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06-19-2014, 11:54 PM   #1
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Do all fisheye lenses have that curved look?

I imagine this may seem a pretty silly question to the experts but I am wondering since looking at wide angle lenses do all fish eye lenses have that curved looked? I wasn't sure whether to post this in beginners or lenses. I imagine the curve is why it is called fish eye but was just wondering if there was an exception to the rule.

06-20-2014, 12:00 AM   #2
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QuoteOriginally posted by Sorver Quote
I imagine this may seem a pretty silly question to the experts but I am wondering since looking at wide angle lenses do all fish eye lenses have that curved looked? I wasn't sure whether to post this in beginners or lenses. I imagine the curve is why it is called fish eye but was just wondering if there was an exception to the rule.
"Fisheye" basically means exaggerated distortion, so yes. The amount of distortion varies from lens to lens, however: for example at 17mm, the Pentax 10-17mm fisheye zoom doesn't distort the edges that much. If you don't want the effect, go for a rectilinear lens.

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06-20-2014, 12:25 AM   #3
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QuoteOriginally posted by Sorver Quote
do all fish eye lenses have that curved looked?
In general, yes - but you can get a rectilinear ('normal') look with some of them through careful composition.
06-20-2014, 12:28 AM   #4
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QuoteOriginally posted by Adam Quote
"Fisheye" basically means exaggerated distortion, so yes. The amount of distortion varies from lens to lens, however: for example at 17mm, the Pentax 10-17mm fisheye zoom doesn't distort the edges that much. If you don't want the effect, go for a rectilinear lens.
Thank you Adam I thought that might be the case at this stage a rectilinear it is although I can't remember which make I think Sigma or was it Pentax had an Art lens that looked super cool might be a buy for a whim rather than a need later on.

---------- Post added 06-20-14 at 12:29 AM ----------

QuoteOriginally posted by OregonJim Quote
In general, yes - but you can get a rectilinear ('normal') look with some of them through careful composition.
Ah that explains some shots I have seen that were listed as fisheye but looked near normal
Thank you

06-20-2014, 12:30 AM   #5
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Just to expand on Jim's point. If you have only limited straight lines, and/or the lines are on a line through the center of the frame, they will remain straight. It is only when you have lines that do not radiate out of the middle of the frame, such as taking a photo of a square box, that lines are distorted. You can even do landscapes to some extend with the horizon on the center line of the frame
06-20-2014, 01:25 AM   #6
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And there's "Defishing," where you attempt to correct the fisheye distortion.
The Malaysian Technographer: Defishing a Fisheye Lens. Starring the Samyang 8mm f2.8.

If I recall what I've read correctly, some lenses are *much* easier to defish than others. Stereographic projection vs equisolid or something like that.
06-20-2014, 02:07 AM   #7
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Basically you are trying to project the surface of a sphere onto a flat plane - something has got to give

Either you end up squashing the frame edges, as in fisheye, or stretching them, as in rectilinear. Or somewhere in-between as with all the other projections. The biggest problem are objects which we know should have certain proportions, such as people, so it is a god idea to keep those in the centre.
06-20-2014, 03:21 AM   #8
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QuoteOriginally posted by OregonJim Quote
In general, yes - but you can get a rectilinear ('normal') look with some of them through careful composition.
examples:
effect


no effect


Same lens (rokinon 8mm)

06-20-2014, 04:23 AM - 1 Like   #9
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All wonderful responses, however let me add a bit to the mix. Yes, all fisheyes - by their very nature (or more accurately, their optical projections) produce exaggerated distortions. What differs is how and to what extent do they exaggerated the distortion. Let's take one lens - the DA 10-17, primarily because its a zoom. At 10 mm - its view is very distorted - however, when zoomed to 17mm its view becomes quite complacent. I did a comparison a while back....Depending on the scene (its perspective) and what is in the scene, a fisheye can have a much more normal "look" than a rectilinear lens. This is especially true if the objects in the scene are natural - hills, bushes, etc. as opposed to a lot of rectangular buildings. You eye will quickly detect what does not look normal - regardless of the lens that is used. If something is out of proportion or curved or in-appropriately stretched or whatever - you will immediately see it.

Also, there is the case that I'll refer to as a un-intended mismatch. Take the Zenitar 16mm fisheye, its a full frame fisheye. However, when you mount it on a APS-C crop sensor camera body, you are only using the center of the lens, and effectively not able to record the extreme edges/corners of the lens' fisheye projection on the sensor (since the sensor is small than intended). This lens (with the body), does not really feel that "fishey".

Also, there is not just one - as in a single fisheye projection. There are nearly an endless variety of projections that can be used. Its the lens designer who selects the projection and the properties of the projection that is used. So, you can take two different fisheye lenses of the same focal length, and their "view" of the world can be completely different. You may like one, and hate the other. Let's again take the DA 10-17 at 10mm and the new Samsung 10mm (which is just becoming available). They will each have the same focal length, but I suspect that their projections will be different - to what extent, I don't know. It will be interesting to see a side by side comparison. Folks may like both, or wind up hating one or the other. Folks liking the current 10-17 may wind up liking it less and the Samsung more. Also, the treatment on one lens may work better for some view/scenes being shot that the other.

Here is a web site that has a lot of information on fisheye projections available to lens designers, and how they might use/apply them to varying degrees.Also, this site has a large set of interesting diagrams. Forget the math, just look at the figures and the light rays, in terms of how they are gathered from around the lens and then folded, spindled and mutilated to get them on to various parts of the sensor (center, edges and corners). It is amazing how far afield that they can grab the scene and pull it into the frame.Normally, I like the 10-17 - especially that way it treats landscapes. There have been a few times that I have shot images, where I have looked at them and the shot was a complete looser. Even with natural curves - the distortion did not work, it was not a pleasant view. Other images, its treatment was much better than expected. YMMV.

Ah - then there is de-fishing. I usually don't. Again YMMV. Here are a couple of webpages that I think effectively addresses defishing very effectively.Then there is the wild card - you the photographer, who will take what the lens designer has provided an apply it to the scene. You can do anything you wish, further exaggerating the distortions in various ways. Take the example above with the train - very effective in amplifying one particular view. Then take the lake view. Of the "no effect" shot, you can ever so slightly tip the camera either up or down from there and produce an exaggerated fisheye effect - I call it, where to place the bend or what to bend. In that shot there is a bend - if you know what to look for. Its down at the bottom. I would think that the shoreline is probably pretty straight at the photographer's feet - but you can't tell since the bend is gentle and natural, plus you don't actually know what the shoreline looked like at that location.
_________

Let me add one last thing here. Originally the fisheye was developed to get an image of the sky - clouds in a single frame. Its pretty effective at that. But, is the fisheye the most effective lens at middle to distance landscapes - well it depends (on you the photographer, and what you want to image). Its telling of a story. Fisheyes (and UWA lenses in general) are most effectively applied at near to middle distances. It is somewhat counter intuitive in terms of their use (but - again its up to you the photographer to apply the tools in any way that you please).


Last edited by interested_observer; 06-20-2014 at 04:44 AM.
06-20-2014, 05:17 AM   #10
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QuoteOriginally posted by interested_observer Quote
Ah - then there is de-fishing. I usually don't.
The problem with getting a fisheye is that after you've taken all the usual shots it gets boring. De-fishing brings back some of the fun into it.










Not as much as taking 360 degree panos though
06-20-2014, 11:35 AM - 1 Like   #11
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Distortion is such a loaded term. A fisheye image is only distorted if you are expecting straight lines. A rectilinear ultra-wide image only lacks distortion if you don't mind stretched proportions.

I shoot extensively with a Zenitar 16/2.8 fisheye on my APS-C cameras. The Zen was designed for 35mm film and allows 180 degrees diagonal FOV with that format. On APS-C, the FOV is closer to 120 degrees. That means no fishy on APS-C, right? No, not at all. The Zen still has a circular projection regardless of what part of the image circle you sample. Conversely, it is wrong to assume that the circular projection will always result in bent lines. Lowell is absolutely correct in his comments above that the orientation of the lens axis to straight lines in the frame determine their "straightness" and how fishy the photo will appear.

It is also good to note that in the absence of anticipation of straight lines, fishy disappears entirely! The shot merely looks wide instead.

Here is an example (APS-C with the Zenitar) where obvious visual cues to fishy are missing:




Here is are two examples (APS-C with the Zenitar) where the orientation of camera to subject foils the fish:






Two examples of very fishy (APS-C with the Zenitar):






And a few very fishy on 35mm film with the Zenitar


Helped along by the presence of multiple very curved lines in the scene




And finally a few 35mm shots with the Zenitar (none de-fished) that don't look particularly fishy at all:







Have we seen enough photos yet? None of the above have been straightened or bent in PP. To give an honest evaluation, my Zenitar fisheye is one of the most versatile components of my working kit. For completeness, I should add that I also own the Rokinon (a.k.a. Samyang, Bower, Vivitar, etc) 8mm fisheye. It provides a full 180 degrees FOV on APS-C. Unfortunately I use it pretty much exclusively for the fisheye effect and seldom as a general purpose ultra-wide and have no minimally fishy examples. I will try however.


Somewhat less fishy with the Rokinon 8mm on APS-C






Very fishy with the Rokinon 8mm on APS-C





Yes, those are my feet in the last photo.


Steve

---------- Post added 06-20-14 at 11:57 AM ----------

QuoteOriginally posted by interested_observer Quote
Depending on the scene (its perspective) and what is in the scene, a fisheye can have a much more normal "look" than a rectilinear lens.
This is so true. We actually expect a certain amount of curvature if the perspective is very wide and particularly if the viewing distance is close relative to the size of the final image. The lens in the human eye, after all, does not provide a rectilinear projection, but then again, it does not project onto a flat surface either.

QuoteOriginally posted by interested_observer Quote
Also, there is not just one - as in a single fisheye projection. There are nearly an endless variety of projections that can be used. Its the lens designer who selects the projection and the properties of the projection that is used.
This was immediately apparent to me when I got my Rokinon 8mm fisheye. I had been shooting for years with the Zenitar which has a fairly straightforward and very predictable projection. The Rokinon, on the other hand, features what Samyang calls stereographic projection. One can argue as to whether it is truly stereographic, but it is definitely different from most fisheyes and hard to predict.


Steve

Last edited by stevebrot; 06-20-2014 at 11:43 AM.
06-20-2014, 01:17 PM   #12
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QuoteOriginally posted by kh1234567890 Quote
The problem with getting a fisheye is that after you've taken all the usual shots it gets boring. De-fishing brings back some of the fun into it.
I should have qualified the statement a bit more. I usually don't defish because a lot of what I use the fisheye on does not defish that well. Its really dependent upon the subject matter and the perspective. Also, if you plan to defish the image, you should probably frame it well in from the borders, so that when you defish and crop you actually wind up with the shot that you intended.

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