[barondla]

Will the 10-17 fisheye zoom at 14mm on the K-1 look as fishy as a full frame 16mm fisheye? At 14mm would it cover a wider field of view? It's surprising how much wider at 14 this is vs the Pentax A series 15 rectilinear.
Thanks,
barondla

[pschlute]

Will the 10-17 fisheye zoom at 14mm on the K-1 look as fishy as a full frame 16mm fisheye? At 14mm would it cover a wider field of view? It's surprising how much wider at 14 this is vs the Pentax A series 15 rectilinear.
Thanks,
barondla

I will try and do a comparison for you tomorrow. I have the DA 10-17; K 15mm ; and A 16mm FE

[barondla]

I will try and do a comparison for you tomorrow. I have the DA 10-17; K 15mm ; and A 16mm FE

Cool! Can't wait to see the results. The 10-17 at 14 is considerably wider than my A 15 non fisheye. Did you buy the 10-17 for crop cameras then add the 16mm FE for K-1 full frame?

The 10-17 looses fishyness as it zooms towards 17 on a crop camera. Think less fishy means narrower field of view. Arghh, this gets confusing. I'll wait for your definitive test results.
Thanks,
barondla

[veato]

I think I read once that (on APS-C) the fisheye at 17mm still has a wider FOV than the Sigma 10-20 at 10mm.

[pschlute]

I think I read once that (on APS-C) the fisheye at 17mm still has a wider FOV than the Sigma 10-20 at 10mm.

Come again ?

How does a 17mm lens have a wider fov than a 10mm ?

[stevebrot]

Testing done by PF member indicate insufficient image circle at 14mm and shorter at all apertures. I would expect fishiness similar to that on APS-C but with little usable area to make a significantly wider composition.

We will see when Peter shows his work.


Steve

[veato]

Come again ?

How does a 17mm lens have a wider fov than a 10mm ?

I need to dig out the article as I don't recall the finer points, and it could have something to do with fisheye versus rectilinear, but I've just checked the specs and it looks like on paper the Pentax at 17mm is almost as wide as the Sigma at 10mm...

Pentax 180 - 100
Sigma 102.4 - 63.8

[stevebrot]

I need to dig out the article as I don't recall the finer points, and it could have something to do with fisheye versus rectilinear, but I've just checked the specs and it looks like on paper the Pentax at 17mm is almost as wide as the Sigma at 10mm...

Pentax 180 - 100
Sigma 102.4 - 63.8

This does not surprise me. Fisheyes are strange beasts and while the DA 10-17 has a much diminished FOV and "fishiness" at 17mm than at 10mm, it is still a fisheye and not bound to expectations of parallel or straight lines that rob rectilinear designs of FOV. One has only to spend some time on the Fisheye Fever club thread to realize that the DA 10-17 is a very wide lens at all focal lengths. Strangely, similar is true for the FF Sigma 15mm and Zenitar 16mm on APS-C.

Speaking of the Fisheye Fever club, I took a quick look there and found a DA 10-17 photo taken at 14mm on the K-1 in FF mode...

https://www.pentaxforums.com/forums/122-lens-clubs/33549-fisheye-fever-club-...ml#post4750751

From @fs999's Flickr...





Steve

[barondla]

Fisheye focal length numbers can't be directly compared to rectilinear numbers. On a crop body, the Pentax 10-17 at 10 is quite a bit wider than the rectilinear Sigma 8-16 at 8.

Just not sure how the Pentax 10-17 works optically. Does zooming up only crop the image, like any zoom, or do the optics correct fisheye distortion? Guessing the former.
Thanks,
barondla

[Sandy Hancock]

The field of view from DA10-17 @ 15mm on full frame is almost indistinguishable from the same lens @10mm on APS-C. The corners are sharper in the latter image of course.

Done four years ago with a film camera, over six months before the K-1 was released. APS-C @10mm on the left. Click on the images for a closer look in Flickr.



And I can confirm that at a given focal length, a fisheye is considerably wider than a rectilinear lens.

For example, the DA10-17 @ 10mm on crop is wider than the Sigma 8-16 @ 8mm



Even when de-fished in Lightroom, the fisheye @10mm is wider than the more-or-less rectilinear Sigma @ 8mm



Likewise, the DA10-17 @17mm and de-fished in Lightroom (thus losing some width) is almost indistinguishable from the DA15.

[pschlute]

Cool! Can't wait to see the results.

OK So these first 4 are all from the 10-17 zoom at 10/12/14/17 mm

[pschlute]

..... and these four are from the K15 A16FE K17FE K18 respectively

[pschlute]

I need to dig out the article as I don't recall the finer points, and it could have something to do with fisheye versus rectilinear, but I've just checked the specs and it looks like on paper the Pentax at 17mm is almost as wide as the Sigma at 10mm..

Indeed you are right. Thanks for pointing that out. Something I had never considered.

---------- Post added 10-14-19 at 02:37 AM ----------

We will see when Peter shows his work

Steve

Bringing you here in case you are interested.

---------- Post added 10-14-19 at 02:40 AM ----------

Thing I find amazing is how much distortion there is at the edge of the K 15mm 3.5 . Look at the pots at the bottom left. it has turned a circular into an oval !

[barondla]

Indeed you are right. Thanks for pointing that out. Something I had never considered.

---------- Post added 10-14-19 at 02:37 AM ----------



Steve

Bringing you here in case you are interested.

---------- Post added 10-14-19 at 02:40 AM ----------

Thing I find amazing is how much distortion there is at the edge of the K 15mm 3.5 . Look at the pots at the bottom left. it has turned a circular into an oval !

Technically the elongation at the edges isn't the fault of the K 15 ultrawide lens. Light travels farther to reach the edges of the sensor than center. Only way I know to fix this is to have a curved sensor (focal plane). Interesting stuff. Thanks again to everyone adding examples and knowlege.
Thanks,
barondla

[stevebrot]

Steve

Bringing you here in case you are interested.

---------- Post added 10-14-19 at 02:40 AM ----------

Thing I find amazing is how much distortion there is at the edge of the K 15mm 3.5 . Look at the pots at the bottom left. it has turned a circular into an oval !

Thanks! Yes, I saw that. A certain amount of residual distortion is not unexpected, but can be hard to correct.


Steve