Tips to avoid blurry edges ?

20mm AND a 26mm? Don't you need Isn't it JUST a 20mm? That's the way I read this.

For Subal the domes need a 20mm EXR with the Nikkor 8-15

@TimG

With the Z series, you need an adaptor that allows you to use F mount lenses (like the 8-15mm).
This is the 26mm element (for the FTZ adaptor)
It is not (in strict terms) an extension, but an adaptor that allows the use of F mount lenses.

Adam

Oh right, thanks Adam. Understood. I knew about the FTZ and can see you may well not call that an extension. 

And this is what Isotta suggested just now:

Hi Ido,

if you want to stay with the 4,5” port you can add an 20 mm extension ring (with this you should reduce the blurry edges)

The disadvantage is that if you want to do macro/wide you will find yourself further away from the subject so you will have less macro effect

On 12/9/2021 at 2:38 AM, adamhanlon said:

@TimG

With the Z series, you need an adaptor that allows you to use F mount lenses (like the 8-15mm).
This is the 26mm element (for the FTZ adaptor)
It is not (in strict terms) an extension, but an adaptor that allows the use of F mount lenses.

Adam

Hey Adam. After reading this I am question my most recent purchase. I have an EOS R5 and I just got the 8-15 fisheye with a 1.4x kenko teleconverter and a 4" zen dome. While this is largely for CFWA, am I also going to suffer from super soft corners when trying to shoot reefscapes?

On 12/10/2021 at 12:24 AM, ido said:

And this is what Isotta suggested just now:

 

Hi Ido,

if you want to stay with the 4,5” port you can add an 20 mm extension ring (with this you should reduce the blurry edges)

The disadvantage is that if you want to do macro/wide you will find yourself further away from the subject so you will have less macro effect

  

I would certainly try the 20mm extension before you buy a new dome.  It's a bit of a no regrets purchase as you would need the 20mm extension for a 6.5"dome.  That together with stopping down some more might be enough??

Thanks. I will try it as well

@shakuiel

Hi,

Sadly the answer is yes! It should work well for CFWA, but will be limited for reefscapes. Let me know how you get on with the Kenko converter...

The short answer with any port is that the bigger the port, the better the corners. The bigger the sensor (and arguably the higher its resolution) the more pronounced this is.

Yes, you can stop up, but this will inevitably result in compromises in exposure settings. 

I'll borrow this thread for a while. I use Nikon Z6/7 in a Sea & Sea housing. I also have the Nikon 8-15 fisheye, used on FTZ adapter of course. Furthermore I have the Zen 230 mm dome and a 40 mm extension. In a thread here last autumn we reached the conclusion that I should probably use a 20 mm extension with the fisheye and the 230 mm dome (so that's not the question here).

Before hitting the purchase button I thought I'd see if there are other alternatives that may be better. Specifically, Sea & Sea makes the Optical Dome Port ll 100 L (link) which is "Designed exclusively for (...) Nikon AF-S Fisheye Nikkor 8-15mm F3.5-4.5 E ED".

While more expensive than buying just an extension ring this would be a more nimble solution in close quarters. But... is there any reason to believe that this is optically anything special, or is the "designed exclusively" limited to extension length?

I believe the “exclusive” bit is just the built in extension. Saga do the same thing.

then there is the whole mini dome / big dome debate.

8 hours ago, horvendile said:

I'll borrow this thread for a while. I use Nikon Z6/7 in a Sea & Sea housing. I also have the Nikon 8-15 fisheye, used on FTZ adapter of course. Furthermore I have the Zen 230 mm dome and a 40 mm extension. In a thread here last autumn we reached the conclusion that I should probably use a 20 mm extension with the fisheye and the 230 mm dome (so that's not the question here).

Before hitting the purchase button I thought I'd see if there are other alternatives that may be better. Specifically, Sea & Sea makes the Optical Dome Port ll 100 L (link) which is "Designed exclusively for (...) Nikon AF-S Fisheye Nikkor 8-15mm F3.5-4.5 E ED".

While more expensive than buying just an extension ring this would be a more nimble solution in close quarters. But... is there any reason to believe that this is optically anything special, or is the "designed exclusively" limited to extension length?

It will just be the extension, it's a trade off of corner quality for the ability to get in close.  A 230mm dome will make it hard to do any sort of CFWA.

Thanks both of you. Yeah, I guess I will have to choose between good edges (€300) and CFWA (€1000). Right now it will probably be the former, if not else for economic reasons.

14 hours ago, horvendile said:

Thanks both of you. Yeah, I guess I will have to choose between good edges (€300) and CFWA (€1000). Right now it will probably be the former, if not else for economic reasons.

Your other option would be a Nauticam 140mm dome as a more all round solution, you can just change the bayonet ring to a Sea & Sea one to use on your housing.

14 hours ago, ChrisRoss said:

Your other option would be a Nauticam 140mm dome as a more all round solution, you can just change the bayonet ring to a Sea & Sea one to use on your housing.

Another option is what I did (and not tested yet):

Isotta 6.5 dome with 20cm extension (It should be compatible with Sea&Sea)

Late reply, sorry.

There's also the Sea&Sea native 165 mm port. Speaking of changing bayonet ring though, is that something which works as a general solution? Suppose that I would want eg the Nauticam WACP or MWL-1. Are those possible to adapt for Sea&Sea use?

4 hours ago, horvendile said:

Late reply, sorry.

There's also the Sea&Sea native 165 mm port. Speaking of changing bayonet ring though, is that something which works as a general solution? Suppose that I would want eg the Nauticam WACP or MWL-1. Are those possible to adapt for Sea&Sea use?

Yes, any Nauticam port with a removable bayonet ring, you can replace it with a S&S bayonet ring (in N120 size).  The MWL-1 is different though it attaches to a flat port, though of course if the Nauticam flat port used a removable bayonet ring you could use that port on S&S.

On 12/11/2021 at 4:03 AM, adamhanlon said:

@shakuiel

Hi,

Sadly the answer is yes! It should work well for CFWA, but will be limited for reefscapes. Let me know how you get on with the Kenko converter...

The short answer with any port is that the bigger the port, the better the corners. The bigger the sensor (and arguably the higher its resolution) the more pronounced this is.

Yes, you can stop up, but this will inevitably result in compromises in exposure settings. 

Just did my first two days of diving with my 4" minidome and 8-15mm fisheye on the Canon R5. Buying a bigger dome ASAP, corners are MUSH. I saw an old post of you recommending a 180mm glass, does that still stand true?

22 hours ago, shakuiel said:

Just did my first two days of diving with my 4" minidome and 8-15mm fisheye on the Canon R5. Buying a bigger dome ASAP, corners are MUSH. I saw an old post of you recommending a 180mm glass, does that still stand true?

The recommendation will depend a little on which housing system you are using as dome sizes vary a little among vendors.  You should also confirm you are using the recommended extension and are stopping down enough all of which will make some difference, I ask as while corners may be bad with 4"domes and a fisheye on full frame, MUSH sounds like the potential for other issues compounding the problem.

26 minutes ago, ChrisRoss said:

The recommendation will depend a little on which housing system you are using as dome sizes vary a little among vendors.  You should also confirm you are using the recommended extension and are stopping down enough all of which will make some difference, I ask as while corners may be bad with 4"domes and a fisheye on full frame, MUSH sounds like the potential for other issues compounding the problem.

 

Mush is probably dramatic, I have been shooting wide angle for like two days so I don't really know much difference from bad to extreme. Spoke with Kevin from ReefPhoto and send him some sample pictures and I'm gonna upgrade to the 140mm dome. I was using the right extension (no extension) and was at F11 with the issues

1 hour ago, shakuiel said:

Mush is probably dramatic, I have been shooting wide angle for like two days so I don't really know much difference from bad to extreme. Spoke with Kevin from ReefPhoto and send him some sample pictures and I'm gonna upgrade to the 140mm dome. I was using the right extension (no extension) and was at F11 with the issues

sounds like you are on Nauticam, the 140mm dome is Nauticam's recommendation as most optimised for the 8-15mm and uses a 30mm extension.  Sounds like you were on the Zen 4"dome with the extension built in.

I found when I first started using fisheye lenses I need to watch out for parts of reef that were much closer than the subject so were on the edge of the depth of field available - most pronounced on wall dives It's not always immediately obvious when first looking at the photos until I looked closely at one where the LHS of frame was very close and it also had reef detail in the opposite corner that was much sharper.