Best dome port for the Olympus m4/3 9-18 lens

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Nickbell

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Location
Adelaide South Australia
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I have been using the Zen WA 100 EP dome port with my 9-18 and am not overly impressed. The lens is beautiful topside but suffers from what I consider to be unacceptable edge sharpness around 9mm underwater. Most of the posts so far acknowledge this and recommend keeping the most important detail in the centre. As I am hesitant to sell the lens at this stage, can anyone suggest a better port (I am not criticizing the build quality of the Zen, only the results). Will the Olympus ppo-eo4 with an adapter to fit the PtEP11 (em1) give better results (although twice as big). I also have the 8mm panasonic fisheye which I used on my epl2 with the appropriate zen Dome port and was after similar quality ( but not as wide). Just ordered an Athena dome for the 8mm and the em1 and will report back when arrives and tested.
 
A larger port may work better, assuming the lens is sitting in the correct place in the dome. One potential issue the 9-18 has is that the end of the lens does extend while zooming, which will change the port's optics. This may not have been a big deal on earlier m4/3 bodies, but the with the latest ones, the sensors have reached a point where imperfections in the optics are now noticeable.

Alex
 
I have been using the Zen WA 100 EP dome port with my 9-18 and am not overly impressed. The lens is beautiful topside but suffers from what I consider to be unacceptable edge sharpness around 9mm underwater. Most of the posts so far acknowledge this and recommend keeping the most important detail in the centre. As I am hesitant to sell the lens at this stage, can anyone suggest a better port (I am not criticizing the build quality of the Zen, only the results). Will the Olympus ppo-eo4 with an adapter to fit the PtEP11 (em1) give better results (although twice as big). I also have the 8mm panasonic fisheye which I used on my epl2 with the appropriate zen Dome port and was after similar quality ( but not as wide). Just ordered an Athena dome for the 8mm and the em1 and will report back when arrives and tested.


Hello!! try to use a +2 quality diopter on the 9-18mm lens. On Nauticam housings and a similar 4" semi dome (from Nauticam also) shows a lot of improvements on the edges. I even used the +4 diopter and it works well allowing you to focus much closer as well. This was also another limitation underwater. Topside is a great versatile lens but underwater it had the aforementioned issues which stopped me from using it until I tried successfully the diopters.
Also in the SW correction process it helps to provide some lens correction giving it more of a fisheye effect to improve corners.

The 8mm lens on the other hand is a fantastic lens and supper sharp with close focus ability. However it is a bit extreme in some situations.

Hope it helps
Andrea
 
A diopter is needed if the lens can't focus on the virtual image but this is not the case here. The 9-18 lens has poor performance at small aperture ideally you need to shoot at f/4-f/5.6 Max f/8 or sharpness crashes however the dome may not perform well at those f/stops. The zen port is a cut of a larger dome and I don't think a bigger one will help either. The op will have to find settings that work for him bearing in mind the limitations
 
Hello!! try to use a +2 quality diopter on the 9-18mm lens.

Totally agree.

A diopter is needed if the lens can't focus on the virtual image but this is not the case here.

I disagree.

I wasn't happy with my 9-18 until I did some tests with a diopter last winter. The difference was dramatic, and the results are posted on wetpixel.com, with sample pictures.

After that test, I always shoot with a +2 diopter. The +4 is a bit of an overkill for my type of photography, and since I get some pincushion distortion which has to be corrected in post, I don't like the loss of FOV I get with a +4.



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Typos are a feature, not a bug
 
A +2 diopter at those focal lengths might give you better corners but will surely degrade overall quality and also prevent the camera to focus at infinity. Corners are corners nobody looks into that unless they are really poor don't bother
 
Looking at the actual port you are right +2 will still focus the dome is fairly small
however looking at your +4 to be they are blurred in the center or otherwise your images are pretty bad by themselves
the other images are also pretty ugly and f/4 is not really a comparison
The other ones look ok at the edges but there is fringing that the diopter brings. Maybe if you use a high quality achromatic things improve as fringing correction bring back the softness you tried to correct

The image at centre on the pollock shot is soft the 18mm instead is sharp but that would be sharp regardless at 18mm as the image is zoomed in

---------- Post added December 18th, 2014 at 08:15 PM ----------

I would also say that the environment you shoot is not really something you would want to shoot at f/11 so I can see the benefit of using the diopter to bring the aperture to f/5.6 so that you can still shoot at 1/60 and ISO400 and have some ambient light
 
https://www.shearwater.com/products/teric/

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