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=> Exact: the planport should be at the sortest distance from the front of the lens. This is provided by the 105mm planport. The same you get with 55m planport plus 20mm and 30mm extension (55+30+20=105), but when using shorter lens you can make the port smaller by omitting extensions...

Concerning 105mm macroport: I purchased the 105 macroport and regret it. I wished I would have gone for 55mm macroport plus a 20mm and a 30mm extension - more expensive at the beginning, but this makes one much more flexible, when one wants to use/test other lenses than the Sony 90mm macro... Another vote for the 45° viewfinder. It is extremely useful and in addition spares the neck muscles. I cannot imagine to give it away... Wolfgang

To complicate things, DoF does depend on the dome: the larger the radius, the more DoF...

The luck with the baggage is the point: When you are not able to put your luggage on the desk, when checking in with Satena, it may well happen that your luggage stays at San Andres, until you come back (at least it will cost you a lot of time and nerves to find someone who takes care(this was in our case the problem))...

Thank you for doing the analysis on the Backscatter test photos. I find them very interesting and revealing... #1.: As you pointed out rightfully after your analysis, there is indeed a difference between light distribution between linear and circular flash tubes. It seems there is no "magic" between different strobe brands, but instead the shape of the flash tube matters. Circular flashtubes just produce evener lighting (what remains to be shown with further test photos)... #2.: Second point is color temperature. Some say they do not mind, but others say it is very important. Good when there are filters available (for those who care), but better the strobe is powerful then, as the filters will take away a lot of light... #3.: There are also other, more technical, items as recycle time, HSS, remote control.. etc. that are also important for some of us... Good that different UW-photographers have different preferences what a strobe should deliver (some say any strobe will do it, what is also o.k.). No matter what the preferences are, careful test photos, as the ones produced by Backscatter and analysed by you, will be a precious help for many of us (as is the valued opinion of UW-photographers from their practical expereince)... => In this spirit, I hope you will continue to analyse new test photos, as they will appear (e.g Marelux Apollo). I suggest you produce an article here that is open and can be updated as new test photos become available... Wolfgang

This is an interesting video. My take is: #1.: FCP substitutes WWL-1/WACP-C as it covers a wider range at similar IQ, compared to WWL-1/WACP-C (IQ here means mostly corner sharpness). #2.: When one is interested to make photos at wider apertures and still have good corner sharpness, then WACP-1/WACP-2 is an alternative, albeit at more narrow AOV... => I am still wondering about the DoF issuer raised by Nicolas Remy in his review, claiming that f/13 and more narrow is required for good photos with FCP. With WWL-1/WACP-C, I seldom use f/13, but more often wider apertures (down to f/7.1) with WACP-C/28-60mm. This is also how WWL-1/WACP-C is advertised by Nauticam (3 f-stops better than rectilinear behind planport (WACP-1 is 4 f-stops, WACP-2 is 5-f stops better)). In addition, virtually everybody uses WWL/WACP at wider apertures... This issue needs more clarification by people who use both FCP/WACP-C... => It seems that the only "hobbyist" who dared to purchase FCP is Fruehaufsteher2. I wonder whether the FCP is to just too expensive or whether there are other reasons (f/13 issue?)... At present, my preference is to stay with Canon 8-15mm/140mm dome plus WACP-C/28-60... Wolfgang

The diopter (which SMC was it?) will certainly change DoF, as it reduces the working distance. DoF depends on (i) focal length, (ii) aperture and (iii) working distance. See e.g. the table in the link: https://www.photopills.com/calculators/dof-table The table is for use over the water. For a lens behind a planport, the focal length increases by approx. 33% ("diving mask effect"). There are other inexactness as well, but the table + corrected focal length will give you a reasonable approximation... Wolfgang

Great information, thanks to you and Backscatter ... 👍 Now we know that Chris's analysis gives valid numbers and also can compare the zones between the RETRA testing (in air at 60 cm distance) and the Backscatter testing (in water at distance of 1m). Here the beam angles of the different zones (for Retra calculated from Pythagoras and angular functions):

There is, of course, never a total warranty, but unless there are (small) cracks in the dome to see, it is very unlikely that any implosion will happen... Even small cracks may be no problem (but may impair optical performance), but then better ask at the manufacturer. In a Nauticam housing that I bought second hand there were small cracks to see in the rear window (not just scratches). I made a photo and send this to Nauticam, the response was that this is no problem (and it was no problem until now)... Wolfgang

When this photo was really taken at f/13, as Dreifish read out from the EXIF data, I agree with Dreifish that DOF is very shallow compared to other optics, e.g. WACP-C. When the aperture was wide open, this is what one would expect, more or less. But still it depends how close the soft coral was, when very close you get this even at f/13... Maybe you have a photo that is not CFWA, e.g. reefscene, and was taken at wide aperture f/7 and smaller numbers? Would be interesting to see such a photo... Wolfgang

This is interesting news...👍 As long as the screenshots are taken from a calibrated monitor (no extra contrast, HDR etc...) the analysis is be valid...

I had a similar problem with Nauticam housing last year: maybe half a teaspoon of water inside. I noticed it immediately, as it was in a very cold mountain lake and I got condensation on the domeport what made photos impossible... After the dive, I noticed that three screws of an extension were missing (already as it came from the factory). I wrote to several Nauticam dealers, some wrote this was probably the reason, other said it cannot be the reason. Backscatter was so kind to supply me, free of charge, with spare screws... Until today I do not know what the reason was, but after insertion of the missing screws and fixing the entire part with four screws, I never had this problem again... => I posted this in the old forum. Better have a look on the photo in the first post there and check, whether you also miss some screws (just to be on the safe side): https://wetpixel.com/forums/index.php?/topic/71358-dimensions-of-screws-for-nauticam-n120-extensions/ Wolfgang

Great, thanks. What were the conditions (aperture, but also other parameters)? => The sharpness of the in focus area does not look very impressive, but this is probably due to the data reduction for putting the photos here. Maybe a 100% would show sharpness better...

I cannot follow you, Adventurer: when flash duration (linear tubes) is 1ms to 4ms, you need shutter speeds between 1/1000s and 1/250s and have, more or less (decay of intensity is exponential), the entire light emitted in your photo. Only Sony AIII and compacts are able to do substantially faster sync. With few cameras that are able to sync. at 1/400s (e.g. Sony A1, Oly EM1II or OM-1), you already clip some light from a flash that lasts is longer than 2.5 ms... Even with circular flashtubes that have longer lasting pulses, the action can be frozen to the fastest sync. speed the camera is able to do, at the cost of some light loss. I never heard that such light loss plays a role in macro, as full strobe power is practically never used... I would be interested if you can give the special settings under which you observed these movement artifacts (focal length (I guess this was at WA with quite long exposure times?), shutter speed, aperture, was there ambient light in the play? etc...) - this is very surprising to me...

This sounds logical. In this context it will be interesting to see the light distribution of the Marelux 3 strobe with three linear flash tubes arranged in triangular shape near the outer rim of the strobe front...

I believe that short flash duration is, at present, mostly important for owners of compact cameras and of cameras that have global shutter (Sony A9III). The flash sync. speeds of most present system cameras (1/160s to 1/400s) are long enough to utilize (most) of the flash duration. It will become, however, a more and more important feature in the future... I think there is also not a single feature that is most important for a good strobe and the others don't count. Color temperature, even light distribution, recycle time, maximum strobe power, compactness and flash duration are separate features and each of them has to be good to make up a good strobe... Wolfgang

In case it turns out that only f/13 and smaller is suitable for the FCP, the FCP concept is very different from WWL/WACP: The positive characteristic of WWL/WACP is that it allows to make photos at relative wide apertures, when compared to rectilinear lenses (corner sharpness issue): Most use it starting already at f/7, sometimes even wider apertures, when ambient light is limiting. I cannot observe with my WACP-C that sharpness in the center is affected by widening up the aperture (same with rectilinear WA lenses behind dome). Maybe Martin's FCP was defective and/or the wrong extension was responsible. If not, his findings are certainly not a recommendation for FCP. When I remember correctly, Remy Nicools wrote in his review that stopping down to f/13 and more is required to get enough DOF for the entire image. He did not write that FCP has to be stopped down to f/13 and more to provide good center sharpness... Corner sharpness is, of course, a different issue to center sharpness and the depth of field issue (but DOF and corner sharpness are related: the more DOF, the better also the corner sharpness will be). I am not aware of any comparison, how much DOF is available, at comparable AOVs and distances, when rectilinear WA lenses, WWL/WACPs and FCP are compared (with rectilinear WA lenses, DOF increases with the radius of the dome). Is such a comparison available somewhere? Wolfgang

Yes, 220V (or lower) directly plugged into the charger. The charger has its own line adapter. The weight of the line adapter could be saved when using USB connection and a separate adapter (e.g. notebook charger, but I would go for another powerfull USB adapter as a spare then). Line cord is replaced by USB-C, so not such saving if any (anyhow the cords weigth very little), but USB cord can be used for several applications... => All in all mostly a more symbolic saving of weight (few power adapters and one, maybe two, power strips), but I try to do my best... The accus of our cameras (Sony A7R5 and Oly EM1II) and the accupacks of our focus and night lights (WeeFine) are charged via line voltage as well. I do not see much possibility how to charge them via USB (maybe buy other Focuslights that are powered by AA or Li batteries, but we are not going to invest a lot of money into this little weight savings (teh WeFine lamps are working very well))... Our liveaboards are mostly in Egypt (Egypt and Red Sea are close to Austria). Since years charging in the cabin is forbidden and all liveaboards have special charging areas on the deck. Even on Alex's workshops, when everybody on board is an UW-photographer, the space is enough (but of course, it is crowded)...

Great video, showing fascinating behaviour...👍 Most convict blennies (Pholidichthys leucotaenia) that find in Google have a different color pattern. Is this a variant?

Hi Jerry, Fortunately, UW-photography is regarded to be not a science, but an art...🙂 There are, however, physical principles in photography and also in UW-photography, that cannot be neglected. I fear a little, that we are coming to the stage were we are going to count peas, but I just cannot leave your post uncommented: #1.: I fully agree that the Backscatter "study" lacks info about conditions, I have no reason to brighten the Backscatter communications. In addition, also the screenshots from the videos certainly suffered some postprocessing and therefore also will not give 100% accurate results (There are people from Backscatter posting in this flash forum and I wonder why they are so quiet...). Unfortunately we cannot translate the "Retra zones" in "Backscatter zones" directly. I guess, maybe, that every "zone" in the Backscatter images corresponds to 40° AOV. Then "zone 4" may correspond to 160° (and approx. to "Retra Zone" 3), but who knows? You cannot calculate light intensity projected by a light source that is several cm in diameter at a distance of 60 cm from the "distance square law", since this law is derived simply from geometry and only applies to light sources that are represented by a point (!) without dimensions. For an UW flash this means many meters of distance, until the light source can be regarded as such (=a single point) and this law delivers solid results. Therefore better do it the empirical way and make controlled test photos and measure the light distribution... #2.: It is not enough for an exact study to use a light meter and give a reference to the manufacturer. One also needs to know how to use it and how to make the measurements: In the normalized graph, that was kindly provided by Chris (where all flashes start at (estimated) 72 a.u. at the center), -1 f-stop corresponds to a value of "36", -2 f-stops to "18" (only HF-1 w/o diffuser goes below 20 at "zone 4" in Chris's graph). -7 f-stops would correspond to a value of "0.6" in Chris's graph - this would be practically black. According to the "Retra graph" (posted by Dreifish at the beginning of this tread), the light falloff, already in "zone 1" is between -3 f-stops and -4 f-stops (that would correspond to "9" and "4.5" in Chris's graph) - such strobes would be pretty unusable... #3.: It is not that "...testing in air might not be ideal...", it is just not possible to test UW-flashes in air and draw solid conclusions for UW work. Not only the beam angle will be different in water, also the light scattering will be completely different, as it is almost absent in air, but substantially in the water. As a proof of my statement, please have a look at the light distribution of YS-D2 and Z330 "test images" (both without diffusers; the last two images at the bottom left) from the Retra "study" I post here (again) the link: https://www.retra-uwt.com/pages/flashgun-light-comparison (I hope this allows me to paste the graph into my post, if not, please delete the graph, but leave the link) => I am using both YS-D2 and Z330 for years (also without diffusers), but never have I been able to get such a weird light distribution pattern. This must have been produced by the lack of water in the Retra "study". I see no point in analysing intensities in such patterns (even when the measurements are done correctly, but the resulting f-stop numbers seem to be completely wrong)... Respectfully, Wolfgang

Quite some time passed since the FCP-1 became available. I am sure that several here have acquired one. There should be numerous people now that have long-term experience... I am curious and would be grateful to hear from FCP-1 users: How does the FCP-1 perform in general? Is FCP-1 a complete substitute for WWL/WACPs, just with more range at the fisheye end, or do you still use your WWL/WACP, depending on circumstances? Wolfgang

Thank you all for the interesting contributions...👍 I am currently using a "DlyFull A4" that is very similar to the Nitcore Ci4, but it is powered by regular line voltage. I am considering now acquiring the Nitcore, powered just by USB-C, no extra adapter, in order to save weight for travel... Could I use the charger of my Notebook, that I have with me anyhow, to power the Nitcore charger? It is for Macbook Pro M1, has USB-C out with 96 W. Already now I often exchange the USB-C to MagSafe cable with a regular USB-C cable and use the adapter to charge other items, e.g. powerbank (145 W/25 Ah), handy etc. ... What specs. should a line to USB-C adapter have to power the Nitcore sufficiently and in addition also other items (from Notebook to handy), when acquiring an additional power adapter? Wolfgang

Hi Dreifish, Maybe you could adjust the exposure to a level so that the brightness in the center of the strobe beam is the same. I think then (and when the distance to the object was the same), one could judge easier whether there is a difference in light distribution and/or beam angle... Wolfgang

Yes, unfortunately the Backscatter graphs that I have posted show results from previous generation flashes... Important is, however, that the light falloff from center to border is in the range of -1.5 f-stops to -0.5 f-stops, depending on zone, flash and diffuser. This is much closer to the measurements that Chris made with your screenshorts, assuming he used a linear y-axis (?). So maybe Chris's measurements are not so far away from reality (but maybe not, because of the postprocessing problem, we need unprocessed test images)... => In any case, I find the graph from the "Retra-Study" weird (and as I wrote already, also the test photos look weird)- the light fall off in Zone 3 is -6 to -7 f-stops compared to the center (!!). Did they put a snoot on the flashes for testing... ? (seriously: this shows that one cannot test light distribution of UW strobes in air)

Thank you Chris, interesting! Is it this with or without diffusers (which diffuser if any)? Could you please also make a graph with HF-1 (with and w/o diffusers)? In case you normalize the brightness of each individual strobe/diffuser combination to the value at "0" (x-axis), the center, The even/uneven light distribution would be even better visible for everybody. Intensity comparison could be made separately from the even/uneven brightness distributions, just by comparing the absolute values in the center, e.g. bar diagrams... => I do not want to be the party-crasher, I hav a little bad feeling when I write this, BUT there is still a massive problem in all this comparison: Both when viewing the images and also when making quantitative measurements from them (the measurements provide, no doubt, comparable numbers. These numbers are, however, just the result of the intensity values on the processed image; we need, however, the unprocessed images in order to be able to compare.. => A meaningful comparison and analysis of the test images is only possible, when the totally unprocessed RAW files are compared, no processing at all. (in addition, the photos have to be taken at strictly standardized conditions. e.g. distance, clarity of water, camera settings (ISO, shutter, aperture) - hopefully Backscatter is doing so...). It would be great if Backscatter would make the original raw files available... Wolfgang