Who has followed my initial LX7 tests is aware of the few issues I have had at wide angle with the LX7.

One was the reflections back on the lens that I have now hopefully resolved using a black marker and changing the camera from white (and silver lens ring) to black and the other was flare.

Flare is an issue at wide angle even on land. What causes flare? Stray light coming from the sides that washes out the picture and eliminates contrast in the process.

Wide angle lens tend to have an ability to catch stray light from the sides and top and this is the reason why wet wide angle lenses have to be really coated well so that this effect is diminished, however it still can happen.

And it did happen to me with the Inon UWL-H100. The general advice to eliminate or reduce flare is to have a lens hood however lens hoods are generally not an option for wet lenses with an M67 thread mount. The only lens that I know that can position the hood on a screw mount is the fix UWL28M52 or UWL04 most of the other lens do not have a hood and have a circular lens unprotected from stray light. And this usually means at some point you will get flare.

So how do you get around it? In the case of the LX7 is pretty much a forced choice as the Inon UWL-H100 is the only lens that does not vignette at 28mm equivalent focal lenght so the possible solution is to put a hood on the lens.

Inon sells a hood for the UWL-H100 but the hood is attached through 6 allen bolts and its position can’t be fine tuned so to use the hood it is a requirement to change mount from M67 to the LD bayonet. You need also to convert the lens itself into an LD bayonet. If you go to your Inon dealer there is a relatively cheap service part that allows you to convert your M67 lens into a bayonet.

The LD bayonet is the latest incarnation of bayonet mount released by Inon. Whilst the old AD mount relied on a mechanical action to secure the lens, the new LD bayonet is much shallower and relies on a pin lock release to stay in place. There are two adapters on the market that are capable of attaching LD bayonet lenses to an M67 thread, one produced by Nauticam themselves and the other by the Japanese Fisheye Fix.

There is a  price difference between the adapters with the Fix being 20% more expensive.

The Nauticam adapter is the largest of the two. It has 6 allen bolts on the front and a thumb screw lock on the back to fix it in position. With LD lenses there is only one position to put the lens hood in the correct place so if for some reason the thread ends in the wrong place with your housing you will need to unscrew the front of the adapter to ensure the release lock is on the upper left of the port this happens the same way on the fix adapter. Make sure the little spring does not jump off in the process…Once the release lock is in the right area the fine tuning of the hood position is done with the thumb screw. A possible weakness is that if your housing port has no room for the thumb screw then this adapter is not good for you.

Whilst the Nauticam is made of plastic and metal the Fix seems to be 100% aluminum, this adapter looks better but does not have a mechanism to fix in place it relies on the strength of the M67 thread, however this locking system is compatible with any 67mm threaded port.

The fix allows to perfectly fine tune the hood position and it shows.

The alignment mechanism of the Nauticam adapter creates an alignment issue with the hood where the lens is few degrees turned clockwise.

With the fix this does not happen.

The hood can be properly aligned. Note that in both cases this does not mean more vignetting as the corners are not covered by the hood.

The other check I do is the position of the back of the lens, if there is a gap between the thread and the back of the lens this can create vignetting so it has to be as close as possible or even protruding as the Inon UWL-H100 mount type 2 does.

Let’s have a look at the back of those two adapters with teh UWL-H100 28LD attached.

The Nauticam thread is somewhat too long so the lens sits slightly more inside the thread line.

With the fix the situation changes sightly.

There seems to be little difference we will now check if there is an impact on the possible vignette in water.

As we can see there is a little bit of residual vignette on the bottom right corner when the lens is at 28mm equivalent focal length,

This is the same situation with the Fix

There is still a dark bottom right corner but it is less.

Inserting a 1.25mm spacer between the inner housing and the left side of the camera improves matters, this is because the lens of the LX7 is somewhat misaligned in the Nauticam housing and this corrects it.

With the spacer in the housing and the Nauticam adapter there is a tiny little residue of vignette but overall this is ok.

With the fix adapter this is the result.

No dark corners left.

So this is the recap:

1. You can change the UWL-H100 28M67 into an LD version with a cheap service part
2. Once the lens has an LD mount it is possible to attach the hood this will reduce flare
3. Vignetting is slightly increased but can be eliminated with a spacer with the Fix adapter
4. There is an issue of hood alignment an increased vignetting with the Nauticam LD adapter

A final note: inserting a spacer in the housing is risky, you need to know what you are doing as in theory the chance of flooding could increase so this is not for everyone.

My recommendation to those who want to improve contrast with the UWL-H100 is to convert to LD mount, attach the hood and get a Fisheye Fix LDF-M67 Pro adapter. Changing to bayonet has other advantages making lens swaps in water much faster and easier compared to the thread version especially with a lens as heavy as the UWL-H100.

There are few design issues and manufacturing errors in the Nauticam LD adapter that create issues with the LX7, most likely other cameras that are not so fussy will have no problems but if you have an LX7 avoid the Nauticam adapter entirely until a new production version is defined. I have given Nauticam the feedback and they will probably react.