Hi All,

Looking for some advice on modifying a Zen dome.

I have a 100mm (4") Zen DP-100-N120N dome which I use for CFWA with a Nikon 10.5mm fisheye.

I'm planning to move to Micro 4/3 (OM1 Mk. II in Nautcam) and would like to bring the dome with me. Nauticam make a couple of N85 to N120 adaptors but they all seem to be too deep to use with the Olympus 8mm lens I am planning.

The base of the dome seems to be held in place with a series of allen head bolts so presumably it just unscrews.

Does anyone know if you can buy a replacement base doe the dome to convert it to a DP-100-N85 that I can use with the Nautical extension ring or is there another port adaptor out there that would work?

Appreciate the advice.

I suspect you would need to use a custom made adapter. The 10.5mm is not on the Nauticam port charts any longer, but I seem to recall it used no extension and looking at the N120N dome it appears it uses no extension either. The Port charts specify a 17mm extension for the Olympus fisheye , so it seems like there is enough room to make an adapter. This means you would need a 17mm N85-N120 adapter which is not made.

As for buying the metal only part of the n85 DP100 dome I would suggest messaging Reef photo to see if they have that as an option. This is what you would need to buy because as far as I can see the aluminium part of the N85-DP100 dome is machined from a single piece of aluminium. It might work out cheaper to pickup a second hand dome is you could find one?

An alternative might be to use a Tokina 10-17mm, you can buy a N85-N120 adapter for that to use on m43 with the Metabones speed booster. You would need the lens plus N120 zoom gear the appropriate N85-N120 adapter and possibly an extension ring to use with your dome. There are probably various options to allow you to use your dome in that setup. There are people on here using that combo including Wolfgang( @Architeuthis ). You could put up another post seeking experience with that combination and the part list if it was of interest to you.

The advice from Cris is very good. Tokina 10-17mm or Canon 8-15mm. Same IQ compared to Zuiko 8mm, but much better versatility. It comes, however, at a cost (I believe it is worth every cent), maybe the price is comparable (the speedbooster is not cheap), but you can count together the current price of items by yourself...

Another possibility is, that you do not need an extension as short as 17mm and, in practice, it could be somewhat longer. I was using e.g., the Zuiko 8mm with the 34.7mm N85/N120 adapter, as well as with a custom made 30mm N85/N120 adapter with the Nauticam 140mm domeport, with very good results (the extension recommended by Nauticam is 30mm). Theoretically there should be no difference between 140mm and 100mm domeports regarding extensions, since both are hemispheres (but there may be a difference in practice)...

Wolfgang

Thanks @Chris Ross @Architeuthis

That all looks like good advice, I'll mock it up when the new kit arrives and see what depth of adapter is needed, the 8mm Zuiko does look to be quite a physically long lens compared to other fisheye options (including the Panasonic Lumix 8mm), so it may be that one of the stock N85 to N120 adapters will work.

16 hours ago, Dolphin said:

Thanks @Chris Ross @Architeuthis

That all looks like good advice, I'll mock it up when the new kit arrives and see what depth of adapter is needed, the 8mm Zuiko does look to be quite a physically long lens compared to other fisheye options (including the Panasonic Lumix 8mm), so it may be that one of the stock N85 to N120 adapters will work.

I think the risk with the longer adapters is vignetting due to the smaller diameter dome shade, compared to the 140mm dome. . Easily checked out on land of course, though the N85-N120 adapters are quite expensive these days. If you don't want to go with the 10-17 or 8-15 it may end up being cheaper to buy an N85 100mm dome, particularly if you could source one second hand.

3 hours ago, Chris Ross said:

If you don't want to go with the 10-17 or 8-15 it may end up being cheaper to buy an N85 100mm dome, particularly if you could source one second hand.

Best solution when staying with Zuiko 8mm ... 👍

And when you counterbalance the gain from selling the N120 version, it will be little money in summary...