Olympus 8mm Fisheye with larger dome via N85 - N120 converter

Thank you very much for the replys and hints to the reviews.

 

What's your reason for upgrading? I have the 8mm Pany used with the Zen 100mm dome and It's sharp except for the very corners. Here's an example:

I love my 4.33" with Pana 8mm since it is so small and light. Very easy to travel with, especially when I am also taking my dive gear, tripod, drone, etc. and it is possible to get very close.

However, I finally would like to take great split pictures. The 4.33" is just to small for it as soon as you have a few ripples / waves. Of course bigger domes are better for split pictures due to more space between lens and water. But changing to another lens (Pana 8mm-> Oly 8mm) to be able to use the large dome (Zen 170mm) is a big investment, which at the same time makes it harder to travel with.

Simply upgrading to the Nauticam 140mm which can be used with my Pana 8mm is definitely the cheaper and lighter option. But will the dome diameter upgrade be big enough for my taste, I don't know since I never tried a large dome.

Going to the back issues in uwpmag.com again, a free PDF download I have the following reviews. Issue #64 Pana 8mm N-4.33, #97 Oly-8mm with N-140.

Thank you for the very informative reviews in the magazines. Unfortunately there is only one sentence regarding split pictures "I found the Nauticam 140 mm port worked well for split images in relatively calm water, using f/8 and above." with the Oly 8mm + Nauticam 140mm + extension ring.

By judging from you model pictures above it indeed looks pretty good (with the 12mm and so presumably even better with the 8mm) at least in very calm conditions.

I have to think about it, but will probably go with the 140mm dome due to its overall benefits compare to 'just' easier split pictures. Thank you very much everyone

I have been following this thread, very interesting observations here!

I own a EM5 MarkII with Olympus housing and the Inon dome for fisheye (around 5.2 inches). Someone has experience whether the fisheye lens would perform better in a bigger dome (eg 170mm)? Im considering changing as I can fit also my 7-14...

Thanks again for all the info!

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In general if the dome is positioned correctly there is not an advantage for a larger dome with fisheye lenses. The large dome helps on rectilinear lenses as the radius of the virtual image is larger and is further away so the lens has a better chance of bringing the corners into focus. Rectilinear lenses are designed to focus on a flat image plane. Fisheye lenses on the other hand are designed with a 180° field of view and are designed to focus on a curved image - you can't achieve a 180 ° field of view of a flat surface, that together with their huge depth of field allows them to work with small domes as long as they are placed correctly in the dome.

A potential issue with larger domes is that many are not full hemispheres - an advantage for rectilinear lenses because the radius of curvature is larger than it otherwise would be, but you still need to place the lens nodal point at the centre of curvature of the dome which can cause vignetting. You place the lens further forward to stop the vignetting but the image quality is not as good as it might otherwise be. It's difficult though to find much information on what this actually means for image quality or even find an example posted online.

Which 7-14 are you proposing to use? - I believe the 7-14mm olympus lens does not fit the EM-5 II olympus housing as it uses the smaller PEN port system.

ChrisRoss, extremely clear explanation. Actually I got a used PTEP14 so Im planning to get my EM1 Mark II underwater and expand a little bit my options. I have been shooting mostly Fisheye and Macro for the last 3 years and start feeling a bit limited with the Fish Eye.

I am thinking that with a 170mm+ dome in the PTEP14, I can fit both the Olympus 7-14 as well as the 12-40 (I would love to have the versatility of the 12-40 with zoom gear...).

There are still a couple of the aspects where Ive found little info. One is regarding performance of 12-40 in higher focal lengths behind a dome. The other one is regarding semi-domes performance, as AoI officially recommends a semi-dome for the 12-40.

Thanks again for the very relevant input.

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ChrisRoss, extremely clear explanation. Actually I got a used PTEP14 so Im planning to get my EM1 Mark II underwater and expand a little bit my options. I have been shooting mostly Fisheye and Macro for the last 3 years and start feeling a bit limited with the Fish Eye.

I am thinking that with a 170mm+ dome in the PTEP14, I can fit both the Olympus 7-14 as well as the 12-40 (I would love to have the versatility of the 12-40 with zoom gear...).

There are still a couple of the aspects where Ive found little info. One is regarding performance of 12-40 in higher focal lengths behind a dome. The other one is regarding semi-domes performance, as AoI officially recommends a semi-dome for the 12-40.

Thanks again for the very relevant input.

Sent from my SM-N960F using Tapatalk

ChrisRoss, extremely clear explanation. Actually I got a used PTEP14 so Im planning to get my EM1 Mark II underwater and expand a little bit my options. I have been shooting mostly Fisheye and Macro for the last 3 years and start feeling a bit limited with the Fish Eye.

 

I am thinking that with a 170mm+ dome in the PTEP14, I can fit both the Olympus 7-14 as well as the 12-40 (I would love to have the versatility of the 12-40 with zoom gear...).

 

There are still a couple of the aspects where Ive found little info. One is regarding performance of 12-40 in higher focal lengths behind a dome. The other one is regarding semi-domes performance, as AoI officially recommends a semi-dome for the 12-40.

 

Thanks again for the very relevant input.

 

Sent from my SM-N960F using Tapatalk

ChrisRoss, extremely clear explanation. Actually I got a used PTEP14 so Im planning to get my EM1 Mark II underwater and expand a little bit my options. I have been shooting mostly Fisheye and Macro for the last 3 years and start feeling a bit limited with the Fish Eye.

 

I am thinking that with a 170mm+ dome in the PTEP14, I can fit both the Olympus 7-14 as well as the 12-40 (I would love to have the versatility of the 12-40 with zoom gear...).

 

There are still a couple of the aspects where Ive found little info. One is regarding performance of 12-40 in higher focal lengths behind a dome. The other one is regarding semi-domes performance, as AoI officially recommends a semi-dome for the 12-40.

 

Thanks again for the very relevant input.

 

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The EM-1 II is great UW, AF is a big improvement over the EM-5 II, C-AF plus tracking works very well. The 12-40 is very good at all focal lengths some examples:

http://homepages.ihug.com.au/~chrisx2/images/GiantCuttlefish20.jpg taken at 12mm

http://homepages.ihug.com.au/~chrisx2/images/Wobbegong4.jpg taken at 40mm both near full frame just a slight crop for composition. I use it behind the Zen 170mm dome

http://homepages.ihug.com.au/~chrisx2/images/BlackEyeGoby.jpg this is very close at 40mm

There are a number of dome options for the PT-EP14 including Olympus's own dome, this is the system chart: https://asia.olympus-imaging.com/content/000085635.pdf

Interesting that you mention about CAF+Tracking, I only tried intensively CAF.

Some pics with the fisheye also below!

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