Chris Ross

It would depend on the type of coating, but I expect it would require strong mineral acid to have any impact, magnesium fluoride is often used as a glass coating and it's reported to be quite resistant to acids. Searching showed that magnesium metal is treated with HF to provide a MgF coating which resists corrosion by acids, much more so than the bare metal.

the method shown below using Levels will automatically setup your colours - providing you have a full histogram with a bit of room at each end to allow you to make the needed adjustments. https://www.photoreview.com.au/tips/editing/advanced-levels-adjustments/ It will properly correct a photo that is under flashed for example, very occasionally it might need a little more green removed or blue added, which you do with the midtones slider in the appropriate channel. Sometimes you might need to tone down specular highlights, but it works well for 95% of images.

The cheapest path would be to adapt what you currently have most likely. Recently another member was looking at switching from Aquatica and went with an Isotta housing and an Aquatica adapter ring: Isotta is well supported in Australia with a few dealers selling them and they also have solutions to use WACP/WWL with their system. Aquatica also have a dealer in Cairns. You could start out with a metabones adapter with your Sigma fisheye. For easy travel a small dome with a fisheye is hard to beat IF a 180° diagonal fisheye has enough reach for you. Another Australian member recently went with an adapted Canon 8-15 on SONY along with the Sony 2x TC. A few members are using that solution it's not as sharp as the bare 8-15 but gives superb flexibility zooming all the way from 180° diagonal to a frame that is wide as a 28mm rectilinear WA lens. I don't shoot Sony but I use an adapted 8-15 on an OM-1 and used it for the entire trip when I went to Walindi in 2024 I get the same field of view range with the bare 8-15 on a m43 sensor.

Where did you see this?, I find Sea Frogs documentation for this hard to follow. It seems they have two different ports with built in extension for their plastic housings so don't really attempt to precisely position the lenses behind the dome. The citeria seems to be just make sure it doesn't vignette. I see they have extension rings listed now, but don't see them mentioned anywhere in their lens charts. On the 8-15 on full frame - it's either 8mm circular of 15mm diagonal fisheye so unless you want circular fisheye you don't need a zoom gear and if you can use it at 15mm without vignetting it's probably as good as you can get in this system. On the 15mm fisheye, it's probably a bit short for your stated interest in big animals, particularly sharks and rays where you can't get quite that close.

Acid won't harm glass, it is alkaline solutions that can etch it. Certainly though whenever you clean glass ports do not let the water dry on there. It causes any salts in the water to concentrate, distilled water in theory should be free of salts but you may mobilize some salts whenever you rinse. The answer is to blow off most of the water (a blower bulb is good for this) then thoroughly dry - use a microfibre cloth.

Welcome Sabine, good to have you here, hope you enjoy the forums.

I waved it around the end of my cable while pressing the TV on button and it quickly fired both on the cable and the sensor itself (on retra strobes) A cable issue is quite possible and I would suggest assuming that is the problem till proven otherwise. The older TV remotes with the LED poking out are easiest to align of course , but a I used a SOny TV remote and it quickly fired by passing the window section over the acble end. In any case Pavel has provided some advice and I would certainly try that first.

This one is relatively easy, Google AI hallucinated and gave you the Nikon F (SLR/DSLR cameras) flange distance. I would think when measuring the flange distance you would want a piece of film in place as it has a finite thickness. Using google without the AI, there are multiple references to the dimension being 28mm and at least one where somebody measured and found 32mm.

A lot of people use them , they are cheap for a reason. Among other things the ports are setup for multiple lenses, but can only have the right positioning for one of them. They will let you get your camera underwater and seal properly and certainly you can take quite good shots with them. The vacuum system is not recommended as it can only be used to test, it's not water tight so you don't keep the case under vacuum while diving, which defeats part of the purpose of pre-loading the o-rings. There is a third party solution though. You could check with UW technics when the time comes if they support YS-110a. They are getting quite old now though.

What strobes do you currently own? The ikelite strobes have their won proprietary TTL system that only works with the ikelite TTL triggers which are now a little cylinder that connects to a housing bulkhead. They used to line inside the housings. I know at leats one person who has had ongoing issues with these triggers. But there is more than one way to solve the problem The new external UW technics triggers could be used on ikelite and assuming you have compatible strobes you should be able to use them . If not compatible you have a wide choice of other strobes you can use. I still think you should consider jumping to m43 generally a great system to use, with a lot more choices for housings and lenses, depending upon which body you choose. You could even use your 10-17 with the metabones speed booster.

Welcome aboard, good to have you here.

First thing to try is a new battery in your trigger. Double check the dial on the trigger is set to the right number. Definitely try it with manual position. Next see if you can trigger your strobes through the cables. Point a TV remote sensor into the cable and press any of the buttons. point the IR emitter into the fibre end. You might need to move it around. If this doesn't work point it into the sensor on the strobe. The IR remote should readily trigger most strobes.

Perhaps, but keep in mind Achtel is built around cinema where fisheyes are not favoured and the there is nary a mention of the Nikonos 13mm, though he does list the availability of some of highly specialized fisheye lenses, though it is not clear if they are water contact lenses. The issue as always is the lack of UW lens tests, air based tests can of course point you in the right direction, but not all lenses take well to being taken underwater for various reasons - one recently discovered parameter is a short minimum focus distance. I suspect there are others such as curvature of field which is readily taken care of on land by depth of field but if it bends in the wrong direction it might not play well with dome ports. I have not seen a convincing explanation of why some lenses are great on land but don't play well underwater - The Nikon 14-28 f2.8 lens is one I know of, there must be a reason for this and quite likely has something to do with not handling the curved virtual image very well. Another is they may be poorly optimized for performance at minimum focus distances.

Interesting ..... Achtel is located 5 minutes drive from where I grew up and less than an hour from home by car going by the address on the website. I don't that I would say forced to use conservative f-stops. You can only force yourself to make that choice. Me, I would rather stop down to where I need for depth of field or - say for a fisheye to get around the dome port issues than get the ultimate resolution - the overall image is most important and it's always a compromise. It seems to me that if you accept the statements from Achtel.com that domes reduce resolution to less than high definition partly due to the curved virtual image that you will be looking at fisheye lenses or water contact optics of some type for the highest resolution. Rectilinear lenses have a flat plane of focus parallel to the sensor while the virtual image is curved at some number of radii of the dome port in use. Fisheye lenses do not have a flat plane of focus, generally it is curved surface which may or may not be equivalent to a hollow sphere. Depending on the fisheye projection the focal plane may be circular or it may be flattened. But in any case it is much closer to the shape of the virtual image formed by the dome than the flat plane of best focus of a rectilinear lens. As an aside the S&S corrector lens attempts to do something like this - basically flattening the virtual image so that the host lens can digest it more readily I expect that the ability of water contact optics to operate at larger apertures is related to the fact that optic acts like a fisheye lens and it converts that image in to a flat focal plane that the rectilinear lens inside can digest. If all of this this is correct looking at land based tests of lenses probably only helps with center resolution it would seem??

Welcome to the forum Chris, good to have you here!

Yes that is indeed the difficulty. It seems to me that the suggestion of looking at Bali might e a good one if timing for the Maldives is not good, the advantage being that there is a huge range of options and flights to get there. this website seems to suggest Nusa Penida might indeed be a good option for the OP. https://www.zubludiving.com/articles/zublu-insights/manta-ray-seasons-in-indonesia

Unfortunately that's internet forums for you people run off on tangents on things that interest them. But seriously - please continue to dig and find resources and test images to make your points.

IMO, you are chasing a tiny improvement at best, there's thousands of great shots taken with the Canon 8-15 with the recommended dome dimensions. The test shots displayed on here of the banknotes certainly didn't set the world on fire. I would be interested to see some shots also - test shots are generally preferred as they are a shot of a flat surface and you don't have to work out if the softness is due to optics or if the foreground is falling out of the depth of field.

It depends on how small a subject you find and want to photograph, the MFO-1 reduces the frame covered from 36mm wide to 30mm wide providing 1.2x magnification. The SMC-3 gets 2.3x with the frame being 15.5mm across with 47mm working distance. The SMC3 focuses between 47 and 103mm and I expect it won't give you any overlap with the MFO-1 range. For me I would also factor in how often I find these things, if it's once on the entire dive trip maybe a better solution for this one critter is to crop?

While this is certainly an interesting exercise, there is a fundamental problem. You will see this notice on sites like optical limits: Please note that the MTF results are not directly comparable across the different systems! what does this mean - it means they are testing the combination of the lens, sensor, anti alias filter, de-mosaicing algorithm and any camera specific changes. But what does this actually mean? Well searching around I found a website that tested the same lenses on different camera systems. They tested a SONY 50mm f1.2 on both a Sony and Nikon camera and on SONY (A7RIII) its peak Imatest score was 3611 at f2.8 while on Nikon (z7) it was 4128 @ f2. There is also a test of a 35mm f1.4 EF lens on SONY, Canon and Nikon. The Canon camera used has an anti alias filter so returns significantly lower scores on the same lens Here is the site: https://photographylife.com/our-canon-and-sony-lens-reviews-will-have-imatest-data-comparable-to-nikon So where does this leave us? We can certainly work out the fastest knife in the drawer in any particular brand of lens if they are tested on the same camera. We know that a 3600 score will pretty much certainly sharper than say a 2500 score, but unless the top contenders are tested on the same system we will struggle to decide which is first place. We could use the plots supplied in the link above to approximately convert between the systems, however they only really apply to the cameras they use for testing. As for the Nikonos test the biggest problem I expect is the fact that the testing was done on a completely different system. The centre score in LP/mm should still be valid for a full frame sensor with the same characteristics - the corners of course are a different story. And to be truly comparable the Nikonos is tested UW, you would need to test the other lenses UW as well to compare them. Then there is the problem of different amounts of water between the lens and target. You could probaly validly compare the 8-15 with a Nikonos 13mm equivalent but perhaps not a 16-35 lens for example.

probably not a known site, but some large things will be there, it was basically one option you could get to from Singapore. The idea was to give you some options to consider with flight schedules. There are lots of direct flight into Singapore but probably not so many destinations you can fly to from there for diving. Getting into Indonesia there are not many direct flights to Jakarta except from Amsterdam, but once you are in Jakarta you can travel anywhere in Indonesia. Some flights AMS-CGK are operated by Garuda, some by KLM, Garuda is reported to be better. Minimizing connections is always a good first approach to travel. Once you are Indonesia there are multiple options to consider, same with the Phillipines etc. On the big animals question often this involves drops in the open ocean well away from snorkelling sites, quite a number of them you are snorkelling/freediving but I wonder how suitable it might be for your daughter? It seems the most likely option for big animals with snorkelling options might be a site where there are manta cleaning stations with plenty of coral/snorkelling spots in the general area. Mantas can be seasonal so you would need to check into timing to visit.

If you look at Pavel's post on his TTL converters on Sea frogs, he shows one mounted on a Sea frogs housing. The housing looked rather stained by watermarks and given they have only been out for a short while this must have occurred rapidly. Brings into question the quality of the surface treatment.

In the Nauticam system it's easy as the camera is positioned in the housing so that you can use all or you current lenses, ports, extension tubes and zoom gears on your new housing. Put it another way the when you use the EF-RF converter the RF port chart has a line item which directs you to use the EF port chart. It does this by positioning the lens flange further back in the housing by the thickness of the EF-RF adapter. That way the the zoom gear will line up with the control gear in your new housing. You would be able to do this with other systems, but would need to buy various extension rings, zoom gears and sometimes ports. For example with Isotta you can convert Nauticam ports to work on Isotta by changing the lug ring, but not extension tubes and the zoom gears won't match. WHen the time comes prepare a spreadsheet to add up all the costs to see what you are up for in total.

Isn't this the same lens that @DreiFish tested and pronounced to have pretty poor optical quality in his thread from a little while back. Consulting google there are some tests that pronounce optical quality to be quite good and others such as the digital picture tests with sample images that pronounce it to be quite poor. I agree there are some very good lenses coming out now, but you still tend to get what you paid for. The searching of reviews suggests that there is a lot of sample variation in this lens so it's a bit of a lottery it would seem about how good the lens you get is. Or perhaps the good reviews received hand picked lenses to test?? BTW the test for the the 24-50 on digitalkamera.de seems to be behind a paywall. While I agree that having a sharp lens is great and certainly an interesting exercise to trying to find the sharpest you can for your UW photography and do not in any want to discourage your quest, when under water IMO flexibility is quite important as you can't swap to a more optimal lens like you can on land. Never mind the Ansel Adams quote: "There is nothing worse than a sharp image of a fuzzy concept"

Yes you can use the Can 8-15 same as the 10-17. You set the zoom limiter to 10mm and can zoom from 10-15mm with APS-C, better image quality, less zoom range, more weight, and can be used on Marelux compared to the Tokina 10-17 Yes you need to read the fine print in the port charts: this is because the small housings don't have a zoom control it must be on the lens extension and all they offer is the 6"dome in this format Regarding the m43 option , I have the OM-1, you have a lot of options for housings and Isotta is a good option if you want to adapt a Canon 8-15. Here is the parts list in this post: SO you could price out this option. I did it with Nauticam, but it ends up expensive as you need an N85-N120 adapter which are really pricey and Nauticam no longer makes the specific adapter and their ports and extension rings are pricey. I got some of the items second hand. You will need the metabones adapter - the latest model EF-M43 is needed due to geometry of the OM-1, but I have an older version I filed down to fit. The image quality is great though. This gallery is all taken with OM-1 and Canon 8-15: https://www.aus-natural.com/Underwater/Walindi%20Resort%20PNG/index.html I did have a few issues with noise on a couple of deep dives on overcast days, but doing it again I think easily compensated by upping the ISO and shooting a little wider open. Shooting at f8 is generally enough so you can use less powerful strobes. If you can source the FML-3 mini flash to trigger strobes it is a cheap and reliable option for manual triggering. Be aware though in Nauticam the housing ends up quite heavy and needs a fair bit of flotation, the small housing size is less buoyant and the 8-15 is a heavy lump of glass.