Chris Ross

The RF-EF converter does not change the position of the entrance pupil relative to the sensor for EF lenses, so you can use the same EP distance in your calculations. The 1.4x or 2x however does move the relative position and you need additional extension equal to the flange-flange length of the tele-converter. I'm assuming you are talking about change of entrance pupil position as the 8-15 lens zooms, it appears to be a minimal change for this lens.

The main difference for UW photo purposes is you don't need to use microscope mode for macro. Microscope mode imposes some limitations compared to be able to use Av. On the TG-6 you can use supermacro AF which basically means you can between shooting larger subjects and small subjects without changing modes. Probably a good advantage for a camera you want to use when you cant use your full rig.

The missing data is what focal length you shot at, you need to zoom into 10mm on APS-C to get the full 180° diagonal, or whatever field you get with the 8-15 at 15mm and at a 1.2x crop need to zoom into I estimate 12.5mm to fill the frame. The fields of view would be: 1.2x crop horizontal vertical diagonal 12.5 147 94 178 13 141 90 169 15 120 78 143 APS-C 10 144 92 180 13 107 70 132 15 92 61 112 You can see on APS-C the field is very close to a WWL at 13mm zoom and at 15mm on the 1.2x crop you are slightly wider than a WWL. 15mm zoom on APS-c lands you with a similar field to an 18mm rectilnear across the frame. The projection of a WWL is very similar to that of a zoomed in fisheye lens and people often use the Nauticam wet optics for video. The very worst distortion is in the corners on a fisheye and this rapidly reduces as you zoom in. I would think a full 180° fisheye would be an issue on video - on reefs you have fish coming from all angles and if one swam in from a corner it would change shape quite dramatically as it crossed the field. On the WWL and zoomed in fisheye the corner distortion is less extreme and changes in fish or other subject size is not noticeable and I think this is why you find it usable for video and of course the curved horizon is less noticeable as well. The real test would be to have a shark or turtle cross the frame diagonally to see how that looks . You can of course edit out extreme changes, but it would be nice not to have this as a concern.

We have some!

Nice work, a cool looking fish, i guess you didn't test out it's electric capabilities? We have numb rays around Sydney which can deliver quite a jolt if you step on them, they bury in sand and can zap divers who accidentality touch them.

If you find some old Canon FD lenses, they sit with the aperture at f5.6 when not mounted to a camera, so stopped down a little more than many wide angle lenses and available quite cheaply. You can also find accessories in the FD system the macro auto ring which attaches and allows you to stop the lens with a double cable release, though using that UW would be an issue of course, but it might be possible to adapt it to hold the aperture open? The Canon FD system had a really complete macro system with huge number of accessories, here's an old brochure: https://www.galimbertipaolo.it/CanonFD/MacroBrochure1982.pdf

The 12-50 really isn't a great wide angle solution - 24mm equivalent is not that wide and through a flat port it has the field of a 31mm lens. You could possibly use the WWL-C with the 12-32 lens, but it appears the ports offered by Aquatica are too long. You could use it with the 12-50 lens on your macro port assuming it fits the the same port as the 60mm macro, but the range is less and on the wide end would be around 16-17mm full frame equivalent and you would need to figure out a way to attach the bayonet.

If the same port is used with the 60mm and 30mm macro, then no question you want to use the 60mm macro. The 30mm lens is shorter and won't work as well as there is too far between the lens and the port glass. If you look at the port charts, the magnifications are 60mm bare gets 1:1, the 60mm plus CMC gets 2x magnification, while the 12-50 only achieves 0.8x. If you are only looking at macro and not considering flexibility , no question use the 60mm , it's far easier to use a 1:1 macro compared to adding a CMC to another lens that needs the CMC to achieve 0.8x. Plus the 60mm can get 2x with the CMC added. The WWL-C is probably a better solution than the 7-14 (presumably Olympus) which is nice but is probably not as good in the corners and would have slightly more reach plus it focuses very close, so could do CFWA, which the 7-14 and 12-60 won't be as good at. The 7-14 has about the same horizontal field at 7mm as the WWL-C at max angle of view. But it probaly depends on what you want to do with it.

Nice looking lights, and it seems very well thought out with quality components. Though I would suggest cats and o-rings don't mix!

Welcome to Waterpixels, hope you enjoy the forums

I suspect the explanation is quite simple. LED brightness is proportional to current, and this will drop as voltage goes down. As the battery discharges the voltage drops and the LED dims. The cheap lights don't dim to preserve batteries, they dim because the output voltage drops as the battery discharges as they don't have the extra circuitry to keep the constant current required to maintain brightness. Brightness is generally controlled by PWM (pulse width modulation) which switches the LED on and off rapidly to change the average current. I would think the cheap lights just have the PWM circuit to provide the preset brightness levels and as the battery voltage drops so the current drops and the LED dims. There are a few ways to keep the current constant - a DC-DC constant voltage converter that supplies a constant voltage until the battery voltage drops to a pre-determined level. Another way is a constant current power supply.

There are two advantages for long focal length macro lenses, extra working distance and narrower angle of view making backgrounds easier to control. The narrower angle means that a small move to either side can move distracting background elements out of the frame. On land this can be a big advantage. The magnification on the 180mm macro is the same 1:1 as the 105mm so no advantage. For many subjects extra working distance is not usually needed and the extra water means more particles and potential for backscatter. The sole exception probably being portraits of smaller fish and other subjects which can move quickly. The extra working distance also eats into strobe power. The narrower angle of view also won't help you UW if you have black backgrounds, though it may make it easier to exclude nearby objects at a similar distance. The 180mm is a nice lens but it's one of the very first L range lenses released in the EOS system so the autofocus can be quite slow. I have one that I have used extensively on land for insects and other subjects that are hard to approach .

Have to agree, on land I don't often use high frames per second and in water I'm always on single shot. The other consideration is hours of sifting through near identical frames when editing after the dive. I'm sure there are situations where you could make use of the high frame rates, but not a big priority for me.

For most practical purposes as long as the the flash duration is less than your sync speed it doesn't matter. In some situations where you want a very short flash duration to freeze motion it may make some difference. For example using the old YS-250 at full power with a duration of 1/50 would not be that effective in stopping motion blur as an extreme example. As for HSS duration may make some small difference, but when using HSS the pulses are all very short - just like very low power pulses so you will not be up against the the maximum duration. For example if you were trying to HSS at full power which is the longest duration you would only get one pulse and the flash would need to recharge. HSS emits a great many very low duration pulses during the shutter travel time, so each pulse is nowhere near the duration of a full power pulse.

It's strobe lit, they match the kelp really well without strobe lighting, the Sydney ones are particularly colourful.

Yes Rapid Bay is good for Leafy Sea dragons, however weedy sea dragons are not common there. The water there is also cold in October.

You can just take a constant zoom ratio (50/24 * 10 = 21) but that doesn't hold between fisheye projections and rectilinear ones. I did some calculations and it appears that the WWL-C follows something close to a stereographic fisheye projection and you can calculate horizontal and vertical field from that: What Nauticam quotes is a 130- 72° diagonal field which is equivalent to the diagonal field of 10-30mm lens, if you compare the horizontal fields it matches the field of a 12.2 - 31mm lens with a slightly smaller vertical field.

I've never dived Flinder's Pier, The image I posted is from Kurnell in Sydney. They are not really all that seasonal, in my experience. The image posted was taken in December. I note that you are from Singapore, so you might not be used to cold water diving. The average water temperature in October at Flinders is reported to be 14°C so a bit chilly, particularly if you are not used to it. Kurnell at this time of year will likely be warmer - something around 16-17°, but it is quite variable. The difference between 14 and 17°C is significant in that you will really notice the difference! You would need a minimum good quality 7mm wetsuit - the rental suits at least those they rent around Sydney are often in average shape. Plus gloves and hood or hooded vest. Regarding Leafies, they are not generally found in Port Philip Bay, best spot is Rapid Bay Jetty south of Adelaide.

I don't think anything equipment-wise is needed. Photo could be a tad brighter, Main thing I would suggest is approaching from a different angle so you don't have the hydroid cutting the fish in two. If she is not using astrobe that is an obvious first step, an INON S220 seems like a good strobe to suggest for macro work.

Basically when I say the lens is at infinity it means it is focused to infinity, so in simple terms the distance scale shows infinity. When the lens is at infinity focus, it is the minimum magnification and maximum working distance you can achieve and in this particular example the working distance is 93mm with the SMC diopter you mentioned as indicated on the port chart. It can then focus all the way to 1:1 on the lens which with the diopter gives you 2.2x and 45mm working distance.

I agree however the biggest issue is that the more complex lenses tend to be fast, with big front elements and the manufacturers don't make versions of them that have the entrance pupil in the range where it is compatible with the WWL/WACP series of wet optics. An additional consideration is that to achieve the resolution some of these newer wide angle lenses are capable of everything needs to be near perfect, and this would include not stopped down too much, good entrance pupil position in the case of domes and not shooting through too much water.

The WWL is a 130° field on the diagonal axis however it is stretched significantly more in the corners due to the barrel distortion. The horizontal field works out to be about that of a 13-14mm full frame lens. It is equivalent to a 10mm or so rectilinear lens only on the diagonal. I would think using the horizontal field which has a slightly magnified image scale as input to the stabilisation routines would probably be the best bet as it is the effective focal length for most of your subject.

Travel insurance got the extra flight expenses, accomodation expenses and the resort gave me a full credit and I booked again in May. Hardest part was getting Air niugini to let me use my flight credit for the domestic leg. The diving there is great., pretty warm and humid topside, made the splash into 30 deg water seem refreshing.

In general yes, but in trying to deal with the virtual image they create in effect a flattened version of it and also increase the field coverage. The net impact likely depends on how the lens in question copes with the new image being fed into it by the wet lens. One example is field curvature in the base lens may cancel out some of the curvature of the virtual image or is the curvature is in the opposite direction may make it worse. The original premise when the WWL was first created was that the dome optics degraded the image to an extent that the properly corrected kit lens could out perform a premium lens like a 16-35 f2.8 optic when it is placed behind a dome. Some of the analysis done on these forums indicates however that this is not always the case it seems. The de-magnification done by the wet lens also shrinks the image scale which also means the aberrations are also shrunk along with the image so become less noticeable. Of course depending on how the lens interacts with the wet lens it may introduce its own abberations.

Some More images: A Square spot Anthia, likely it was at a cleaning station: More Pink anemonefish: A busy scene with Clark's Anemonefish at 30m on Kimbe bommie. Baitfish schooling : A WWI Japanese zero fighter wreck in 17m, quite close to shore: