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

[kevindale222]

Storker I ask as you seem to have extensive research yourself on the best options. I have read I think your previous peices on galapagos maybe wet pixel. I'm afraid I will only be taking my inon s2000's whixh I don't think will be powerful enough. But all I have working at moment. Hopefully will be enough. . Have you tried differnt set up with the 9-18mm and zen dome with diopers interceptor??

 

[Storker]

It s a mix of the two that requires strong strobes and arms wise at least two 8" segments

Wow. You don't settle for compromises, do you?

I'm more prone to accept compromises. Two 8" segments are just too much for me to handle; the rig gets too cumbersome. I've settled for 5"+7" segments on my rig, and if the viz is good, that works quite well for me.

Storker I ask as you seem to have extensive research yourself on the best options. I have read I think your previous peices on galapagos maybe wet pixel. I'm afraid I will only be taking my inon s2000's whixh I don't think will be powerful enough.

I think you're confusing me with someone else. I've never been to Galapagos.

I'm afraid I will only be taking my inon s2000's whixh I don't think will be powerful enough.

I agree with Interceptor121: It's probably not enough; IIRC one Z240 gives about the same light output as two S2000s. OTOH, you can't lose by trying. Just be prepared to shoot ambient and do some post-processing. And try to shot at the largest aperture your sync speed allows; that will maximize the ratio of strobe vs ambient.

 

[kevindale222]

Interceptor I have sent you a PM.

 

[Nickbell]

Thanks Nudibranco and Storker for your advice. Just spent an hour in the pool (28C in water and 30C ambient. Sorry Storker couldn't resist) with new Canon 500D (their designation for a +2 diopter) on my 9-18 Olympus, Em1 and Zen WA100 dome. Was never happy with lens at low apertures @ 9mm. Did some comprehensive comparisons with and without filter from f5.6 to f22 at 9 mm. Will do some more tests later on to see how it performs at 18mm.
The Canon 500d is a high quality multicoated 2 element 52 mm filter that does not vignette @ 9mm. I am pleased to say that there are NO additional chromatic aberrations on the corners at all apertures tested. In addition, there is no loss of image quality in the centre when viewed at 100%. In fact there seamed to be a very slight increase in centre sharpness up to f11. The only negative is that the filter slightly decreases the angle of view. On land it gives the 9mm an equivalent view to the 10.5mm setting. I am not sure if this also contributes to the dramatic increases in corner sharpness I am about to describe, as the lens has always performed better at the longer focal lengths. As mentioned previously corner sharpness has always been a problem at wide apertures. The +2diopter did not entirely remove the softness in the extreme corners, but it did help considerably across the majority of the frame. I was able to achieve almost the same corner sharpness at F5.6 with the filter as I previously achieved at F11 without the filter. For me, I am now comfortable using the lens at f5.6 & f8 and resorting to F11 when sharpness is required across most of the frame. At f16 and f22 there is no increase in sharpness on the corners as the whole image becomes softer due to diffraction. So far it appears to be almost a two stop increase in corner sharpness at 9mm. If it does not adversely affect the 18 mm end then I will be leaving it on all the time. Further testing will tell. At US$57.00 from Japan, it was money well spent.

 

[Storker]

Cool.

The diopter gives some pincushion distortion as well, but that's quite easy to fix in post.

28C in water and 30C ambient. Sorry Storker couldn't resist

Yeah, I can imagine that you couldnt. Bastid.

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[Interceptor121]

Testing on land the field of view is not representative as the lens will not focus anymore at infinity. Also focal length gets shorter not longer so the real proof is in water

 

[Storker]

The pincushion correction in post steals some FOV, though

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[Interceptor121]

A +2 is not too bad to the point you could leave the distortion as is. If you have a 4/5/10 then of course it gets bad but in my 1/2 shots with the wetmate I couldn't really make much of it even shooting a ruler

 

[Storker]

A +2 is not too bad to the point you could leave the distortion as is.

Yep, sometime that works just fine. Other times, with other subjects, not so much. It's always a judgment call as to whether to correct or not.

 

[kevindale222]

How did you find the canon diopter @ 18mm area. Is the dipoter only Advantagous at the 9mm end? I read you were testing to see if diopter can be left on for whole focal range. Any findings??