with Macro and Super-Macro restrictors

This is an updated version of similar set I created last year. I decided to update and make it a bit more flexible, inspired partly by the Retra design.

https://makerworld.com/en/models/1746548-reduction-ring-set-for-backscatter-hf-1-strobe-v2#profileId-1856417

There is a primary reduction ring that does not block the light path but slightly limits spread of the wide-angle beam. I've found this useful for reducing flare and glow with very wide-angle lens (fisheye, etc) in less than crystal clear water. You can add additional restrictors with 60mm and 38mm apertures. These are useful for macro scenes and help to limit illumination of background features.

The rings are printed with PETG. There are three TPU rubber parts that hold the rings in place. The largest is a Bumper than can be placed on the HF-1 permanently and protects the strobe from bumps and scratches even when not using the reduction rings. I wish I'd done this when I first got the HF-1s as mine are pretty dinged up on the leading edge. Two smaller rubber gaskets are stretched over the macro rings and provide enough friction to hold the rings in place securely. Diffusors and Color filters can be used in combination with the set.

Here is a comparison of the effects of the reduction rings. Shot from a distance of about 1 meter with a 15mm FE lens:

As they are not decided on brands or models (cheaper end tho), i thought i'd ask here which brands/models people here have.

And also is there any special features/settings that needs to be found on the printer if printing things like extension rings (assuming this is more setting focused than zoom gears)?

As the prices for printers are getting lower, investing in one and printing 3 or so extension rings can offset the price already if buying privately (thanks @Dave_Hicks ).

I just posted a full Reduction Ring Set for the Backscatter Atom Strobe. I made this several months ago but didn't get around the sharing the design until now.

It uses some common parts shared between the reduction rings set for HF-1 and Retra ring sets I've designed. These work great and improve results for Macro/Super Macro work as well as Wide Angle in let the perfectly clear water.

https://makerworld.com/en/models/2766433-reduction-ring-set-for-backscatter-atom-strobe#profileId-3072067

Other Underwater Photography models can be found at:

https://makerworld.com/en/collections/16165730-uw-photography-by-dave-hicks

Given the huge amount of 3D printed projects on the net that often do not yield the desired results, we will add here only the working and tested projects.

Housings

• Nauticam NA-Z7 Housing Conversion for Nikon Z6/Z7 II

Plugs & Connectors

• Fibre Optic Cables? Make your own....

• Fiberglass Connector

• Fisheye Fix S100 Fiber optic connector attachment

• Connector for 3 mm inner diameter POF fiber optic cable

Floating Arms

• Float arm construction in 3D printing

Zoom and Focus Gears

• Adapter for Nauticam focus gears for the Canon 8-15mm and the Tokina 10-17mm fisheyes for use on MFT with 1x glassless adapter

• Nauticam Zoom Gear for Nikon 16-35mm lens (see also this post)

• Nauticam Zoom Gear for Nikon 24-50mm Z lens (see also this post)

• Nauticam Zoom Gear for Panasonic Lumix G Vario 14-42mm f/3.5-5.6 II ASPH Mega O.I.S.

• Canon 8-15 on Nauticam OM-1 Zoom gear using housing control

• Nauticam Zoom Gear for the Sony 28-60 in a Nauticam N100 housing

• Nauticam Focus Gear for Nikon 60mm 2.8G Macro Lens

• Nauticam Focus Gear for TTArtisan 100mm Z-mount

• Zoomgear for Nauticam Sony Housing for Tamron 17-28 and Sony 16-35 f4 1st Generation

• Salted line, Tokina 10-17mm zoom gear

• N85 focus gear for a Sigma 10-18mm zoom

• Nauticam Zoom gear for Nikon 8-15mm with 1.4 Teleconverter

• Nauticam Zoom gear for Nikon 14-24mm Z-mount

• Nauticam Zoom gear for Canon 8-15 Zoom Gear with MC-11

Strobes

• Snoot for Inon Z330 (small version)

• Snoot with a diaphragm for a Retra flash

• Diffuser for Inon Z330 strobe

• Backscatter MF-1 and MF-2 strobe power knob modification

• Modular Bumper and Macro Reduction Ring system for Backscatter HF-1 strobes

• Backscatter Optical Snoot 1 on a Sea and Sea YS-D3 strobe Adapter

• Reduction Ring Set for Retra Strobes w/Macro Rings

• Bumper Rings for Retra Strobes

• Backscatter Miniflash 2 (MF-2) and Snoot (OS-1) holder

• Retra Maxi Custom Knobs

• Backscatter MiniFlash Strobe - Gridfinity Tray

Tripods

• flexitray adaptor with integrated Swiss arca plate

Caps

• Nauticam N120 Housing Male Cap

• Nauticam N120 Port Female Cap

• Nauticam N85 Port Female Cap

• 67mm Cap with a Nauticam Logo

• Nauticam N100 Port Female Cover (Rear Port Cap)

• Semi Hard Port Cover for Nauticam 180mm Dome

• Nauticam WWL-1 lens back cap

• Hood and cap for Nauticam MFO-1, SMC and CMC lenses

• Port front cover for Ports with Nauticam Bajonet Mount (Version I & II)

• Front-Cover for MFO-1

• Nauticam SMC-1 SMC-2 SMC-3 Cover

• Rear-Cover for Nauticam Bajonet

• Protective ring for the Nauticam MFO-3

Other Parts

• NP-F Battery Holder

• Holder for Nauticam Hand Pump for Vacuum Valve

• Action Cam Mount for Long Clamp Carbonarm

• 1" Ball Mount for Suunto EON Core - Dive Computer

• Keldan 4 battery case

• Keldan 8 battery case

• KELDAN 8XR and 4XR protective Cover

• Scuba Emergency Shears Camera Arm Mount

• Camera arm mount for Venture Heated Vest Controller

• Transport Case for 16 AA Batteries

• Battery Case - 2x NITECORE NL2160HP

• M82 Lite Holder For MFO-3

• Nauticam hand vacuum pump tip

Any suggestions on how to clean them, or are they permanent?

Thank you,
Vitaly

Convert your OS-1 Miniflash snoot to work with your Atom Strobe

https://makerworld.com/en/models/2718050-snoot-adapter-os-1-to-atom-strobe#profileId-3010574

I have had the Backscatter Miniflash MF-1 and MF-2 strobes for many years and love the OS-1 Snoot that this small strobe was designed around. It's probably the best snoot on the market, accurate and easy to use. The new Atom strobe is more powerful than the Miniflash models, but not much bigger. It's pretty much replaced my MF-2 strobe.

But I really didn't want to buy the new OS-2 snoot for it. It turns out that the new model uses the same exacted optics and lens module as the older OS-1 snoot. It just uses a new mounting part to attach to the strobe. I have designed an adapter with very similar dimensions as the OS-2 snoot, and it works perfectly. The light cards from the OS-1 will also work in the updated snoot. 

Directions:

Remove the four M3 screws that hold the aluminum optics front end module from the OS-1 snoot. You will need a 2.5mm allen key wrench. 

Use four M3 20mm screws to attach the adapter to the OS-1 optics module. Do not over tighten, just slightly finger tight. Do NOT use a screw longer than 20mm or you will very likely crack the glass in the optics module. 

Filament Choice:

I strongly suggest using the recommended PETG for this model. PLA might work in the short term, but PLA does not wear well in the water and sun.  It might break unexpectedly when exposed to the elements. 

Atom

HF-1

Retra

Miniflash

https://makerworld.com/@awkward_swine/collections/16165730?appSharePlatform=copy

Since I don’t have a 3D printer (or the CAD skills to design a custom cap), I decided to improvise. With a little help from Google Gemini, this is what I came up with.

The cover is made from a 70 mm vinyl end cap, trimmed down so the depth matches the CMC‑2. Inside, I wove bungee to create four small “tabs” that snap under the top ledge of the lens body. That gives the cap a positive grip instead of relying on friction alone. I also added a parking loop on the hinge—just an extra layer of security in case the cover pops off before I have a chance to clip it to a D‑ring at the start of the dive.

Any thoughts or suggestions for improvement are welcome.

https://makerworld.com/en/models/2728055-n120-port-body-extensions-for-nauticam#profileId-3023087

NOTE: This is a technical print with a mission critical application. Failing to follow all of the suggested settings could result in a non-viable part.

There are many accessories for Nauticam Underwater Housings. One of the most essential are Port Body Extensions that are used to configure the length and offset of Macro and Dome ports to work with specific lenses. At some point I needed multiple copies of several ports extensions to support a growing family of lenses. Rather than buying more extensions, I decided to take on the engineering challenge of 3D printing a fully watertight, pressure resistant version of the parts.

The result is a full set of n120 port extensions for Nauticam housings. Others and I have made many dives to well over 100 feet / 30 meters with several of these printed port extensions. Every dive with the printed port extensions were 100% successful with no leaks or loss of vacuum. Just as good as the real thing. The one difference from the OEM part is that they don't have a locking mechanism. However, as they fit very snuggly after being rotated into position they are not going to come off. If under a vacuum or under the pressure of submersion, it would be nearly impossible for them to come off.

While I have not tested much beyond about 30 meters, I have confidence that these parts are strong enough to go much deeper. In the interest of caution, I suggest not diving beyond about 40 meters with these parts. If I am able to conduct tests to greater depths, I will update this suggestion.

NOTE: Just as with OEM ports, I recommend having a strap wrench available to help remove port extensions if you have trouble doing it by hand. If port extensions are left installed for an extended period, the lubrication will dry and it may be very hard to rotate the port off. For better leverage, keep the port extension locked to the housing and rotate the port off. Use the strap wrench if you need more leverage and grip. Rubber gloves also help with grip.

Print Plates with the most common extension sizes are included:

1.                  20mm

2.                  30mm

3.                  35mm

4.                  40mm

5.                  50mm

6.                  70mm

If you need a size not included, let me know and I can easily generate a new one from the Parametric CAD model.

Before diving a housing and camera using these port extensions I strongly suggest first:

·                Test the seal with an empty housing on the bench using the vacuum circuit for 24 hours.

·                Perform a test dive with an empty housing to gain confidence in the seal and strength of the printed part.

Print Preparation:

To get the strongest and most successful part possible, it is recommend to use a printer with a heated chamber and two print nozzles. The support material will be stronger and cleaner with a second nozzle. Using a single nozzle can weaken the part. The H2D, H2C, and X2D all meet this criteria in April 2026. Printing ASA or ABS without a 65C heated chamber will result is weaker layer bonds. You want this part to be as strong as possible. I have also created versions of this part with PETG, but not tested this material in the water. If you choose to attempt PETG, the settings for filament and slicer listed below should be largely the same. (substitute nozzle temps 5C higher than the default for PETG rather than the ASA values suggested)

After printing, carefully remove all of the support material. Be careful not to scratch or dent the sealing surfaces in particular. These are o-ring groove, and the inner surface at the top of the ring. The sealing surfaces should be filed and sanded using medium grit 400 and fine grit 1200 sandpaper. After sanding wash the part with soap and water using a toothbrush. Repeat sanding if necessary after inspection.

Install a Nauticam original o-ring in the printed port extension. Apply a light sheen of white PTFE lubricant such as Nauticam provides. (Tribolube, Cristolube) Do not use Silicone lube on these silicone orings as this can cause the orings to swell and leak.

Vacuum test the printed port body extension and o-ring in your Nauticam housing for at least 24 hours before attempting to use it underwater. If the vacuum circuit changes from Green to Flashing Yellow or Red, you have a bad seal. More sanding or a full reprint may be required.

Note: if the vacuum circuit light is Solid Yellow or Red, that indicates a weak battery in the circuit. Install a fresh battery and retest for 24 hours.

Print Profile Settings:

Filament Settings:

·                Bambulabs ASA dried for 12 hours

·                Flow Ratio: 1.1

·                Shrinkage 99.5

·                Retraction .55mm

·                Nozzle Temp: 270 / 275C

·                Bambulabs Support for ASA dried for 12 hours

Slicer Settings:

·                .4mm nozzle

·                .1mm layer height

·                10 wall perimeters

·                .5mm outer wall, inner wall, top surface

·                1.5 bridge flow

·                Concentric top / bottom surface pattern

·                2mm top / bottom shell thickness

·                100% infill (with 10 wall there should be NO infill)

·                150mm/s outer and inner wall speed

·                100mm/s top surface speed

·                25mm/s bridge speed

·                Enable Support ON

·                Tree(auto) support in Tree Organic Style

·                On build plate only ON

·                Remove small overhangs ON

·                Support base DEFAULT

·                Support interface SupABS

·                Top Z distance 0

Optical Sync Cable Port for Nauticam Housings

These plastic caps for the optical ports of your Nauticam Underwater Housing are one of the most lost and misplaced items in all of underwater photography! 

This design is a perfect replacement or spare part to carry with you on scuba diving expeditions. It fits any standard 7mm connector on underwater sync cables. It features a print in place rotating turret just like the OEM original part. 

Print these connectors in PETG for best results in underwater and outdoor environments. PLA may work initially but will likely swell, crack, or otherwise fail eventually. 

Print with PETG enabling supports and specify PLA support interface so the turret part breaks free successfully. After removing the tree supports from the center, use a long thin pick to remove the PLA support interface ring.  An outer brim may help to ensure a successful print. 

 https://makerworld.com/en/models/2726041-optical-sync-cable-port-for-nauticam-housings#profileId-3020623

If you want to make your own Sync Cables, see my other model for sync connectors and details to source multi-core fiber. 

https://makerworld.com/en/models/846729-diy-optical-fiber-sync-cable-connectors#profileId-1454437

I have been working on water-tight, pressure-proof 3D prints for a while now. I've been using some Port Floats for well over a year now that are still in perfect shape without a failure up to 100ft/30m across over one hundred dives.

I recently bought an old Olympus Zen glass dome port that should provide some perfect glass for a Curved 60mm Macro Port. I want to make a port body to receive the glass for that project. I figured a good stepping-stone along that path would be to first make a Port Body Extension Ring. Afterall, it is just a port that opens on both ends. :)

I made a rough draft design last week and iterated 5 or 6 prints tweaking the design and precise dimensions to get a perfect fit. I experimented with different materials as well, trying PETG, ABS, and finally ASA. The PETG prints came out fairly good, but I find that my printers just do a better, cleaner job with ABS or ASA. Smoother, cleaner, less stringing. ABS and ASA are also lighter weight and stronger in most ways than PETG along with better temperature resistance in hot environments. The final ASA protype print that I made was the cleanest off the print plate of all the iterations. I am using the same printing parameters that worked for watertight port floats, but these are much thicker and stronger.

Testing:

I have only tested the 3D printed port extensions by pulling a vacuum in the housing. No leaks after 24 hours. The next step is to test under pressure. Lacking any sort of pressure testing apparatus, I will probably just dive it to 30 meters in my old D850 housing with no camera installed.

Any suggestions on how or where to "Safely" pressure test a housing locally in Seattle would be welcome.

Ideally, I would want this to work to at least 50 or 60 meters so provide a safety margin. For reference, Nauticam advertises 100-150 meters. The port bodies are 12-14mm thick. My port floats have not failed at 30meters and they are only 2mm thick. CoPilot AI seems to think it should be good to about 17bar or 173 meters.

I decided to make 20mm and 40mm extensions to start with. My CAD design is parametric, so I can just plug in any value from about 15mm on up to create the model. I have not tweaked the design for n100 size ports, but that should be straightforward if I pursue that option.

I have several lens combos that need extension:

• 20mm:

  • 60mm macro port + 20mm for the Nikon 105Z lens

  • 140mm dome port + 20mm for the Nikon 8-15mm fisheye lens

• 40mm:

  • 140mm dome port + 20mm + 20mm extension for the Nikon 8-15mm + 1.4 teleconverter

• 70mm:

  • 8.5" dome port + 70mm for the Nikon 16-35mm lens

I use the 105mm and 8-15mm fisheye all the time. I bought a second 20mm extension so I can shoot both conveniently. However, I need to swap them around all the time if I want to shoot both the 105 and 8-15+TC in the same time frame. A 40mm port body dedicated to the 1.4TC setup would be a terrific addition to my collection.

A quick note on pricing of various options:

Saving money is NOT the goal here, it is much more about the satisfaction of building something myself. And building something that is unique and otherwise not for sale anywhere, like a custom Curved Macro Port. But it is interesting just to show what is possible.

• Printing with ASA costs about $2 USD in filament and 20-30 minutes of post processing labor, sanding, etc.

• Nauticam sells a 20mm extension for $390, 40mm for $430 USD.

• A rough quote from PCBWay is $165+shipping for an anodized aluminum CNC manufactured 40mm part based on my design.

• Sunk cost: Bambu P1S 3D printer sells for $399. One roll of ABS filament is $20 and enough to make ~10 port bodies.

• Labor cost for a retired engineer pursuing a passion project: $0/hour

Here are few images of the port bodies:

20mm and 40mm: PETG, ABS, ASA.

A Nauticam 20mm is over 200g. My ABS 20mm is 95g, the 40mm is 150g.

40mm ASA with Nauticam 70mm

40mm port body with 170mm dome port - Vacuum testing with Nauticam housing

What do folks think of this design? I've not tested it in the water yet but will soon.

Nauticam 140mm and 6-inch dome: (the smaller part in the photos is incomplete...)

Bracket and Clamp to store your OS-2 Snoot with the Backscatter Atom Strobe

A snoot is a fantastic way to make creative macro shots with underwater photography. The Backscatter Atom strobe is one of the best strobes on the market for macro photography and tailor made to use a snoot. The OS-2 snoot accessory for the Atom strobe is very easy to use, add, or remove underwater. But where do you store it when not actively using it during a dive? 

A short tether with a mini-bolt snap can secure it to your camera or BCD, but it dangles and might get in your way. A cleaner alternative is to make and use this bespoke caddy system to attach it securely to the strobe itself. It's easy to add or remove as needed, and strong enough that it's not going to fall off. (I still recommend also using a short tether and mini-bolt snap to clip off to a zip-tied o-ring on the ball mount, as seen in the photo)

This design will provide a simple and secure attachment bracket and clap to mount your OS-2 strobe. It's made of several parts:

• TPU rubber friction ring with key-bumps to align the ring. Slips over the ridges just in front of the optical port. This part can be left in place permanently and may provide some bump protection when the bracket is not installed.

• PETG bracket with inner grooves to align with the TPU ring. Reversable so the clamp can be place on the left or right side of the ball mount. It is secured with an M3x6mm screw and nut. 

• PETG clamp that slips over the mounting point on the bracket. Can be with fixed to the bracket with either the Hinge-Clip or a pair of M3x12 screws and nuts. 

• (Optional) Print in place Hinge-Clip. Using the Hinge-Clip makes is possible to remove the clamp without tools or loosing your screws and nuts between dives. This print in place hinge replaces the M3x12mm screws to mount the clamp that actually holds the snoot. The printed hinge-clip is very secure, but actual M3 screws and nuts are even more solid. Just less convenient if you wish the dive without the snoot or the clamp sticking out. The white dot on the Top Surface of the hinge needs to be aligned toward the body of the strobe to fit correctly. 

Filament Choice:

I strongly suggest using the recommended TPU and PETG combination. Don't use PLA. It might work in the short term, but PLA does not wear well in the water and sun. It can also be too stiff and brittle to work well for this design. It might also break unexpectedly when exposed to the elements. 

• The rubber friction ring must be some type of elastic TPU to slip over the strobe itself.

• The clamp, bracket, and hinge parts that actually hold the Snoot need to be flexible and resilient to bending over time. PETG is a good material for this purpose. ABS might work but could be too stiff.

The print in place hinge-clamp might need a little encouragement to break free and allow movement. Just work it gentle and slowly to snap any minor adhesion

Download from Makerworld:

https://makerworld.com/en/models/2564103-backscatter-atom-strobe-caddy-for-os-2-snoot#profileId-2825583

for some reason I happen to own an old Nikonos III + 15mm underwater lens which I got more than 10 years ago on ebay.

It's been a beloved pet project for me to dive this lens again on a full frame DSLM camera such as my R6 Mark II.

Mainly because of IQ and the very compact size.

I am aware that it's not a fisheye and equivalent to a 20mm lens, my favourite wide angle range underwater.

There are two versions.

The earlier one only fits on Nikonos I, ii and iii since it blocks the TTL-sensor of the Nikonos IV and V.
The earlier lens is told to be the better performer due to its retro focusing design.

This makes it even more mouthwatering after reading this optical benchmark done by Pawel Achtel from 2014 :

https://wetpixel.com/articles/test-optical-performance-of-nikonos-15mm-flat-and-dome-ports

It resulted in some cinema products: https://achtel.com/3deep/

I am also aware of this tinkering thread by @ianmarsh ( thank you Ian ! )
https://waterpixels.net/forums/topic/418-nikonos-15mm-service-manuals-and-schematics-was-do-15s-need-servicing/

I have some questions though, matching with my previous experience.

In the Nauticam Sony NEX-5 days and Nikonos NEX Adapter, the Version III would not mount on the crop camera as it's derriere would have hit the image sensor.

You needed to get a Nikonos 15mm in the V (five not three) version to make it work. I never did 🙃
If I remember correctly this was the reason why the III Version of the Nikon Nikonos UW-Nikkor 15mm f/2.8 would not mount on APS-C type.

Now will full frame and mirrorless I see that Nauticam has a Nikonos-Full-Frame Adapter in their portfolio, but it's just for the A7 Sony camera series, not for Canon.
https://www.nauticam.com/products/nikonos-adaptor-for-na-a7

In another thread together with @Phil Rudin and @Isaac Szabo that I recall but did not find we learned that Nauticam has different bayonet to camera flange distances between their brand housings.

Some SONY models seem to sit closer to the Nauticam Bayonet, especially closer than the Canon DSLMs.

Nauticams Nikonos Adapter for full frame just seems to work for A7/A7R/A7S System - anybody around using it with a 15mm lens and can report about the experience?

In my MARELUX the Canon R6 II sits even deeper inside the housing, which may provoke a collision with the two knobs for focus and aperture control.

I have exactly this set including the viewfinder: https://www.pacificrimcamera.com/rl/01394/01394.pdf

Seeking your advice and comment in hope to make my pet project come alive.

• nothing to hold it when not on the lense

• Heavy (relatively ;) )

• Black... I don't like ... seriously difficult to find if it his lost.

I build a new one, to print with TPU

l

You can print it in red ( like I made it) or black and why not pink or some phosphorecent TPU....

If you want the 3D STL... ask I will sent you the file.
If you want some modification same ask...

Does anyone have proven plans to 3D print a Nauticam C815-Z+1.4 zoom gear?

Note - this is the for the Canon 8-15 AND the 1.4 TC, not the standard 8-15 gear.

Thanks in advance!

chip
 

I have a very nice AOI UCL-05 LF +6 diopter (the old model), which I use a lot as it's way sharper than the Inon UCL-165 I used before.

However, some faint traces have appeared, and seem to be inside the unit. I first noticed them underwater.
I'm guessing this means something is failing, maybe the retaining ring?

Can anything be done in this situation? It's an old model, and I'm now in Japan so sending it back to a dealer seems to be difficult.

Thanks!

Ben

I planned on designing and 3d printing one.

The simplest design seems to be a funnel style snoot, but are there disadvantages to this design?

Also what type of material would you print it out of? PETG seems to be the favourite, but would something more matte like CF-PETG or Nylon be a better choice?

I was using them for approx. 2 years, never flooded them and cannot remember that I ever dropped a single drop of (salt)water into the battery compartment. I fear that this problem will come again and plan to put together some kind of "emergency kit" that I can use when I am abroad.

The strobes had the electrodes replaced at Backscatter (kind, quick and labour as a goodwill case), are now on their way back and I asked Sevag (the Service Manager), what components he would suggest for such a kit. I think his suggestion may be of interest also for others here:

"...The best tools to have with you are some alcohol wipes, liquid isopropyl alcohol if possible (90-99% is best), a brush to help reach the contacts at the base of the strobe, and a fiberglass cleaning tool like one of these: https://www.backscatter.com/Hama-Contact-Cleaner-CAUTION-Fiberglass ..."

What is the opinion of UW- photographers, who have had problems in the past with strobe electrodes, about such a "kit"? How did you deal with corroded electrodes? Any additional suggestions?

Thanks for the input, Wolfgang

So as I was tired of the situation I planned to do on myself new battery packs that I can control the cells individually in a normal charger. Then I noticed than the original battery packs are simple as two 18650 cells connected in series, so they give 7,4 volts (nominal). So I decided that if I am going to do it I want to not charge batteies in a day during a trip, tipically 4 dives. So I made my packs with two packs of two 18650 batteries connectd in parallel, so I double de mah. resulting in this packs you can see in the pictures.

I made the design and went to a turner to make the pack with the threads and the o'ring channels, I bought the cables with the conector already welded from Subtronic and I bougt the battery holders from Aliexpress, sended the alluminum pack to anodize and I got the cable penetrators from BlueRov  which i had to modificate a little bit in order to hold 6.5 mm cable. 

It's been a bit expensive, around 300 euros each plus my time and my job, but I can control every cell one by one, but everytime I go to the water I am absolutely sure they are perfectly charged, if any of the cells it's damaged i can change it for a ridicculous price comparing with a wole pack, and I can do on myself in seconds. The contra is that this battery packs are big. So now I am planning to make another packs with only to cells in serial connection, ir order to make it thinner, to use it when at home and tipically dive once or two a week.

The connector is an S4, so if Seacam uses the same voltage this would also work with them