I'm sure this has never been done before 😉 -- but since I received my Lawla 10mm MF lens for Canon RF and Kenko 2x TC today, I figured I'd do a quick and dirty comparison at the rectilinear and fisheye field of view. Sharing it here in case it's helpful for others to visualize what you get with each type of lens and extreme rectilinear lenses in the 10mm range.

 

All these images are taken with same setup I've been using recently to test strobes (and, indeed, are at F22, ISO 100 with an Ikelite DS230 firing at full power). Distance from camera to the front wall is 1.4m. 

 

First, the rectilinear lenses. 10mm, 14mm, 15mm, 16mm, 17mm, 20mm

 

 

There's a pretty obvious jump in coverage from 14mm to 10mm. The difference between 16mm, 15mm and 14mm is not so dramatic. 

 

Now for the fisheye lens, Canon 8-15mm, at 8mm, 15mm, and then 16mm (8mm + 2x TC). And each of those focal length de-fished using lens corrections in Lightroom.

 

 

 

If you're going to de-fish the fisheye, do it at 15mm, not 8. While you do get a wider angle of view defishing a circular fisheye, the loss of resolution at the edges is pretty extreme. At 15mm, the de-fished image is acceptable in quality dowscaled to 1500 pixel, at least for web/social media use.

 

The 15mm fisheye image de-fished is  has a wider field of view than 14mm rectilinear - but closer to the 14mm  field of view than the 10mm rectilinear.

 

At the opposite end of the spectrum, here is the fisheye + 2x TC at 30mm  between the 28mm and 30mm rectilinear. They're very close -- I guess basically same as a 29mm rectilinear lens. Note that the rectilinear is marginally narrower horizontally but wider vertically. At 30mm, the fisheye only shows a mild amount of fisheye distortion. 

 

 

And here is the 30mm fisheye de-fished next to the 30mm rectilinear. Not much between them in terms of angle of view.

 

 

My conclusion is that the fisheye lens at longer focal length converges on the same angle of view as a rectilinear lens. This is especially once you de-fish it. 

 

Further, the 8-15mm + 2x TC combo gives has a very versatile range. It goes from a diagonal angle of view of 170 degrees at 16mm and 73 degrees at 30mm. That's very similar to the 170-74 degree angle of view Nauticam advertises for the FCP + Sony 28-60 combo. 

 

I'll take some shots with my WWL-C and 24-50 lens to see how the Nauticam conversion lenses fit into the bigger picture. 

 

 

Edited June 19, 20242 yr by DreiFish
Reducing image size to try to condense the post.

Here are the results with the WWL-C (in air.. perhaps it's a bit more zoomed in in water?)

 

At the wide end (24mm on the base lens), Nauticam rates it as similar to a 10mm rectilinear lens, and it sorta is. Same horizontal field of view, but the rectilinear lens has a taller vertical field of view.

 

 

Zoomed all the way (50mm on the base lens), it closely matches the field of view of the 35mm rectilinear lens. This is despite Nauticam stating it should behave more like a 21mm lens. 

 

 

So I'd say it's a bit more versatile than the 14-35mm lens, if you can live with the barrel distortion.

This should be a pinned article or something.

On 6/20/2024 at 1:22 PM, DreiFish said:

Here are the results with the WWL-C (in air.. perhaps it's a bit more zoomed in in water?)

 

At the wide end (24mm on the base lens), Nauticam rates it as similar to a 10mm rectilinear lens, and it sorta is. Same horizontal field of view, but the rectilinear lens has a taller vertical field of view.

 

 

Zoomed all the way (50mm on the base lens), it closely matches the field of view of the 35mm rectilinear lens. This is despite Nauticam stating it should behave more like a 21mm lens. 

 

 

So I'd say it's a bit more versatile than the 14-35mm lens, if you can live with the barrel distortion.

 

You can just take a constant zoom ratio (50/24 * 10 = 21) but that doesn't hold between fisheye projections and rectilinear ones.  I did some calculations and it appears that the WWL-C follows something close to a stereographic fisheye projection and you can calculate horizontal and vertical field from that:

 

What Nauticam quotes is a 130- 72° diagonal field which is equivalent to the diagonal field of 10-30mm lens, if you compare the horizontal fields it matches the field of a 12.2 - 31mm lens with a slightly smaller vertical field. 

@DreiFish you are such a darling! Many thanks for putting the time + brain + energy in this.

 

I have one more question:

 

Will a 1.4x TC show some black vignetting on the Canon 8-15 Fisheye @ 8mm ?
 

Maybe somebody owning a canon fullframe body with the above + EF-RF adapter, can report back on this. 💙

 

I am thinking about simply traveling with two teleconverters in the future and selling my Sigma 15mm Fisheye Lens to get a used Canon FE Zoom.

On 8/12/2024 at 2:36 AM, Adventurer said:

@DreiFish you are such a darling! Many thanks for putting the time + brain + energy in this.

 

I have one more question:

 

Will a 1.4x TC show some black vignetting on the Canon 8-15 Fisheye @ 8mm ?
 

Maybe somebody owning a canon fullframe body with the above + EF-RF adapter, can report back on this. 💙

 

I am thinking about simply traveling with two teleconverters in the future and selling my Sigma 15mm Fisheye Lens to get a used Canon FE Zoom.

Hey Adventurer,

 

No, the 8-15 + 1.4x (or 2x for that matter) doesn't vignette by itself. Of course, you need to have the right extensions for your dome port.. shorter extension may somewhat vignette, but that's a function of the port and extensions, not the lens and TC. 

 

The Canon FE Zoom is one of the best wide angle options on both Canon and Sony full frame systems. Also for their crop bodies. And it works great (with no TC or with a focal reducer) on M4/3 systems as well.

 

On 8/13/2024 at 7:20 PM, DreiFish said:

No, the 8-15 + 1.4x (or 2x for that matter) doesn't vignette by itself.

It doesn't? I was under impression that 8-15mm + 1.4x TC vignettes when set wider than 11mm, and only 2x TC gets you the full zoom range.

 

That's not vignetting -- you're just using it wider than intended, so you're part of the way towards the circular fisheye, just not all the way there. It's the exact same effect you would have if using it without a TC on full frame wider than 15mm...

 

10 hours ago, Barmaglot said:

It doesn't? I was under impression that 8-15mm + 1.4x TC vignettes when set wider than 11mm, and only 2x TC gets you the full zoom range.

That's splitting some very fine hairs. Vignetting refers to the effect itself, not to its cause. The question was "Will a 1.4x TC show some black vignetting on the Canon 8-15 Fisheye @ 8mm ?", and your answer to this, "No, the 8-15 + 1.4x (or 2x for that matter) doesn't vignette by itself." is quite misleading, as shooting the 8-15mm @ 8mm with 1.4x TC will produce significant "black vignetting", whereas using a 2x TC won't.

5 hours ago, Barmaglot said:

That's splitting some very fine hairs. Vignetting refers to the effect itself, not to its cause. The question was "Will a 1.4x TC show some black vignetting on the Canon 8-15 Fisheye @ 8mm ?", and your answer to this, "No, the 8-15 + 1.4x (or 2x for that matter) doesn't vignette by itself." is quite misleading, as shooting the 8-15mm @ 8mm with 1.4x TC will produce significant "black vignetting", whereas using a 2x TC won't.

This is the correct "dictionary" definition of vignetting.  Probably best to clarify the cause when referring to this phenomenon as you can't "fix" this type of vignetting which is caused by the limited image circle of the lens, while classic vignetting can be solved possibly by changing extensions or in some cases removing the dome shade.

My fault not beeing a native speaker.

 

@Barmaglot was right and by now I have both TC on my desk. Sadly I was put onto the wrong track by @DreiFish answer.

 

There is black edges in the frame when just using a 1.4x TC.

 

I could have remembered or computed it myself, though. 

does it mater if you use rectilinear or fisheye underwater? I vaguely remember reading that fisheye is better

I have a viltrox 9mm f2.8 e mount which is rectilinear and quite impressive, sharp, bright and with very good close focus- I am thinking of trying it in the red sea - am I likely to encounter any problems?

I'm using with my R5 the Canon RF 10-20 mm (rectilinear) and i'm really happy with it.

2 hours ago, Mike Saunders said:

does it mater if you use rectilinear or fisheye underwater? I vaguely remember reading that fisheye is better

I have a viltrox 9mm f2.8 e mount which is rectilinear and quite impressive, sharp, bright and with very good close focus- I am thinking of trying it in the red sea - am I likely to encounter any problems?

They have different looks and as, I assume, you are on some sort of cropped sensor system (9mm rectilinear) rectilinear is less problematic than on a FF sensor inme. Fisheyes have a more distorted (barrel) look and an extreme Field of View, up to 180 degrees coverage. It means you can come very close to big animals and frame large reef views with less water between the lens and your "subject". The ultrawide rectilinear lenses typically produce 100-110 degrees coverage and a "flatter" image. Still teally good for larger animals and reef views. Your frame will be filled from a little further away than the extreme fisheye (sometimes a good thing)--so more water in between lens and subject if it's something big. Inme the ulrawide rectilinear lenses, 14 mm on FF and wider, are very difficult to achieve good and even sharpness with. They need very large domes. This is different with cropped sensors, where just like the sensor, everything is smaller. I had acceptable results with a 10-20 zoom on Nikon DX.

180 degrees FoV with fisheye

10 mm rectilinear DX crop sensor, roughly 110 degrees FoV

Edited October 21Oct 21 by Christian K

On 6/19/2024 at 8:22 PM, DreiFish said:

Here are the results with the WWL-C (in air.. perhaps it's a bit more zoomed in in water?)

 

At the wide end (24mm on the base lens), Nauticam rates it as similar to a 10mm rectilinear lens, and it sorta is. Same horizontal field of view, but the rectilinear lens has a taller vertical field of view.

 

 

Zoomed all the way (50mm on the base lens), it closely matches the field of view of the 35mm rectilinear lens. This is despite Nauticam stating it should behave more like a 21mm lens. 

 

 

So I'd say it's a bit more versatile than the 14-35mm lens, if you can live with the barrel distortion.

This is great! Thanks for this. I did a similar comparison on my M43 set up between the OM 8mm fisheye with 4” acrylic dome and a 14-42 pancake with the AOI UWL-09 Pro glass wet lens. I didn’t have the foresight to photograph a wall for comparison. Nicely done. I will borrow your technique and repeat my tests. Thanks!

Edited October 22Oct 22 by ACHiPo

14 hours ago, Mike Saunders said:

does it mater if you use rectilinear or fisheye underwater? I vaguely remember reading that fisheye is better

I have a viltrox 9mm f2.8 e mount which is rectilinear and quite impressive, sharp, bright and with very good close focus- I am thinking of trying it in the red sea - am I likely to encounter any problems?

They both work but achieve different results. The fisheye has barrel distortion which has a distinctive look the center is bought forward big in the frame and the corners recede, so it draws attention to the subject. You just have to have a little care what is in the corners where larger objects distort - divers for example stretch out and look strange, so you have to place them in the frame properly and be aware from intrusions into the frame. They work quite well even in small domes.

Rectilinears on the other hand have narrower fields where straight lines stay straight everywhere. Usually this is only important for subjects that contain straight lines like interiors of wrecks, though of course there are other applications. Very wide rectilinears have perspective issues. something in the foreground that is much closer appears a lot larger, one example I have seen is a divers arm reaching forward, the hand looks way too big for the body it is attached to. You can take advantage of that of course but you need to be aware of it. The 10mm Laowa lens caused quite a stir, it performed quite well but interest seemed to wane and people complained about difficulties dealing with the perspective issues. with it. The other issues is corners can be softer, though the newer close focusing rectilinear lenses perform better in this regard, but still need larger domes than fisheyes.

thanks for the advice

I will be trying it with a nauticam 7inch dome on an alpha 6300 apsc. The dome is designed to be used with the sony 10-18 F4 so although not perfect I imagine it will be in the rough ballpark

Assume you have the lens and the dome? have you tried it out in the dome yet? I would suggest trying it before taking it UW as the 7" Nauticam has a fair bit of extension built in and the 9mm is a little shorter and has a wider angle of view than the 10-18mm. You can do this on land to see if it vignettes or not.

Golden rule: get as close as you possibly can. Then get a little closer. So depending on where and what you shoot, using the set-up that can give you as much FoV as possible suitable for the situation will generally (I’d dare to say always) yield better results. Water is one helluva degrading medium to photograph in.

130 degrees dFoV Nauticam WWLC

Edited October 23Oct 23 by Christian K