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Differences between the available fisheye lenses for the NX mount

Started Feb 11, 2015 | Questions
Jan Behrens Regular Member • Posts: 135
Differences between the available fisheye lenses for the NX mount
1

According to my knowledge, there are currently (at least) 4 different fisheye lenses available for the Samsung NX mount:

Note: According to my knowledge, the Samyang lenses are also sold under the brand names Bower, Rokinon, or Walimex.

They all seem to have a 180° diagonal angle of view. The original Samyang lens (which I also own) was occasionally praised for its nearly stereographic mapping [r=2*f*tan(phi/2)]. It's not completely stereographic though, since objects at the edge are slightly distorted (local distortion, which should be zero for a truly stereographic projection). I would assume that the real mapping function of the Samyang 8mm f/3.5 lens lies somewhere between a stereographic [r=2*f*tan(phi/2)] and an equidistant (linear) [r=f*phi] projection.

I assume that the Samyang 8mm T3.8 movie lens is optically equal to the Samyang 8mm f/3.5 lens, except that the aperture can be controlled continiously via the gear ring. Is this correct?

My second question is: What are the projections of the other fisheye lenses? Do they have a better projection (in the meaning of being stereographic), or a worse one? Is there somewhere a comparison chart? Does the Samsung fisheye lens have a projection that is close to being stereographic at all?

The f/3.5 and T3.8 fisheye lenses from Samyang seem much heavier than Samyang's f/2.8 fisheye lens. I assume this is because they were originally designed for camera systems with a longer flange focal distance. (The f/3.5 lens is also available for the Canon EF and Nikon F mount.) So my third question is: Has the heavier design of the f/3.5 lens any advantages or is it just a disadvantage due to design compatibility with systems that have a greater flange focal distance?

Regards
Jan Behrens

 Jan Behrens's gear list:Jan Behrens's gear list
Samsung NX1 Samsung NX 30mm F2 Pancake Samyang 8mm F3.5 Aspherical IF MC Fisheye Samsung 16-50mm F3.5-5.6 power zoom
ANSWER:
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ocphotodad Regular Member • Posts: 116
Re: Differences between the available fisheye lenses for the NX mount
1

Jan Behrens wrote:

According to my knowledge, there are currently (at least) 4 different fisheye lenses available for the Samsung NX mount:

Note: According to my knowledge, the Samyang lenses are also sold under the brand names Bower, Rokinon, or Walimex.

They all seem to have a 180° diagonal angle of view. The original Samyang lens (which I also own) was occasionally praised for its nearly stereographic mapping [r=2*f*tan(phi/2)]. It's not completely stereographic though, since objects at the edge are slightly distorted (local distortion, which should be zero for a truly stereographic projection). I would assume that the real mapping function of the Samyang 8mm f/3.5 lens lies somewhere between a stereographic [r=2*f*tan(phi/2)] and an equidistant (linear) [r=f*phi] projection.

I assume that the Samyang 8mm T3.8 movie lens is optically equal to the Samyang 8mm f/3.5 lens, except that the aperture can be controlled continiously via the gear ring. Is this correct?

My second question is: What are the projections of the other fisheye lenses? Do they have a better projection (in the meaning of being stereographic), or a worse one? Is there somewhere a comparison chart? Does the Samsung fisheye lens have a projection that is close to being stereographic at all?

The f/3.5 and T3.8 fisheye lenses from Samyang seem much heavier than Samyang's f/2.8 fisheye lens. I assume this is because they were originally designed for camera systems with a longer flange focal distance. (The f/3.5 lens is also available for the Canon EF and Nikon F mount.) So my third question is: Has the heavier design of the f/3.5 lens any advantages or is it just a disadvantage due to design compatibility with systems that have a greater flange focal distance?

Regards
Jan Behrens

These questions are over my pay grade. But I found two sources that might help a little:

http://erphotoreview.com/wordpress/?p=4930

http://www.dpreview.com/forums/post/55127611

 ocphotodad's gear list:ocphotodad's gear list
Sony RX10 III Nikon 1 S1 Sony a7R III Sony a7 IV Samsung NX 30mm F2 Pancake +9 more
OP Jan Behrens Regular Member • Posts: 135
Re: Differences between the available fisheye lenses for the NX mount

ocphotodad wrote:

These questions are over my pay grade. But I found two sources that might help a little:

http://erphotoreview.com/wordpress/?p=4930

http://www.dpreview.com/forums/post/55127611

Thank you very much for directing me to those two posts. They contain valuable information.

Jan Behrens wrote:

According to my knowledge, there are currently (at least) 4 different fisheye lenses available for the Samsung NX mount:

Reading your linked information, and rechecking the Samyang.pl website, I have to correct myself. Counting all second revisions, there seem to be the following 9 fisheye lenses:

  • Samyang 8mm f/3.5
  • Samyang 8mm f/3.5 II (second revision)
  • Samyang 8mm T3.8 (movie lens) (not for NX mount?)
  • Samyang 8mm T3.8 II (movie lens, second revision) (not for NX mount)
  • Samyang 8mm f/2.8
  • Samyang 8mm f/2.8 II (second revision)
  • Samyang 8mm T3.1 (movie lens)
  • Samyang 8mm T3.1 II (movie lens, second revision)
  • Samsung 10mm f/3.5

However, the movie lens with T3.8 doesn't seem to be available for the NX mount.

[...] What are the projections of the [...] fisheye lenses? chart? Does the Samsung fisheye lens have a projection that is close to being stereographic at all?

According to the article on erphotoreview.com, Samsung's fisheye lens is not stereographic. (Considering the same diagonal angle of view and the longer focal distance, this should have been obvious to me.)

[...] Has the heavier design of the f/3.5 lens any advantages or is it just a disadvantage due to design compatibility with systems that have a greater flange focal distance?

This question is still open. The first revision of the Samyang 8mm f/2.8 seemed to have optical deficiencies according to the article on erphotoreview.com, which have been fixed in the second revision. Does anyone know if this also applies to the first and second revision of the Samyang 8mm f/3.5 lens?

Regards
Jan Behrens

 Jan Behrens's gear list:Jan Behrens's gear list
Samsung NX1 Samsung NX 30mm F2 Pancake Samyang 8mm F3.5 Aspherical IF MC Fisheye Samsung 16-50mm F3.5-5.6 power zoom
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