Hello,

A few weeks ago, I returned from a liveaboard trip in Indonesia, where I used a OM Systems OM1 camera, AOI Pen Housing, and the AOI 8 inch glass dome port. I also had 3 backscatter strobes and the 60mm macro lens and port.

The Olympus 8mm 1.8 is quite sharp and is capable of close focus. However, at times, I was frustrated using the 8-inch dome port. I found that I couldn't focus quite as closely as I would have using the 4-inch dome, and there were times when my close-up images were difficult to light due to the size of the port and the shadow it cast. I am still working on perfecting my strobe placements, so part of this could be attributed to my technique. Another problem I encountered was that at times the 8mm fisheye was too wide, and it was so easy to get bright edges. Again, I'm sure much of this had to do with my strobe placement. I'm am now thinking about how I will approach my next tropical trip. I'm considering adding the Olympus 8-25 f4 zoom, which should be compatible with my dome port. At times, being able to zoom in even a little bit might be advantageous, and, of course, it is a rectilinear lens, which can be both good and bad. However, I have read numerous reports that suggest using the 8mm fisheye is the best option. I have also considered going with the AOI 4-inch glass dome; however, I hate to buy a new, expensive port, especially when I have the old Olympus 4-inch dome for the 8mm lens. Unfortunately, AOI has told me it won't be compatible with the new pen port system. Others on this forum suggested that the 4-inch dome was the way to go, but the salesman I purchased from convinced me to go with the 8-inch. I was told it would render a better image and is the way to go for over and under-shots. All this being said, I find that when I'm out diving, it is best to have two choices, macro or wide. Throwing in a thrid option makes things more confusing not always knowing what will work best.

The most significant improvement I hope to make is more practice and training. Luckily, I have two more trips coming up this summer.

Particularly with m43, there's minimal image quality advantage for using a large dome with a fisheye lens, though an 8"dome certainly will with over-unders.

It looks like the only Pen housing to OM-D port adapter sold adds 37mm of extension which is too long to use with your 4"dome. The thing to be aware of if you went with the 8-25 is to resist the temptation to zoom in too much as opposed to getting closer. You do of course lose the fisheye effect if going that way.

I think it's probably best to practice more with your strobe placement, particularly getting them well back behind the dome.

I love my fisheye - i have rarely used a rectilinear wide angle since switching to fisheyes in 2008 or 2009.

No, they aren’t as versatile - so if your goal is to get a lot of good shots per trip, a different lens might be better. My goal is to get a few great images per trip, so I am willing to sacrifice some versatility for that.

Strobe placement will change a lot when you change the dome, especially if you are habituated to the old dome. I switched to Supe DPro after nearly 2 decades of Inon and I still get the strobe placement wrong at times, as muscle memory takes over and I forget to account for the much wider beam. Worth pushing through it, I feel.