Chris Ross

Some great diving in PNG - Walindi resort on New Britian island has excellent diving on seamounts.

The other consideration is that you can get by with smaller cheaper strobes on m43. I used the Z240s a lot till I got Retra pures, but tests on here showed the tiny cheap INON S220 have similar output to the Z240 and I'm sure would be quite enough particularly for macro on m43. You can do this as you don't need to stop way down - f8 is my go to when I shoot with fisheye - both the Panasonic 8mm and the Canon 8-15 and I'll drop back to f5.6 on occasions. On full frame you are shooting f11-13 generally. Macro I shoot at f10 mostly - FF often stops down more than this, but it's not so much an advantage as the strobes are very close to the subject. Opening up means you need less flash power. On the other side of the coin you can mostly shoot at ISO200 making it easier to get sunballs and you also undo some of the gains of FF where you might often use ISO400. on HSS you can use the Nauitcam flash trigger to get 1/400 without needing to resort to HSS. On the rectilinear front I recall seeing a post on shooting the excellent 12-40 lens in a 140mm dome - much more compact if 24mm FF equivalent is wide enough for you if you need a rectilinear. You can go smaller and lighter on the lens side using the excellent 12-45mm f4 lens as well. and the 140mm dome will also suit a fisheye lens well. On the Isotta side you could use their 6"dome for these lenses for a very compact rig.

Back button focus for at least 20 years, separating out the focus from shutter release makes life easier and the Nauticam thumb lever means it remains easy UW. Different cameras have different options, but ideally you want AF only on the back button as if it remains on the shutter release the camera will attempt to refocus when you take the shot. On some cameras the options are all together on one menu line, others you turn on BB on one line and turn off AF on shutter release on another menu line I find I can judge using it stop the lens hunting and also for the classic focus and re-compose, use it for all shooting. Can help when the camera for eaxmple doesn't want to focus on a shark body on the shadow side - just move to place the AF point on a fin and recompose. Once you learn it, it becomes second nature.

With the OM-1 you have 1/250 with the little mini flash and can reach 1/400 without HSS using the Nauticam flash trigger. You mentioned less noise with 24.5 MP on the Nikon, you have about 1 - 1.5 stops less noise on the Nikon - great but with m43 the smaller sensor means you can shoot at f8 with your wide angle lens instead of f13 with the Nikon and you've got most of your noise back as you can run a stop lower ISO. Dynamic range is a similar story. I rarely shoot anything other ISO200 UW, the OM-1 base ISO. My opinion is that the 20MP sensor on the m43 cameras is more than adequate for 95% of people, there are cases where you might justify full frame, selling images for a living is one, really low light shooting is another but the OM-1 does surprising well at quite high ISO, finally printing really big. the 20MP OM-1 prints natively to just about A3 size at 300 dpi on an uncropped image, You could easily do A2 on an up-ressed image. Prints out of these cameras beat the hell out of a 35mm film image - I've done plenty of both prints and the digital print is crisper with better colours and shadow detail. Here is an extreme example(not mine unfortunately), the image is land based but shot at ISO10,000: Hummingbird image ISO10,000 I'm not saying you shouldn't go full frame - if you can afford it and are prepared to lug it around sure. I used to try to ensure I could print all my images as big as practical, but after 40 years I can count on the fingers of one hand the times I've actually printed to something approaching A2 and only a handful greater A3. These days give the easy to use and transport m43 rig it's more than good enough for me.

This may be the "correct" position according to placing the entrance pupil at the centre of curvature of the dome, however I believe the 140mm domes are not quite 180° domes. The Canon 8-15 I believe is 175° across the diagonal at 15mm, while the 7-14 is quoted to be 180° at 14mm and have a 190° field for the circular fisheye at 7mm. What this means is likely the 8-15 can sit right at the centre of curvature and the 7-14 will need to be slightly forward to avoid vignetting by the dome. At 7mm it will need to even further forward to avoid vignetting of the circular fisheye image. Based on this it might be OK with a longer extension at 14mm but need the 20mm extension for circular fisheye images at 7mm. The calculation you quote doesn't take vignetting into account, this happens for a number of lenses, including for example using lenses wider than 16mm in the Nauticam 180mm dome. You can test for vignetting on land, just setup the housing and dome and you can pull the camera in and out of the housing to zoom and replace it to check. If you are not interested in using the 7mm end the longer extension you calculated might work for you.

it'll be more expensive for the housing, plus the N120 ports and extension rings will be pricey and your are back to needing big ports for rectilinear wide angle shooting. Price out all the components to see what you are up for.

I've used the 30mm Panasonic a bit, the problem is 1:1 is so close to the front element you hardly have any working distance. 1:1 is achieved at about 22mm from the front of the lens so it's about 10mm from the front of the port. The practical limit is about 0.5x to have a bit of space and to be able to light the subject. Focusing on whip corals can be a challenge, but it's really practice to hold the AF point on the target. I use a single small point. any patterns of focus points may grab the background.

I use the neoprene pouch it comes in to cover the MFO3 during shore dive entries and exits. I pull it off once I reach the bottom, clip it off then re-install on the safety stop. This is rocky entries from the shore with some swell on occasions, it has worked well so far.

I would definitely recommend going with 60mm at least initially. I have the 90mm macro for land use but don't take it UW. The 60mm macro goes to 1:1, but remember it's 1:1 on a m43 sensor, so it is the same framing as 2x on a full frame or film camera. I don't use diopters with it. It's quite adequate for shooting 10mm long nudis and Sydney pygmy pipehorses. The 90mm does 2x natively which 4x equivalent and covers a frame 8mm across. I don't know how good your critter spotting is, but I can't find anything that small locally - it's small and also camouflaged mostly, so really hard to find. and in some surge and you are soon swearing into your regulator even at 1x.

The AF with the 60mm macro is pretty decent on the OM-1. I previously shot the EM-1 MkII and prior to that the EM-5 MkII. The EM-1 MkII was a significant step up over the Em-5 mkII and the OM-1 a slight step up again. The EM-10 is a base model and I understand the AF is not as good. The 60mm AF works really well is you are close in, it can hunt if you suddenly decide to shoot a bigger subject a meter away, particularly if contrast is low with average vis or there are particulates. But it does snap on quickly if the focus distance is similar. I have it set up to use back button AF, controlling AF with my thumb, make sit easier to control AF. The 60mm is a bit long in focal length - 120mm FF equivalent so you may find yourself backing off more than you would like. Several solutions - one is to use the Panasonic 45mm, the other is the MFO3.

I have Retra pures - a model that was recently discontinued, slightly lower power, but it's enough with m43. You tend to shoot wider apertures because the depth of field is wider, so flash power is lower. If you get Retras - get the reduction rings! First thing I noticed after first dive was way less backscatter. It's not immune to backscatter and you still need to position strobes properly , but way less than the Z240s. You also mentioned rectilinears, basically you are stuck with a bigger dome with them otherwise the corners go off, I have used the 12-40 in the Zen 170mm dome around Sydney and it works well, if a 24mm equivalent lens is wide enough for you. One problem with Nauticam and the n85 ports is that some rectilinear lenses are too big to go through the port when you fit the camera/lens and you have to fit the body, then the lens from the front, then the port. The Port on Isotta is a B102, significantly bigger and it avoids this problem They also have a 6"port which will be smaller and probably OK with something like the 8-25 lens.

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No problem. I would suggest that an RX-100 and TG7 are not really interchangeable- the TG7 is a macro machine and does real close ups all by itself. The RX100 and TG7 are more or less the same on the wide end but to approach the performance of the TG7 you need to add on diopter closup lens as the lens does not focus that close and you have the carry that somewhere, plus they are not as straight forward to use and have a limited focus range. Hybrid strobes/video lights tend to be OK at both or perhaps like the Backscatter HF-1 it's a powerful strobes with an OK video light but very heavy and fairly large. The problem is a small strobe can run quite happily on 4 eneloops batteries , while to power a decent video light you need a couple of big 18650 or 21700 Li batteries, either that or they are rather underpowered. this item is made for the olympus housing to attach fibre optics: Backscatter.comOM System PFCA-03 Optical Fiber Cable AdapterOM System PFCA-03 Optical Fiber Cable Adapter for PT-056, PT-058, PT-059 Housing for TG-3, TG-4, TG-5, TG-6, TG-7. I haven't seen one designed for the bare camera, there are generic stick on units that I've seen being sold.

I'm currently using Retra strobes, I have the reduction rings and they have great light. I can get 3 Sydney dives out of a set of Eneloop batteries. The reduction rings make backscatter control so much easier compared to my previous Z240 strobes. The INON Z240 were very reliable for me though, you could add a neoprene sleeve to act like a reduction ring to them or any other strobe. The Z240s are still sitting around, but I can't see me using them again.

Hi Deemoo, I would first say that a TG-7 without a housing will be OK for a couple of years then the seals will fail and the camera will die. The seals under the top panel controls are a membrane seal that the buttons work through and eventually the membrane fails. I always recommend a housing even if it's the OM housing which works fine. Once you add a tray to allow you to add arms to hold your strobe the compactness advantage of the TG-7 without a housing is lost. In the manual the fine print says you should have the seals changed once a year. The housing has the facility to plug in fibre optic cables to trigger your strobes. then you just attach them to your strobes and you are ready to go. As for choice of strobe it's hard to go past the little INON S-220, it's small and compact and has a good beam as well as being quite powerful. If you still want to use the bare camera you can get little stick on ports for fibre optic cables you can place over the flash. If you use manual strobes you can set the flash to low power manual on the camera and any light leakage will be minor and unlikely to cause problems.