wide angle lens question

[jeff_scott5]

I am just curious why the Pentax 10-17mm and the Sigma 10-20mm lenses are so

very different. The Pentax 10-17mm has a 180*-100* angle of view and the Sigma

10-20mm has only a 102.4* - 63.8* angle of view. Both are labled as Digital

only. Can some one explain the differences to me?

[andrewg_ny]

The Pentax 10-17mm is a fisheye design with high distortion while the Sigma is a rectillinear design. The Pentax DA 12-24 is a closer match in lens type to the Sigma. If you look at sample photos taken with a fisheye lens, the difference will be obvious.

 

-Andrew

[renatoa]

I want to add a question: if you de-fish, i.e. made rectilinear a fisheye picture, how is the image compared with one taken using a rectilinear lens/zoom of the same focal?

 

I found this link:

 

http://www.pbase.com/vernix/wide_angle_comparison

 

Unfortunatelly there are drawn coverages only for 12mm up, I am curious if someone can draw on these pictures the coverage rectangle for a rectlinear 10mm lens, in this case Sigma 10-20 @ 10mm.

[michael_kuhne]

The fisheye design does indeed have a much wider angle of view for the same focal length, but with the fisheye distortions. The wide angle perspective distortions especially at closer shooting distances, are much more noticeable on the 10-17mm digital version than on the 17-28mm film-based version at the same angle of view. But that can make for more fisheye fun.

 

Renato raises a very interesting question! I am a photoshop beginner, but I have read that distortions of various kinds can be corrected in photoshop. I would like to know how, and can it be done in Elements as well as CS?? As Renato implies, that could result in fantastic wide angle results using the fisheye zoom lens, either the digital or film-based model.

[jeffpolaski]

I shoot with a CV Bessa L and a CV 15mm rectilinear lens. From the example shown in the above link of the ship deck, Photoshop does a good job of correction. However, notice the far right and left sides, in which the size of objects is somewhat larger than the eye would expect.

 

This also happens with the CV Voightlander 15mm ultrawide, which is a true rectilinear. The task I have set myself is to minimize this effect with composition.

 

Conclusion, if a decent fisheye is already in your bag, you can correct it in PS. But I personally wouldn't go out and buy a fisheye just for this purpose.

[sonbou_abc]

I don't know how to correct distortion with photoshop. I tried "edit>transform>perspective" but it didn't work as I expected.

Look at:

http://www.powerretouche.com/Lens-distortion_plugin_introduction.htm

[guido_sardella]

No, you can't use the tranform->perspective in Photoshop to correct fisheye perspective, you

need things like Phototools, PTGui, Proxel, that give you a panoramic image. Or try Fisheye-

Hemi, that corrects the image in a sofisticate way, inside the 2/3 ratio of the original image,

without introducing distortion to object in the sides.