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

[nudibranco]

did it vignette with the achromat??

 

[Storker]

Hard to say for sure due to the low ambient light, but I didn't notice any vignetting. I could try to take a look at the unprocessed raw files one of the coming days.

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[NautilusCairns]

There seems to be a bit of confusion in this thread between wet diopters screwed onto the front of the port and dry diopters (close up lenses) screwed onto the front of the lens inside the port. Or am I the one being confused?

 

[Storker]

I think it's you. AFAIK you're the first to bring up wet lenses in the discussion. The closeup lenses used to correct corner softness behind a dome are dry, screwed into the filter threads of the camera lens.

 

[Interceptor121]

The 500D is relatively small profile so I do not think it will vignette.
Look forward to the images. It would be interesting to see an uncorrected and corrected image to see how much residual fringing does the diopter bring

 

[kevindale222]

Hi. Interested post. I currently shoot with 9-18mm Oly in olympus housing with zen WA-100 and the corner sharpness has always bugged me. Off to galapagos this year and wanna shoot schooling hammerheads. Is a+2 diopter ideal for the zen some and can you guys recommend the best one to buy. I want the best I can get.

Many thanks in advance.

 

[Storker]

I want the best I can get.

If you do, I can suggest buying a cheap set on eBay, getting in the pool to test different diopters and then buying a quality achromat of the right strength.

If you really want the best you can get, why should you trust a random guy on the 'net?


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[Interceptor121]

Storker how did it go with the canon? To kevindale although the zen port is 100mm you can see that it's a section of s bigger some so it could be possible to use a +3 maybe even +4 before focus at infinity is lost. For galapagos most likely you won't be working at 9mm so corner sharpness around 12-14mm will be less of an issue. Make sure you have strong strobes as the Sharks don't come as close

 

[Storker]

Storker how did it go with the canon?

I think it went very well. Subjectively, I believe I get better sharpness and less CA than with the non-achromatic Vivitar. I've only used the setup once so far, though, so it may be a placebo effect.

It's a bit on the cold (it's below-freezing and the snow is falling) & dark (the sun is less than 10 degrees above the horizon at midday) side around here for UW photography these days, and I haven't had time to take my kit to the pool, so I don't have any systematic tests yet.

---------- Post added January 9th, 2015 at 08:34 AM ----------

most likely you won't be working at 9mm so corner sharpness around 12-14mm will be less of an issue.

Definitely. The mushy corners are a lot less of an issue from ~12mm and upwards.

Make sure you have strong strobes as the Sharks don't come as close

I'm curious if it's practical to carry enough strobe power for distance shots, especially if the ambient light requires smaller apertures. I carried a single Z240 in Ustica, Italy, and that just wasn't enough to light up the more skittish critters that I had to shoot at 18mm.

 

[Interceptor121]

For galapagos take two inon z240 sea and sea YS-d1 or ikelite d160 as the Sharks are far but have white belly so you get a highlight on it. If you have small strobes you either don't make it or it takes forever to recharge if you shoot full power. It s a mix of the two that requires strong strobes and arms wise at least two 8" segments