Fisheye vs wideangle focal range

Hello,

I am thinking of buying a fisheye lens and am trying to understand the optics.

It seems that a wide angle lens with the same focal length as a fish eye lens has a narrower field of view.

I always thought that the focal length of a lens determins the field of view, but it seems that there are other lens features in a fisheye lens

that causes it to have a 180 degrees field of view. Am i right and and what is the most important difference between a wide angle and

fisheye lens of the same focal length?

Thanks,

Rob

<p>A normal (non fisheye) lens is a "rectilinear" lens.<br>

http://en.wikipedia.org/wiki/Rectilinear_lens</p>

<p>A rectilinear lens will attempt to keep straight-lines straight, but will distort the size of objects near the edges.</p>

<p>A fisheye lens maps the view completely different. It makes no attempt to keep straight-lines straight, but will distort the size of objects near the edges less.</p>

 

<p>Rob,<br>

I recently traded in a Nikon 10.5 f2.8 Fisheye lens to Igor's Camera Exchange. It is mint/as new. I only used it about 4 times. I think he is asking 510.00 for it if your interested.</p>

<p>Focal length is only relevant to a rectilinear projection lens, i.e. one that projects rectangular subjects with straight sides and right-angled corners, similar to a pinhole lens.</p>

<p>A fisheye lens can project anything from a full-frame image with strong barrel distortion, to a fully circular image. The angle included by a fisheye can be even greater than 180 degrees. I think the largest angle I've seen available is 220 degrees, so the lens can effectively look behind itself. "Focal length" (however that's defined in a fisheye) usually ranges from 16mm down to 6mm for lenses usable on 35mm film or full-frame.</p>

<p>I'd actually think very carefully before pouring money into a fisheye Rob. While they can give unique and startling images, the novelty soon wears off, and most fisheyes end up being traded, like Todd's, or lying unused. Image quality usually leaves a lot to be desired too.</p>

<p>Rodeo Joe's comments are appropriate here. A true fisheye lens is a very different creature from a rectilinear wide angle. Some software tricks can, so to speak, "unpack" fisheye images, but a wide rectilinear lens is far more useful for most people. The fisheye is a kind of one-trick pony, and you have to like that trick a LOT if you use the lens much.<br>

If you just want to play with the fisheye effect, this is one place where some of the fisheye attachments that screw into another lens may serve well enough, and for a lot less money. A few of them, like the old Spiratone 0.17X adapter (<a href="/classic-cameras-forum/00WndY">link</a>) can be surprisingly adequate stopped down.</p>

<p>I rented one for a weekend. Although it was fun for the weekend, by the end I knew I didn't want to own one.</p>

<p>Right now I am really enjoying my fisheye. Like any ultra-wide you have to learn how to use them. Just shoving them on the camera in order "to get it all in" is not the way to use them (nor is it really the way to use any ultra-wide in my opinion unless you are simply documenting something). The major plus of a fisheye is that distortion of people in the frame is much less worrying than with an ultra-wide. I have the full frame (non-circular) Sigma 15mm and the quality is actually very good, but you do need to stop it down, and you need to accurately focus despite the huge depth of field to get the best out of them. Also I generally use a 24 or 28mm as my wide angle, so when I want to go wide I am looking for a radically new view - a 180 degree full frame fisheye is just the ticket for this.</p>

<p>I have to say I don't much like circular fisheyes- I agree that those are <em>real</em> one trick ponies.</p>

<p>using a fisheye is tricky. you have to love exaggerated perspectives. it's not going to work for everything and if you are even asking this question, that's probably a good indication that a regular ultrawide would be better for you.</p>

<p>that said, a fisheye can be a good choice for specialized photography. it can work great for live shows if you are close--very close--to the action. but you have to be careful about what you put into the frame and really watch the edges. fisheyes also work good for panoramic landscapes in conjunction with stitching software.</p>

<p>i shot a couple of live events with my 15mm fisheye (on an FX camera) this past weekend. here's an example:</p><div></div>

<p>one more.</p><div></div>

<p>and here's an in-your-face shot.</p><div></div>

<p>A full frame fisheye does not have to be a one trick pony. My 16/3.5 AI's (yes I have two) are one of my most used lenses. The optical quality is outstanding even on my D800 - and I'm a stickler for sharpness.<br>

It can take a while to learn how to use a fisheye effectively - I think many people either don't get over the sharp part of the learning curve fast enough or ultra-wide is just not their thing and they end up selling it fairly soon.<br>

Here's some pure myths:<br>

- "Fisheye's are a fun-house/one-trick pony kind of lenses": Completely not true if one learns how to use one effectively. A fisheye can make some very weird images, but if used appropriately they can make some outstanding/non-weird images.<br>

- "You don't need to worry about focusing a fisheye": Only true if you use a low MP camera or don't print large or don't crop. On my D800 I certainly need to critically focus if I want sharp images. BTW traditional DOF scales are very optimistic. Wide open my 16/3.5 needs to be focused carefully if I want to post or print anything larger than a 4x6.<br>

- "Fisheye's don't have high optical quality": Certainly true that some do not, but many are excellent (some even wide open). The 16/3.5 AI Nikkor is hands down one of my sharpest lenses - even on my D800.</p>

<p>John</p>

<p>I guess how many "tricks" a fisheye is good for, sort of depends on your standards for new tricks. The idea of limited utility of a circular fisheye (particularly, I'll stipulate that the full or nearly full field ones are a little more useful) is not exactly a myth from the point of view of a "normal" user. ;)<br /> Top image here is the Nikkor 10.5 mm and the bottom is a strange 12mm Berolina fisheye (sold many places under various names, including Spiratone). Top image on Canon 20D (DX format), and the bottom on a Canon 5D.</p><div></div>

<p>You may also want to consider buying a fisheye that programs, like DxO Optics Pro, can convert to rectilinear. A fisheye can become very practical and useful when this option is available, allowing extreme wide-angle shots as below:</p>

<p><a title="Corrected 15mm room shot. by dcstep, on Flickr" href=" src="http://farm9.staticflickr.com/8095/8402168839_b669bf1207_c.jpg" alt="Corrected 15mm room shot." width="800" height="534" /></a><br>

Using software to have a dual purpose lens with one purchase is a great solution.</p>

<p>I think we have established that a fisheye is a great solution and not weird when used carefully! Also agree about the utility of de-fishing software, but it does show a characteristic shared with rectilinear ultrawides which I find worse than the distortion of a fisheye - the stretching of the edges.</p><div></div>

<p>still had the fish in the bag during today's shoot...</p><div></div>

Many thanks for the recommendations and information. It is true that I only have a couple of shots in my head that I would use the fish

eye for. I am working often with a 20 mm sigma on FX and a Tokina 11-16 mm on DX, but for some small projects I need the wider field

of view? I take the bended lines as something I will have to accept when i want to have a field of view of (near) 180 degrees. Or are there

normal wide angle lenses with this sort of field of view?

 

On nikon rumors, I saw this Zenitar for 200 dollar. Maybe this is any good.

Thanks ,

Rob

<p>Why not consider the Sigma 15-30 often selling for less than $400 on eBay? Gives an extremely wide angle of view and it's not fihy. I have it and the Sigma 15 fisheye and almost always grab the zoom.</p>

<p>Rob, you don't have to accept "bended lines" is you use de-fisheye software, like DxO Optics Pro with a lens such as Canon's EF 15mm f/2.8. See the example below, which shows straight lines out to the edges:</p>

<p><a title="Long, mahogany boat by dcstep, on Flickr" href=" src="http://farm9.staticflickr.com/8354/8403241604_8d556e9df7_c.jpg" alt="Long, mahogany boat" width="800" height="534" /></a></p>

<p>Here's the uncorrected boat shot:</p>

<p><a title="Untitled by dcstep, on Flickr" href=" src="http://farm9.staticflickr.com/8077/8402154519_4a8a30c050_c.jpg" alt="Untitled" width="800" height="534" /></a></p>

<p>Sigma 12-24mm is meant to be an interesting lens. Generally gets good reviews - low distortion for an ultra wide which is a good thing.</p>

<p>i have the sigma 15-30 too. sleeper FX UWA lens. but the 15mm fisheye takes up so little room in the bag.</p>

I see that the dxo software crops the shot quite brutely, to an extend that the field of view is even narrower than that of a wide angle lens

with the same focal range. Then why using a fish eye?

<p>Rob, you choose your lens based on the expected end result. In some cases you'll chose the 15mm fisheye and de-fish it with DxO or equivalent, or you'll shoot a multi-shoot panorama with your 24mm and stitch them together. Other times you may shoot with the fisheye and leave it fishy.</p>

<p>There may be de-fishing software that doesn't crop and instead stretches the corners. Pick your poison. I chose to frame the picture so that there's room to crop. It requires a little thinking ahead, but I like the end result of this method. Realize that with a fisheye lens, that adding crop room may mean stepping back less than a foot.</p>

<p>What's a good de-fishing software that doesn't crop? I'm curious to try it.</p>

Yeah, is there software that stretches without cropping. I'd be happy to see some example.

<p>Check the Fisheye-Hemi plugin. The free Hugin panorama software allows mapping to different projections. All projections, including the rectilinear, are odd at ultra-wide angles. The same problem as making a perfect flat map of the Earth ;)</p>