Then one day the Pentax rep for my area was in my local shop with some ~24" sized images taken with the 10-17. Within a couple weeks I moved it to the top of my LBA list and then checked it off the list. After using it for a bit I found that I didn't want one after all. I found that a fisheye lens was something I needed in a kit. The only blessing was that I didn't have one already that I needed to replace with the 10-17.

[d.bradley]

what is the widest focallength without distortion???
as far as i remember, it is 14 mm??? (35mm equi 21mm)
am i wrong???
thank you...

Rectilinear corrected lenses (non-fisheyes) distort, but they distort 'area' rather than 'lines'. For example, people at the edge of a frame of a rectilinear corrected lens look 'fat' while someone at the edge of a fisheye frame will look 'bendy' and kind of skinny usually!

Anyway...the Sigma 10-20mm is rectilinear corrected, so 10mm is about the widest lens 'without distortion' that I know of that is generally available. But it's for APS-C only.

14mm I think would be the widest Full Frame rectilinear prime...the Sig 12-24mm is rectilinear corrected and FF IIRC...

[d.bradley]

Now...I asked this question on another board and didn't get a full answer. If someone can tell me how a 17mm lens can be a 180* lens, and a 8mm or a 15mm lens can also be 180* FOV....and how that relates to linear distortion, I will be forever greatful.

[egordon99]

I don't recall anyone saying that ANY lens is 180 degrees @ 17mm.... The 10-17mm is 180 degrees at 10mm on an APS-C sized sensor.

Remember, the field of view is determined by both the focal length AND the sensor/film size. What was the answer you got on the other board and what didn't you understand about it?

Now...I asked this question on another board and didn't get a full answer. If someone can tell me how a 17mm lens can be a 180* lens, and a 8mm or a 15mm lens can also be 180* FOV....and how that relates to linear distortion, I will be forever greatful.

[blende8]

I once estimated roughly the horizontal field of view:

mm - HFOV
10 - 137 degrees
11 - 120
12 - 107
13 - 100
14 - 95
15 - 92
16 - -
17 - 85

[d.bradley]

I don't recall anyone saying that ANY lens is 180 degrees @ 17mm.... The 10-17mm is 180 degrees at 10mm on an APS-C sized sensor.

Remember, the field of view is determined by both the focal length AND the sensor/film size. What was the answer you got on the other board and what didn't you understand about it?

Lets take a smaller example...forgetting the 10-17 fisheye zoom for the moment since it's APS-C.

A link to a page on the 8mm sigma circ fisheye:
[url=http://www.sigmaphoto.com/lenses/lenses_all_details.asp?id=3319&navigator=4[/url]

Here's a link for the 15mm Sigma Fisheye:
Sigma - Lenses

And here's a link to my 17/4 Fisheye Takumar:
Die Cast Pro - Super-Fish-eye Takumar 17mm f/4.0

All say that FOV is 180* at 8mm, 15mm, and 17mm respectively. My question is how distortion is the variable, and related to the constant FOV at these different focal lengths.