OMD EM5 and Pana 8mm Fisheye which dome

If he is shooting right in front of the port for CFWA that will work well. If instead you shoot 3+ feet away and the water is murky probably a bit on the short side

Sounds reasonable.

Quite a few of my shots are WA, but not CFWA. For that, I prefer my 5"+7" arms completely extended, and even then, they're often on the short side. OTOH, longer arms would make for an unwieldy rig, and I might just as well be shooting with a dSLR rather than an m43. When I try my hand at CFWA, I pull the strobes closer to the housing, but I don't think I'd be particularly happy with so short arms.

Of course, my Nordic waters are usually on the murky side (5-15m viz), so long strobe arms are sort of de rigeur...

Quite the opposite get closer with fisheye lens so you need short arms. Obviously with a rectilinear lens the arms get longer and longer. Either way even with 5+7 is backscatter at two feet

Quite the opposite get closer with fisheye lens so you need short arms. Obviously with a rectilinear lens the arms get longer and longer.

That didn't make sense to me. Care to elaborate?

The closer you get shorter the arms with a fisheye lens you can shoot on the dome and still cover a wide area. Maybe the example from Phil is excessive and I would still go for your configuration but don't think you can shoot a meter away that is not the case. You can probably cover 0-50 well and more in clear water without backscatter not so much more

The closer you get shorter the arms

That's obvious. I just don't see the big difference between a rectilinear WA and a FE (provided subject distance is similar)

--

Sent from my Android phone

Typos are a feature, not a bug

A lot of difference

At 10 cm horizontal field of view on 18mm 20cm on fisheye 75cm on average 3.5-3.75x for the same distance. Obviously the strobes can't cover the whole field of view but with two twins 110 degrees you do cover a lot of ground around 50-55 cm that a rectilinear lens will not cover

Regarding the ports listed above the ZEN port is for the Olympus housing not the Nauticam housing. The Nauticam version of the ZEN 100 mm fisheye port is different. Nauticam now also offers a 140 mm optical glass Fisheye port that works with the Panasonic 8mm fisheye. Not all of these ports are equal and if you look at the Nauticam port chart and the ZEN listings you will see that some of the ports are listed as FISHEYE ports this reflects the differences in the shape of the dome compared to those optimized for rectilinear lenses. I use the ZEN 100mm port for both the 8 mm and the excellent Olympus 12mm F/2 lenses. Both work quite well with the port for close up subjects. Both of these lenses focus very close 10cm for the 8 mm and 20 cm for the 12 mm which is measured from the sensor. So in effect both lenses will focus all the way to the glass or mm's from it. Using a +2 or +3 diopter closeup lens on the 12 mm just reduces the AOV of an already excellent lens with little to no upside since the lens will already focus within the focus range created by the curved port. For over/under shots and those taken from more that 2/3rd's of a meter you are better with a larger port like the Nauticam 140 mm or 180 mm or the ZEN 170 mm.

Shooting very close with the 100 mm dome using the strobes pulled in very close to the housing actually reduces the amount of backscatter for two reasons. #1 the strobes can be placed well behind the dome port and #2 they can be turned outward to reduce the amount of light going to the center of the image. These are issues of technique and require much practice. When the port is within a few mm's of the subject you need only light the foreground subject and the rest is A/V light. With a larger port or even the 100 mm port from more than 2/3rd's meter I would be inclined to move the strobes onto longer arms. The strobes can also be mounted directly to the strobe mounting points on the tray or grips with no arms. If you don't intend to do CFWA with the Panasonic 8 mm you may want to consider the Nauticam 140 mm optical glass port.

Images with the 8 mm and ZEN Underwater optical glass dome both within a few mm's of subject.

So for extreme WA shots of wrecks Phil, the 140mm fisheye dome would be better?

Sent from my iPhone using Tapatalk

I would first say that as of today I have not yet tested the Nauticam 140 mm optical glass dome port, however I think it will be my choice for the coming Olympus 8 mm F/1.8 fisheye. For extreme W/A shots I can't help but think it would work better than the domes in the 100 mm +/- range.

the coming Olympus 8 mm F/1.8 fisheye..

--

Sent from my Android phone

Typos are a feature, not a bug

I would first say that as of today I have not yet tested the Nauticam 140 mm optical glass dome port, however I think it will be my choice for the coming Olympus 8 mm F/1.8 fisheye. For extreme W/A shots I can't help but think it would work better than the domes in the 100 mm +/- range.

I thought the larger dome are more a rectilinear lens issue thought they can be useful for split shots

Unless of course the lens can't focus close. The panasonic focus at 10cm that's pretty close

I have attached a link and photo for stoker regarding the new Olympus 8 mm F/1.8 fisheye PRO and you can also see the new E-M4 MKII and other new releases. An Olympus 7-14 F/2.8 PRO zoom is also coming in the next few months.

If you look at the Nauticam port chart and the ZEN Underwater as well you will see that some of the ports are listed as dome ports and others are listed as fisheye dome ports. There is a clear difference in the curvature of the glass/acrylic between the two. This is not to say that the 8 mm fisheye can't be used in a dome port and that a lens like the Olympus 12 mm F/2, a killer lens can't be used in a fisheye dome port but performance may vary with each.

Interceptor, In regard to the Nauticam 140 mm optical glass dome port I was answering a question from theatricster regarding his interest in extreme W/A wreck shooting. What I said is that for that type of shooting I think the 140 mm may be the best choice. For CFWA the lens would basically be focusing inside the port and very close to the lens. In the case of extreme CFWA a smaller fisheye port like the ZEN 100 mm optical glass would be the better choice. The 140 mm fisheye is also recommended for fixed focus fisheyes for Canon, Nikon and if Sony FF ever do a fixed fisheye (not a 28 mm plus fisheye converter) offering I would guess for that as well. Regarding the new Olympus 8 mm fisheye I am sure it will be close focusing.

http://www.43rumors.com/page/3/

I have attached a link and photo for stoker regarding the new Olympus 8 mm F/1.8 fisheye PRO

If you look at the Nauticam port chart and the ZEN Underwater as well you will see that some of the ports are listed as dome ports and others are listed as fisheye dome ports. There is a clear difference in the curvature of the glass/acrylic between the two. This is not to say that the 8 mm fisheye can't be used in a dome port and that a lens like the Olympus 12 mm F/2, a killer lens can't be used in a fisheye dome port but performance may vary with each.

--

Sent from my Android phone

Typos are a feature, not a bug

The 4.33" is a proper emisphere. The other ones are referred as ports because are a slice of a larger glass with bigger radius. Those are suitable for wide angle lenses so that you don't require the whole larger dome. The nauticam 4 and 6 ports are examples of those. Most likely the 4 port is a cut of a 6 and the 6 a cut of an 8. So for example if you go and try the 4.33" it may not focus and require a diopter.

I have the acrylic nauticam 4.33 port, and I did manage to scratch it pretty badly right dead center. The 8mm lens is really eager to focus on the scuff, especially in blue water without any other obvious subject. Whale shark coming? yeah, here's a photo of your dome.

I've managed to buff it out, but the dome is so small that it's a little hard to work on. The abrasive kits remove the bad scuff, but then leave a bigger ring of slightly less scuff, which the next abrasive can take out, but then the circle bigger, on to the next abrasive.... it gets harder near the edges to work the abrasive smoothly, and I find it much easier to do on big domes. Your milage may vary.

Personally, I'd go glass at the athena price point but not at the zen price point.

#1-121 is correct in saying that the Nauticam 4.33 inch acrylic dome port is a hemisphere and suitable for fisheye lenses like the Panasonic 8mm M43 lens and the Sony 16mm NEX lens with fisheye adapter for APS-C sensors.

Rodger makes a very good point regard those buying these ports for extreme CFWA. If you do this type of photography you can help but bump your dome port against something solid sooner or later. Because the 8 MM focuses all the way to the port glass even a water spot on the dome or a smug on the inside of the port can cause the lens to focus on that point and not on your subject. This is where the optical glass dome becomes so much more useful. Look at the NauticamUSA site and search for the post by Chris Parsons where he jammed a ZEN Underwater optical glass port into the aluminum ladder on a dive boat leaving a layer of aluminum of the surface of the glass. They aluminum was remover with no damage to the glass. With acrylic the dome would have been deeply gouged. In the case of a proper port for the 8 mm fisheye you get what you pay for and to me the Zen 100 mm port is still the best choice.

Another benefit of glass is the anti reflection coating that allows you to shoot the sunball directly though this may have other challenges. Down size obviously the size. I think Scott from bluewater photo made a whole lot of tests and for normal shooting no image quality difference could be seen between plastic and glass. The benefits kick in from other perspectives.