Dear all,

I use a Nauticam WWL1-B with an A7IV with the 28mm 2.0.
Up to now I slightly stopped the lens down to 3.5 to 5.6 and used the AF to focus on the diver. This worked quite well, in some pictures I still had some areas which were out of DOF.
Shooting with an ultrawide-angle lens lens above water I usually use a tripod, f 11 and focus only once at the beginning on something a few meters away to use the hyperfocal distance. Shut down AF and just shoot without using the AF again.
Up to now I didn't find something similar for the WWL1. Is it possible to do something similar (without tripod)?
Is there a formula to calculate the DOF for WWL1? Actually I only would like to have e.g. 1m to 10m or 3 to 30m sharp.

Best Jens 

Edited January 16, 20241 yr by airisfortires

AFAIK @Interceptor121 has the WWL 1b and might help. I am not aware of a specific calculator.

 

The DOF-calculators could work with the WACP and WWL as well as with other lenses. So you might grab the WWL1, Focus the camera lens on infinitiy and open the aperture as far as possible, put Camera in the housing with WWL-1, and take a photo over water of a measuring tape to see which is the furthest point that can be focussed on. 

Then use the DOF calculator to see what happens if you close the aperture.

 

 

On my GH5 I followed @Interceptor121 article and and I am more or less OK with the calculations.

 

https://interceptor121.com/2019/05/12/nauticam-wwl-1the-best-wide-angle-lens-for-underwater-video-on-the-gh5-and-other-micro-four-thirds/

 

I select a M43 camera from the list and I compile the form with a 11 mm lens trying different aperture and distances.

 

https://www.dofmaster.com/dofjs.html

 

 

 

One thing to consider is that DOF is not evenly distributed and you have 1/3 is in front of focus point and 2/3 behind more or less.  If you are a little short of depth of field focusing on something closer in the frame tends to make the best use of what you have.  The problem with DOF calculators is that you are focusing on a virtual image when underwater and if you were in a dome you could calculate the distances to the virtual image, I'm not sure that would work with the WWL. 

 

You should probably find that that using an 11mm lens should give about the right result in the calculator as it gets the magnification in the right ball park so the depth of field should be close to right.  This shows that focusing on something 1m away at f8 is sharp from 0.5m away from sensor to infinity.  The calculations show though that it is very sensitive to getting the focus distance right.  At f8 focusing at 0.95m gets 0.49m to 13.8 in focus.  focusing at 1.02m gets 0.5 to infinity in focus.  At F5.6 it is closer to focusing at 1.5m away to get 0.7m to infinity in focus.

So my take home message is, that i can use "classic" DOF calculators for "dry" lenses to (roughly) determine the DOF. Using a focal length of 11mm.
Thanks a lot!

Roughly is the key 😉

 

The magnification of those type of solution for depth of field purposes is not the stated 0.36x but more like 0.7x

to a fisheye 

In addition the dome means infinity point is reached closer

this means you cannot use distance calculations and focal length simply taking the lens stated magnification and distance 

In addition due to the expanded field of view the edges will be far far away and more more blurry 

from practical perspective all the small water contact optics are depending on the master lens and the edges just are ok at f/8 becoming better at f/11

at wider aperture the lens will be blurry regardless of depth of field because the lens itself is not sharp 

you can try focusing in a different point which is not your subject but closer and then see how this stays in focus

generally for most wide angle I dont use autofocus at all

I want to add if you look at my comparison of the 28 cs 28-60 you can see f/8 is the sweet spot for sharpness which is what I would use normally for photos 

for video where the edges are cropped you can go to f/5.6 but you need to set yourself to fixed focus as I described