Adventurer

Maybe I should clarify that I have had access to the above products and measured them with a caliper to verify the brand statements. Thanks to my diving friends, eBay and dive expos. Marelux, Nauticam and ZEN seem to buy the exact same BK7 Glas spheres for their large 230mm dome and small (almost full sphere) 140mm diameter domes. Marelux and Nauticam 180mm dome are very similar. The large Marelux Dome is more full sphere (fisheye capable) than the ZEN or Nauticam 230mm and the only one which I was not able to personally touch / buy / measure yet. Marelux has improved coatings and their dome and luxury pelicase like packaging for their biggest dome. ZEN titles their 230mm and 170mm diameter fisheye domes, which is just a very bad marketing gag, as both are not full spheres, which you would expect from a product carrying the word “fisheye” in it. The most affordable fisheye dome with Nauticam and MARELUX is their 140mm diameter product. It’s (almost) full sphere. If you get in dialog with them they will tell you it’s not full sphere, but they are a little over-precise here. The roundness goes up to something like 169deg to 178deg before their glas enters the mounting frame. So it’s fine and usable with 180deg circular and diagonal fisheyes. For both r = 65-70mm depending how precise you measure. officially published is r=69mm for these two. It’s worth noting that the measurement error extrapolates with the aromatic, so I had come up with an approximation of just r = 61mm inner measurement in the past.

I disagree. You can have the same rear conic domeport design, you mentioned, with MARELUX medium sized dome. Also Marelux offers similar and even improved dome options versus Nauticam. SEACAM has excellent dome options as well and INON is the most affordable high quality coated glass dome options in the market. The inner extension ring and port hole diameter is widest with MARELUX, offering a better angle of view, often without needing a conic rear shape for mirrorless full frame cameras. INON’s port hole and Ikelite are a little more narrow and INON’s dome ports are small but have a very large radius, compared to their size. For this particular Canon lens INONs Dome Port II might just work well. It has inner sphere r=75mm + 4mm glas.

Naughtycam, naughty scam… Why do you act like a brand ambassador further enforcing this unholy monopoly and hi-jack this thread in such a bad manor? It makes absolutely no sense to use a third party manufacturers dome for another housing brand. Also I do not see why that particular dome should be “the best”.

I have just made a land test and can confirm that the AI SERVO autofocus will always work properly on stuff that’s just 20cm from sensor plane at any aperture set. This is surprising and contrary to its published specs, saying 28cm If you crank up the aperture to F11 on R6 Mark II the DOF creeps even one centimeter more towards the lens. So everything more distant than 19cm from sensor plane is sharp. This lens is definitely a keeper! That was practically measured with a ruler that is approx 9cm from entrance pupil. The entrance pupil (npp) is quite easy to locate and easy to remember as it just little offside the focus control ring, meaning right at the end of the non-moving part of the lens during zooming. hello 9cm radius domes and above! here I come.

The way I understood this is as follows: The Focus is Drive-by-Wire on that lens. Canon just does not want to waste AutoFocus algorithm on that rare focus portion with the macro magnification, so that is why they force you to use the MF to get there. But all the optical & mechanical parts in that lens technically allow you to go as close as 12,8cm. So I assume they just limited the AF range and you will not re-arrange all optical elements when activating the macro focusing distance. Just a humble assumption. So if you focus at 28cm (on land) with a lens does not have this feature and MFD=28cm everything closer to sensor plane than 28cm will be blurry. Contrary to the above if I auto-focus at 28cm with that particular Canon 15-30mm at F16, things as close as 18cm will also be sharp.

I would like to take Massimo’s instructive article and apply it to two slightly unusual underwater contact optics to better understand what’s going on and maybe derive a practical application. Have a look at the two for 60mm full frame focal length designed: Nauticam MWL-1 and Kraken / Weefine WFL-09s Both lenses claim interesting 150deg FOV @ 60mm focal length when used in optimum. For Nauticam I am unable to find the lens factor but Weefine published 0.32x magnification. So we can assume the factors are similar. Nauticam recommends to shoot their lens at least at F16 aperture for good sharpness. The Nauticam lens has 7 Elements in 5 groups and the Weefine/Kraken 7 Elements in 6 groups. So both factories take on the problem looks very similar. According to Interceptor this means that an on object in one meter distance will appear at 3,13m when viewed through the lens underwater. You can apply classical topside depth of field calculator to a 60mm lens @ F16 and learn that softness of that lens reported might be solely blamed to a DOF issue. There is also one Wetpixel Review by Jack Connick and one on divephotoguide by Mathew Sullivan, where both authors report that you have to significantly stop down to F29 or F32 if you use this lens with a 100mm or 105mm macro. Especially the images by Mathew exhibit shallow DOF in wide angle shots, I think. Some underwater photographers might have mistaken these shallow DOF with missing corner sharpness on dome ports, I think, and did not consider these lenses as an improvement. I however see these two as highly underestimated because they bring flexibility to your dive and highly optimize remote travel size and weight. The downer is however that not many mirrorless Systems have native 60mm Macro lenses. Nikonians being in the supreme position, followed by Micro4thirds Users which have a 30mm Macro turning into 60mm FF equivalent. Sony FF Users need a Nikon adapter and Canon Users would need to twist an EF-S 60mm macro and live with slight vigneting on FF if used on the wrong focusing distance and aperture. So,… what does this give of any use to us? Well.. how about if we utilize classical topside DOF calculators and look at hyperfocal distances and apertures. What we then can learn from these, is that we simply have to use these lenses at higher working distances. Sadly though both lenses were marketed heavily with the claim that you can focus right on the front element. The point where you would suffer most from shallow DOF issues. When shooting these two lenses with more subject distance and your strobes brought forward towards the subject you will buy back lens sharpness. examples: The recommended Nauticam example at F16 on a full frame 60mm lens renders as follows: Hyperfocal distance focussin point on Land = 7.55 m underwater Equivalent 0.32x HF AF distance = 2.42 m On Land everything sharp from 3,77m to Infinty UW (0.32x) sharp from approx 1.2m Changing these to a 100mm lens this significantly drops: The NOT recommended example at F16 on a full frame 100mm lens renders as follows: Hyperfocal distance focusing point on Land = 20.9 m underwater Equivalent 0.32x HF AF distance = 6.7 m On Land everything sharp from 10.45 m to Infinty UW (0.32x) sharp from approx 3.35 m Having worked through the above these lens-rapers go heavily against the average underwater photographers intuition and could make a small exception of the steadily heard “get close”.

Still trying to get my brain around what you wrote above. Looking at your previous blog post I thought the driving force behind the required dome size was the MOD (MFD). Assuming MinimumFocussingDistance (MFD) at 15mm I calculated the following two scenarios: Always using (I-P)= 97.69mm MFD = 128mm @ 15 mm focal length: MFD-(I-P)= 128-97.69 = 30.31mm minimum Radius of the Dome, and required Dome Glas Diameter just D=61mm MFD = 280mm @ 15 mm focal length: MFD-(I-P)= 280-97.69 = 182.31mm minimum Radius of the Dome, and required Dome Glas Diameter D=364mm Could somebody please verify my above math? —- If my calculation is correct, how do you derive the 230mm dome from a 15mm lens? I have to point out that there are various domes in 230mm size on the market having different port diameters and some have conic or flat extensions behind their spheres. Was your mind caught in the Nauticam port table when you wrote this? Or was this a quick shot having the 115,53 degree field of view of a general 15mm lens in mind? Not everybody shoots Nauticam 😅 underwater. The lens also seems to work fine behind a 140mm full sphere fisheye dome, with r=69mm. At least it wil autofocus properly. I have not inspected IQ of my friend yet, as the water was very murky, it will need time for results to properly falsify. Looking forward to your comments and also some directions or reading recommendations on how you theorized the required F-Stop.

The misinterpretation that Massimo was targeting with this thread, might have its root in the historic fact that most fisheye lenses usually had the closest minimum focusing distance available. When compared to many other wide angle options in each camera bayonet system they are very often still leading that league.

On Mac AppolloOne is a good tool to browse and look at your image data: https://www.apollooneapp.com

Article Feedback: “When we look at wet lens specifications, we are given the magnification of the lens alone for example 0.36x or 0.57x. This does not mean that if your lens is 28mm it becomes 28×0.36=10.08mm during the process. What it means is that if something is at 1 metre from the wet lens this will indeed look as if it was 2.8 metres and therefore the field of view will be larger.” When reading it, I have a hard time to understand how you derive the 2.8m distance from the factor 0.36x or 0.57x of the water contact optic. Maybe you want to refine this without leaving the reader two choices? Also adding a small line with short computation example would be nic. If this is not computed data at all it’s worth noting that it comes from the EXIF and is empirical from a specific rig combination.

Bravo 👏 Massimo! Amazing ✍️ write up and thank you for your efforts and time you put in this. This is the point where I would like to know what you do for living? I can imagine you have a physics / engineering background or are in involved in optical design.

I am amazed by the fact that shooters discuss this in depth who use Lightroom at the same time! .. noting the fact that bloody LR will reset and flatten your raw files upon import and you have to work yourself backwards on to get what you saw on your cameras LCD underwater. Strobe Color Temperature is highly overrated as it will just apply to - white balance = AUTO - file format = JPEG shooters who want to be done when they exit the water. The following will therefore just apply to a certain type of underwater photographer: - green water = cooler strobe temp - blue water = warmer strobe temp is slightly beneficial for rendering better blue or green background in AUTO WB. The logic and scientific approach is much different: 1.) buy the strobe with the coolest color temp 2.) manual white balance onto that strobes color temp or set the camera to a fixed Kelvin Value of your choice, measurement why? - get the same or even better effect as with AUTO WB - utilize the fact that you are bringing optimized photon energy into the water Kelvin Values can be viewed as the integral under a nanometer color spectrum curve measured. The warmer your light strobe, the more absorption you will suffer from in water. With increasing distance the warm light is the first to get absorbed. Basically you are wasting a lot of energy and battery power trying to don quichotte the water column. Keep in mind that this is not true for very close macro distances, where high CRI and low Kelvin values are considered to be beneficial.

Me neither, but it’s easy to agree to as there is something else often pointed out in their relation with dome ports. “Their circular crafting makes them more compatible with the curved shape of the dome and projected virtual image, when compared to rectilinear lenses.”

Mhh,.. strangely this does not copy my experience with fisheyes in the past. I have to look more deeply into this soonish and re-verify. I can just imagine right now that your sink test shot is extremely stressing the CFWA end and close focus of your Fisheye and therefore looks so disappointing. when quickly comparing optical bench hub I see find also that you cannot really perfectly position the 8-15 canon plus adapter on the npp without vignette? I think you are off by a few cm.. which ist substantial. Am I right quickly browsing this and running the numbers?

By using the 230mm dome you have amplified the optical error and I am really surprised you did as from the knowledge published and rehearsed on your website you certainly know better. I have some of my sharpest shots, including sharp corners with a fisheye behind a correctly positioned full hemisphere dome.

Can you verify this is @ 16mm zoom position? Did you host the fisheye in a full hemisphere dome or rape it in your 230mm zen dome? Maybe you can elaborate a little more and fill us in on the details. I must say that in your blog you were previously very positive about the Canon 15mm and Canon 15mm Kenko 1.4x TC. So I am surprised to see your latest sink shots look like this with it. Generally there is a high chance of having to live with a mispositioned Canon 8-15mm Fisheye. Without full sphere you can almost be sure to throw away some light rays. The “Fisheye Bonus” cannot buy back the misalignment of the entrance pupil. Therefore I will try the old SIGMA 15mm EZ DG f2.8 Fisheye and not the Canon. I hope this does not hijack the thread but I’d love to read more about your previous teasered upcoming blogpost: ” For the purpose of this article I will consider only underwater imaging, split shots and over and under have different considerations and will be addressed separately in due course. “ source: https://wp.me/p2QoIB-k3J Maybe we can touch that quote in the course of this thread and also work out the better split shot lens? Rectilinear vs Fisheye

Inspired by Massimo and a comment in another thread I would like to gather intelligence for underwater photography in the RF System and point your attention to one of the most unpopular and underestimated wide angle lenses for full frame canon camera bodies: Canon RF16mm F2.8 STM https://www.usa.canon.com/shop/p/rf16mm-f2-8-stm is what we talk about. Lens data available at: https://photonstophotos.net/GeneralTopics/Lenses/OpticalBench/OpticalBench.htm#Data/JP2022-085382_Example03P.txt,figureOpacity=0.25,AxisO,OffAxis Underwater dome port & travel benefits: 1) very low minimum focus distance of just 13cm 2) minimal weight and size ( just 165 g ) 3) very affordable price (less than $300) some cons / stuff to watch more closely: 1) the lens moves the npp ( entrance pupil ) more than 6mm during focussing 2) has already some vignetting and chromatic aberration topside, which will not disappear when stopping down Do you shoot it? You like it? please share your thoughts and test shots in this thread

I have looked into several domes more closely last week and would 2nd that statement. If the dome is not full sphere usually the optimal position limit ends with 14mm Full Frame lenses. Therefore, for fisheye, the smaller dome is very often the better solution when it is a complete hemisphere. Full sphere rules out dome size for fisheye lenses.

Well,.. I agree when solely looking at the minimum focusing distance but strong vignetting and chromatic aberrations make it a less interesting candidate.

I should clarify that I am talking about the cheap RF 15-30 IS STM wide angle zoom

I would like to raise awareness for this lens and the funky 128mm minimum focus at 15mm wide zoom position. Its only available if you set the focus manually, in AF it’s a whopping 28cm. I am pondering with the idea to use this lens in MF and pre-prep it for the virtual dome image focus point. Entrance Pupil is located 97.69mm from sensor plane. I am using it with a 114mm radius custom made dome and am able to position this with just 0.09mm offset on the entrance pupil. Almost perfect. But not sure if my theoretical guessing is right. it would be great to have a much tighter lens than a 10mm or my fisheye for splits. Do you think this will allow me to shoot wider aperture than F22 with still good overall sharpness in splits?

Romy, actually I think Interceptor did not intend to insult you or your photographic work. So please be gentle with each other. On the fact side: if you or somebody else wants to know if you got the best technical equipment combination, you have to go bathtub/pool or lab test. Interceptor pointed that out correctly. The dynamics involved in real imaging on the reef are too flexible to know what the gear will be able to deliver at best. There is so strong impact by the visibility conditions for example. Furthermore many photographers shoot their lens and dome too wide open or focus mispositioned. A lot of lenses may be used, but should not be used behind a dome for maximum image quality. Of course manufacturers will house these for you anyway and not go into a deep and cumbersome discussion with a customer who has his own opinion about these things and is about to buy.

Thanks for your profound input Massimo. The enclosed depth of field (DOF) and hyperfocal table from the PhotoPills App might also be taken into consideration for further expectation on IQ and split performance. The appearance of affordable high quality 10mm lenses for full frame puts domes back in business and on a new level and is likely to outperform Nauticams Water Contact Optics. We simply never had such a technology available in underwater photography with dome ports until this lens showed up. Before there was a Samyang/Rokinon 10mm f3.5 and the Canon EF11 and RF10 Zoom, but they were more costly, bulky and did not have the amazing low 12cm minimum focusing distance this LAOWA introduced to the game.

I think, we found the misunderstanding. I left aside the bold marked „front surface of the dome“. So I can live with: 4 times the radius of the dome glas OR double (true) glas diameter on full sphere hemisphere domes We mean the same but talk differently about it, depending if your viewpoint is from the front glas of the dome or the Centre of the dome hemisphere. The mathematics behind domes shows that for a subject at infinity the virtual image created by the dome will lie in a position which is 3 x the radius of the dome in front of the front surface of the dome. However there is an inherent problem with this virtual image, because not only does it lie in this position close to the dome but it also effectively lies on a sphere concentric with the dome and with a radius of 4 x the radius of the dome. So when you where writing about the minimum f-stop you where looking into the curvature of the resulting virtual image and running the approximated required depth of field through a DOF calc on a 10mm lens?

Massimo, please share your math with us.