Adventurer

Hi guys, the RETRA test mentioned is land based, correct? Same as the private beam shots by Dreifish in this forum. I would like to point out that any strobe that utilizes a dome (such as Seacam, Z330, Marelux) will give you a highly distorted impression of the real beam pattern that will be produced underwater. Once the dome glas is submerged in water it acts like a lens increasing the beam angle and evenly softens the output. -> The quality of light will improve underwater. Just keep that in mind when comparing land based shots.

That non-HD version has a horrible reputation of crushing your IQ to pieces. I would try to replace that with the new version or the Sony.

I think so too.

The likelihood is very high that my cameras and housings frequently see much more wet salt than yours. 😉 You are dead wrong about the mm thing. Prioritize correct NPP positioning and be amazed. You can lab / pool test this, which is the way to go, before you spend multiple thousand dollars with a dismal travel camera setup in your bag.

This is very nicely put 😁☝️ Cudos Klaus!

I am curious: was the optical performance on land acceptable for you with the 2.0 TC ? Then you might have sold it too quickly and it was just missing the optical punch by a good sized, well positioned dome underwater 🤔 My guess from the limited unvalidated data donoring in this forum is that you might need 85mm of extensions with the 1.4x TC and 140mm nauticam dome. The slightly larger 180mm Nauticam dome might yield much better results with the 1.4x or 2.0x in the game.

Hey @fruehaufsteher2 and @Architeuthis, very glad you chimed in on this and that you are interested so much in the materia. I‘ll try to put this as simple and practical as I can, being a non native speaker: I understood the situation with both of you, is that you abandoned WACP or FCP etc in search for better IQ. Manufacturer portlists (Marelux, Nauticam, Ikelite etc. ) target to a extension ring + dome combination that will give you maximum zoom range / flexibility on that Canon EF 8-15. Mainly because they might not want customers complaining that the dome sunshade or parts of the extension ring are in the picture, because it’s an obvious thing to complain about if you have no clue and just bought expensive glas 😁. The dilemma is that the dome is positioned to close to the lens to archive this flexibility. A fisheye sees „everything“ which is right in front of the entrance pupil (180 degrees diagonal or even circular). So you must use a full sphere dome. Bummer: none of the Nauticam domes is a real full sphere, like the large Matty Smith domes are… the 140mm dome is missing a tiny fraction in the end which causes a significant offset in the NPP position. This is very practical but does not help your hunt for maximum IQ. I measured and computed this for my 140mm Marelux Fisheye Dome and there you would need a 7.5mm Extension behind the dome for exakt positioning. Nauticam will be very similar to this I suppose. The 140mm dome with Nauticam/Marelux itself has a small tunnel section of another 7mm, so you can easily see how quickly 1.5cm unwanted offset sneak up on you. Bottom Line: So even the dome you thought which to be a full sphere for your fisheye is not. As you already own the Teleconverters (TCs) the logic step is to use them to shrink your field of view. Then you can use domes which are not full sphere, such as the medium sized 180mm dome, @RomiK used for some test shots in this forum. You can of course also do this with the 140mm dome if you already own it. Next Step: ditch flexibility and abandon the 8mm focal length end -> as a sacrifice for IQ the 15mm zoom end is the preferred operation mode for you. With TC 1.4x you get 21mm focal length. With TC 2.0x you get to 30mm focal length. Put your metabones adapter / sigma MC 11 plus the Teleconverter and lens on the camera and mount it inside the housing. Measure the distance from housing port flange to the red dot on the Canon EF 8-15mm sunshade. This is the minimum length of the extension ring you will need from Nauticam. I suppose even 7mm to 1cm more because of what I wrote above about the 140mm domes. You will loose some of the wide angle part of this fisheye zoom, as the lens sits now more deep inside the extension ring tunnel. But honestly, would you have used that portion very often underwater? I hope my best practice is comprehensive for you. If something is unclear just ask.

Putting a TC1.4x or TC2.0x in the system + getting a loooong port extension to use the 8-15 @ 15mm zoomed in -> 21mm / 30mm focal length with domes will give you better IQ and build the CFWA system you mention.

Chris, I think you are still not understanding. It's not just about perfect corners. The wrong way will introduce all sort of optical degradation including abberations etc.

Actually No. @RomiK My recommendation for you, after testing it all out. If you want the 180mm (non full sphere dome), add the 1.4x TC or the 2.0x TC Add more Extension than just the recommended 20mm for the 1.4x TC and ditch the wide zoom parts IQ/Vignette. Nauticam says the Radius of the 180mm dome is 110mm. So put a pen inside the glas and measue 11cm backwards. Buy the extension ring, that will get that radius on the red dot on the EF 8-15mm sunshade. Menu ready cooked! Voila, enjoy great IQ zoomed in and even make decent split shots. PS: just realized @Chris Ross you hi-jacked this thread and totally took it off-topic. Please look at the thread title and re-evaluate who is missing a point here. In fact it's easy to miss the Non Paralax Point (NPP) here 😉

OK. Small misunderstand here. Gotcha. The problem with that small dome being not a full sphere is that with correct position you will need to run approx 28mm FullFrame focal lens in it or tighter, to get near the optimum position. There is just a very small part in the center which will give you non-soft IQ. If you operate it on APS-C oder MFT cameras that's driving you towards that solution of your IQ problem. Also the 16:9 crop in video very often let's you use the center of that lens. All the above is not specific to the EF 8-15mm and also applies to other lenses. The get the FF image IQ you paid for on the superb EF 8-15, it's recommended to get at least the Marelux or Nauticam 140mm (almost) full sphere dome.

A well balanced review by Henley Spiers appeared on DPG comparing the Apollo III 2.0 against RETRA and oneUW https://www.divephotoguide.com/underwater-photography-special-features/article/first-impressions-marelux-apollo-iii-2-0-strobe/ Summarized,.. he's not too impressed by the Lumilink but emphasizes and compares the solid MTL feature the Marelux Apollo III 2.0 offers. This was also the initial assumption why I bought two of these strobes: meaning that a classic ring strobe is unable to compete with repetitive speeds of xenon based flash guns.

It feels as if @Alex_Mustard is really personally touched about the matter. Very heart-warming 🙂 I found the perspective from a celebrity in underwater photography and judge very interesting. I specifically refer to the part where he describes when a judge is approached by contest participants with the question: "How did you like my shot ?" and the honest reply should be "Sorry, I have never seen your image before you showed it to me." 😪

@Chris Ross it depresses me how you communicate here in public, obviously just for writing the 180 degree counter argument to what I contributed here. How should I have missed the point? Can we please leave personal grudge aside? I am obviously going to loose this against a person with moderator status who seems to own this forum. My point and remark was, that in the promotional write-up from the ikelite blog, there are nice images, yes. But the underwater photographer Steve Miller has obviously cropped and processed his shots. Just a few are still in 3:2 - so he may have cropped where the sharpness is splendid, to make the images look nice. A lot of the photos have also extremely darkened corners. It makes the images look interesting but gives full frame users no clue, how many pixels they have to throw away of each shot to get a sharp piece. And the curvature IS NOT 80mm behind the entrance pupil on the 8" ikelite dome. An extension of approx 43mm will get you to the NPP of the Canon EF 8-15 fisheye lens. As I have done some more chessfield testing in the bathtub yesterday, I can tell you that also the Fisheye is not invincible when it comes to dome abuse and mis-positioning. Have a read here:

Well with the frequency at which new products enter the market this year your current converter might already be outdated once it arrives from Taiwan with you and you are drooling at the next new strobe that just was announced. So online updating would be highly appreciated over importing and exporting physical goods which will easily eat up $100++ for one round trip shipment.

I am totally with you, Isaac. But as the original intention of this thread was to build an excel sheet that readers might take for granted I would suggest to abandon that mission. The case illustrates: You simply do not know how accurate your volunteering data donors are at measuring and reading the results.

Quite evil post @Barmaglot ?!?! Have you had bad experience with them or are you even affiliated with an INON competitor ? That you can pull off guide numbers beyond 40 out of compact 4xAA design has been successfully demonstrated by Canon EX Speedlites more than a decade ago. Canon 580EX II had GN = 58 Design has further progressed to shrink size and level up to GN60 in compact designs, this is @ 200mm focal length, with Canon Speedlite EL-1 though. But looking at the available water cooling and INONs advanced experience in underwater reflector design, crossing the GN40 barrier in year 2025 sounds quite archivable to me; even if you have to deliver a wider beam.

KickAss question 👌 - RETRA UWT shows that it should be possible to communicate with your underwater lighting product via Bluetooth in the 21st century. Turtle TRT at least delivers updates and configurations via USB connections and Apples App Store. Wireless Update Distribution would save us all from a lot of headaches a shipping cost frustration. 🙏

Friends told me which have seen the prototype on a trade show that INON is heading to be part of the beyond Guide Number 40 club with that strobe. In fact way beyond: aiming at the GN44 / GN45 region. All this while maintaining the 4x Eneloop design and small size and weight of a Z330 body. This would be very travel friendly and amazing advance in electronics efficiency. 😎 exiting times!

Well, a +4 diopter should not break the bank and also add less than 30 gramms to your travel weight. As long as you do plan on doing splits (over under shots) the diopter will make your lens AF much faster, as the virtual image never appears at infinity when the dome is dipped in water. It will pull the AF to a working area that is more likely to happen underwater. Having said that, you may also improve your RF 14-35 with a minor diopter when working behind more compact domes.

No, we certainly do not agree to this. I have not seen an an led torch which was able to out-compete strobes (even when they are in HSS mode). And I have seen and used 20.000 lumen video lights validated in an Ulbricht sphere.

Reviving these old findings, as I have done some Fisheye +1.4TC and +2.0TC tests today. Quint essence: if your NPP aligment is not 100% prudent you will struggle hard to get a decent thin water line. In fact you might constantly fail to get a decent over under split shot, just because of the NPP mispositioning. We previsouly concluded that if you go wider than 20mm focal length the pincussion distortion get's pretty annoying and is hard to deal with as most of us tend to tilt the camera up and down for their underwater compositions. Another thing to consider is the hyper-focal distance, to maximize sharpness of above water and below water scenes. On full frame sensors this will quickly force you to ditch diffraction concerns and set F22. On 20mm focal length you might even want more. In the Canon RF lineup there are actually not many wide angle lenses which will allow this. Most of them have F22 as a maximum. Basically you have two roads to go: add a TC 1.4x or 2.0x to the Canon EF 8-15mm Fisheye and enjoy beeing able to set your lens to 21mm focal + enjoy F32. OR stay native in the RF mount and enjoy 5.5 stops OIS + IBIS and an ultra light weight and affordable lens, the: Canon RF 15-30mm F4.5-6.3 IS STM which has also proven to be sharper behind domes than it's more heavy and pricy siblings from Canon's L line. The latter ones however will not allow you more than F22 -> so here comes the real charming fact about the grey STM wide angle zoom: it does F32 @ 30mm focal length. At the highly desired 20mm focal length it will give you F25. As I was also asked about the alignment tests with the charts above, I may have a more easy simplyfied wording for you all: If the stuff underwater looks bigger than what's on the surface, you lens is very likely to be positioned too close to the dome and you will need to buy more extension rings from your housing maker dealer. Very often these may be as many lenghty extensions as you can afford before you hit tunnel vision from the port system.

Well that does not match Phil's picture posted above. And while it makes sense, that diffent camera brands (Nikon Z, Sony E, Canon RF) have different flange to housing distances and therefore different port charts, it would not make too much sense, if Sony E Mount Camera Model X has different flange distance than model Y and Z. In that case camera X, Y and Z would need new different port charts. I think the source of 4mm gap: 43mm (measured by Phil) versus 39.1 (measured by @Isaac Szabo customer and confirmed by Marelux engineering) might have a more simple explanation. @Phil Rudin, could you be so kind and have a look if there is a blank space at the beginning of your ruler, that you have put onto the cameras flange? This is something we could not see in the two images provided.

Yes, the MFD of 30cm is too high. You will need a dome diameter of approx 52cm for it. What you can do as a solution is to put a +4 diopter on the lens to improve the focus on the virtual image. The lens entrance pupils sits approx 3.3cm too far inside the housing for optimal position of the entrance pupil behind the dome. Hydronalin in Germany has a solution for making affordable INON Glas domes work for that lens and the RF 35mm, if the +4 diopter does not do the job for you.

@Pavel Kolpakov as you are an expert on HSS as I have read here: https://wetpixel.com/articles/fundamentals-of-ttl-strobe-control-by-pavel-kolpakov/P3 Does this old statement from you, when there was mainly just the RETRA strobe supporting HSS, still hold: „For uniform illumination of the frame with such a shutter operation, the flash should be a long sequence of short flashes with a repetition rate of about 30 kilohertz, firing all the time while the open shutter slit moves along the window. The total burn time of these flashes is about five times longer than that of a mono-flash, while its intensity is noticeably lower. It is customary to regulate the power of the HSS flash by changing the frequency of these pulses.“ As you explicitly market „no HSS banding“ for your upcoming strobes. Were there strobes which showed this on some occasions? Do the current HSS capable strobes act differently? Meaning mainly: 1.) RETRA 2.) Marelux Apollo III 2.0 3.) Backscatter HF-1 Hybrid Strobe 4.) Marelux Apollo S Backscatter writes in their manual that in HSS mode the strobe power dial does not have any function and the HF-1 will fire HSS always in same strength. Contrary Marelux seems to allow adjustments in M-HSS mode. Does your 30 kHz and five times longer duration statement from 2021 still apply to the HSS strobes mentioned above and your upcoming strobe?