Canon FF lens lens lenses..

[Orestis Papadakis]

12 hours ago, Chris Ross said:

The point to remember is the field of view between rectilinear and fisheye is not the same the rendering is quite different between them as the fisheye uses barrel distortion to achieve a 180° diagonal field, something not possible in rectilinear lenses.    Also the diagonal field is a bit misleading for comparisons as well as fisheyes stretch more in the corner, if you want to compare coverage then using the horizontal field works better.  See this table below which lists field s of various focal lengths.

 

Full frame	horizontal	vertical	diagonal
15mm Fisheye	143	92	178
10mm Rect	122	100	130
14mm rect	104	81	114
16mm Rect	97	74	107
20mm Rect	84	62	94
24mm Rect	74	53	84

 

You can see the 10mm goes close and in fact the vertical field is larger than the fisheye,   However it needs a big dome port to provide good corners.

 

Another thing to remember is just because a lens performs well on land it doesn't always translate to good UW performance.  In particular a lens needs to focus very close to work well in a dome.  Your 24-105 lens for example has a minimum focus distance of 450mm but is measured to focus at 332mm at the wide end, so while it will work in the domes specified it won't let you get in close.  UW photography is all about getting in close to minimise the amount of water which degrades the image between you and the subject.  Which brings up another point in that just because you own a lens (or a camera for that matter) doesn't mean it's the best option to take UW. 

 

A big reason you want close focusing lenses is also because in dome ports you are actually trying to focus on a virtual image underwater, this is located 3 dome radii from the port surface , so quite close.  Some older lenses would not even achieve focus with a dome UW.  This link explains:  https://oceanity.com.au/articles/view/understanding-flat-port-and-dome-port-theory.

 

Another important point with fisheye lenses is their rendering UW, most will focus on the dome if required and because of the barrel distortion the centre portion of the frame is magnified compared to the edges - it looks fatter so is makes the chosen foreground subject stand out against the background.  UW there are very few straight lines unless you are in a wreck or you include the surface in the frame edges you don't notice the barrel distortion as a problem.  They also generally work well in smaller domes.

 

Rectilinear lenses have their places for wreck photos and also some scientific work, but they need usually big domes to work at their best, but this varies with the lens, very close focusing lenses seem to be able to use smaller domes in general.

 

 

 

This is invaluable information and food for a lot of study to come!

What I understand is that u/w behind domes, the barrel distortion of the fisheye is an ally, that I couldn't have imagined.

 

12 hours ago, Chris Ross said:

When using a tele converter with the 8-15 you need to use the TC in addition to the RF-EF converter not instead of.  The EF lenses won't achieve focus without the RF-EF converter which is basically just an extension tube.

 

Also if you are on Canon and don't think you will use the Spherical fisheye option you could consider using the SIgma 15mm fisheye instead, it's cheaper and many people are quite happy with it.

 

From a quick search, I am not sure I could even mount a teleconverter on an EF lens plus the EF to RF mount adapter. For the moment I am not too worried though, as I have tons of other information and equipment to study and understand!

 

11 hours ago, ChipBPhoto said:

Wow - I am impressed at all the amazing knowledge shared in this single discussion!  @Orestis Papadakis all I can say is welcome to the addiction!  And what a fun addiction uw photography is!

 

I am both a long-time Canon photog and now also have a Sony for uw work.  Your R6ii is an amazing body that will perform extremely well both underwater and above.  If I could share a couple points from my days asking the very same questions….

 

First, I too hated the fisheye look.  I do a lot of wreck photography.  With that said, a fisheye, even on a wreck with many straight lines, is actually a powerful tool to highlight your subject or even a particular part of the wreck.  As @TimG said, it just “works” in the underwater world.  On my first Canon I used a fisheye almost exclusively with great success.

 

Now step forward to 2020 when I bought my first full frame uw body….

 

It was then when I was introduced to a new world of Water Contact Lenses.  I had dreams of owning a big 230 dome so I could look like the other talented photogs on the boat and make those same quality images.  Nauticam, however, set an entirely new path of bringing a brand new way for our cameras to see much sharper, and at wider apertures.  They also wanted to make a non-remarkable lens such as a 24mm or 28mm into a wide angle dream with 130 degree field of view!  While not quite a 180 fisheye, 130 degrees was by far better than most out there, AND it would zoom as well.

 

The WACP was born!  It was a hit to all that used it.

 

…It was also quite expensive.  

 

Shortly after, they introduced the WWL series to be an even smaller, cheaper solution with similar results.  Basically, a WACP “lite” that the rest of us could afford.  Oh, and they can literally focus on a subject almost touching the dome!  
 

After learning all this in 2020, I reluctantly purchased a WWL with my 2020 system and it was literally all I could ever want!  I had full zoom in a wide field of view and sharp corners without having go to f/13 or above.  This meant I didn’t need to push my strobe power to the max and I could experiment with more shallow depth of field for more unique, professional looking images.  f/11 and quite often f/8 will yield acceptably sharp frames, even in the corners.  Canon has now introduced the very affordable RF 24-50 which works exceptionally well behind the Nauticam WWL-C.  
 

Remember I said I said almost always used a fisheye pre-2020?  That was before the WWL.  And the discussion of whether you should add a 1.4 teleconverter to the 8-15 now completely goes away.  With the WWL you have a wide lens AND a zoom for additional reach, all in the same port.  No need to decide before you dive; this one solution will do it all!

 

So does it completely replace my Canon 8-15?  Mostly, yes.  I still have the 8-15 with a 140 dome for ultra wide, clear water dives.  It has, however, become a specialty tool for specific circumstances with the WWL being my primary, or go-to lens.
 

Since you are just starting out, I highly encourage you to do some research into a WWL-C before you get too far down the path with large domes, extensions, etc.  

 

The entire lens, port, and WWL-C will most likely be much less cost than a larger dome, all with terrific sharpness.  Oh, and did I mention it is substantially smaller than a 230 dome?  Huge bonus if you travel or just don’t want to drag around big gear.  
 

As a side not, I own the RF 14-35 for landscape work.  It is terrific lens, but the RF 24-50 with the WWL will do the same underwater much easier and sharper. 
 

Is there a downside to the WWL series?  The only one is you cannot do split images (over-unders) with it.  For me, that was not an issue as I would rarely do them.  Size, cost, and sharpness were my drivers in my decision and the WWL hit them all.
 

Hope this helps without throwing too much confusion in the party. 😁 

 

 

 

I am very very happy that my ignorance has led to the sharing of such knowledge and information!!

As you can see, even without getting my equipment put together yet, the addiction has already got me...

In the years to come, after I gain some experience and perception, I hope I will be able to experiment with more advanced and complex housing, WWL, etc, but for the moment I'm struggling to even keep up with the terms, let alone understand their practicality and use.

 

So for now, I'll stick with the idea that I should get the 8-15mm and the 15-35mm, in order to give myself some time to deconstruct my decision... 😂

 

[Chris Ross]

21 minutes ago, Orestis Papadakis said:

 

From a quick search, I am not sure I could even mount a teleconverter on an EF lens plus the EF to RF mount adapter. For the moment I am not too worried though, as I have tons of other information and equipment to study and understand!

 

The Canon converters won't fit due to the extended nose, but people regularly use the Kenko 1.4x converters with the 8-15 zoom fisheyes.  Several housing makers provide zoom gears to use with the 8-15/1.4x combination.

[stillviking]

I would just add latest Canon RF 16mm 2.8 to discussion.

[Davide DB]

3 hours ago, stillviking said:

I would just add latest Canon RF 16mm 2.8 to discussion.

 

I understand your enthusiasm but we have a specific thread for this lens. Could we just use that? 🤪

[stillviking]

Sure! =D

 

Being on topic, I would ask about RF 24mm macro what would be minimum dome to work good on corners? I also never thought about this particular lens to underwater photography.