If you recently bought OMD EM10 and a Nauticam housing

[Interceptor121]

Few port suggestions on my last blog

Guide to Micro Four Third Lens and Port selection for Underwater Photography | Interceptor121 Underwater Photo & Video Blog

 

[boletus1973]

hi interceptor.... with my em5 and pana 8mm, the 3.5 minidome is perfect also in 4/3 aspect.... and you can go really close to the subject.... more than the 4.33 that i have....

 

[Interceptor121]

There is a vignette issue with some cameras. In any case when I look at it the issue becomes lighting closer than 15 cm from the tray you can't keep the strobes pointing forward so there is not much point getting closer. I have seen the tests that Alex mustard did and discussed this with him. In theory there is also an issue of corners but that's not something I would bother at this stage

I have added the following to the post

The issue of the 3.5" port has been put forward again with the argument that it allows you to get closer than the 4.33" dome with the Olympus EM5. I do not have an EM5 but I do have a Panasonic GX7 the end of the dome is 9 cm away from the focus point and this means that the dome allows you to get closer than the minimum focus distance of the lens of 10cm. As the dome is shorter than the minimum focus distance on the GX7 the 3.5" port does not bring any benefit. Furthermore as trays are in general around 30cm you need to be around 15 cm anyway to be able to illuminate the subject properly with edge lighting, in virtue of this I remain convinced that the 3.5" port does not bring any real benefit except is a bit cheaper and may vignette.

 

[boletus1973]

There is a vignette issue with some cameras. In any case when I look at it the issue becomes lighting closer than 15 cm from the tray you can't keep the strobes pointing forward so there is not much point getting closer. I have seen the tests that Alex mustard did and discussed this with him. In theory there is also an issue of corners but that's not something I would bother at this stage

there is no vignette with em5.... for the strobes i agree that is difficult when you are really close.... but its possible... you need long arms with strobes up and far away, is better shooting vertical with good viz but you can do it...
for the corners... you have to stopping down also with the 4.33.... a little more with the 3.5, but te corners are much better than the oly 9-18...

 

[Interceptor121]

What am saying is that if the 4.33 touches the subject the camera can't focus anymore as the distance is less than 10cm. The two ports differ for 1 cm this may be a benefit for the em5 and irrelevant for other models. Either way you need to be further away unless you want to point the strobes at the subject