Does anyone have the distance for the A7 camera flange to the port seat on the NA-A7 housing.

I am trying to convert the NA-A7 Nikonos adapter for the Fuji Nauticam housing.

I need to figure how much I need to reduce the flange distance of the Adaprter.

The lens work but I need to reduce the flange distance to get it to focus at infinity.

It will focus with the adapter but acts like an extension. 

This does not make much sense as the lens is already 20mm so you would be looking at best at 30mm?

I am assuming APSC as medium would vignette

 

The difference between the Fuji Mount and the Sony E is .3mm. 18 on the Sony, 17.7 on Fuji.  Nikonos focal flange is 28mm.

If the adapter to sensor distance is the same from the Sony to the Fuji, I would have to shave .3mm. I do not have the Sony camera and housing available to measure. Reluctant to put a mic directly on the Fuji  sensor to measure.

3 minutes ago, Tobyone said:

The difference between the Fuji Mount and the Sony E is .3mm. 18 on the Sony, 17.7 on Fuji.  Nikonos focal flange is 28mm.

If the adapter to sensor distance is the same from the Sony to the Fuji, I would have to shave .3mm. I do not have the Sony camera and housing available to measure. Reluctant to put a mic directly on the Fuji  sensor to measure.

The adapter doesn’t touch the sensor it is just a piece of rubber that goes on the mount 

the nikonos 15mm is indeed 20mm

with apsc crop this is 30mm

you can shoot many lenses that work well at 30mm

On my Nauticam A7II housing the distance is 25.97mm. 

 

However, it should be noted that in at least some cases the Nauticam adapter does not provide infinity focus with some of the Nikonos lenses. It could be that the Nauticam adapter is a tad too thick or that some of the Nauticam housings hold the camera a tad too far from the port mount. Either way some users have had to modify their housings to bring the camera a tad closer to the adapter in order to achieve infinity focus. So to ensure success the first time around you might make your adapter slightly thinner (perhaps 0.5mm) than the Nauticam dimensions indicate. Here's a link to a wetpixel thread on the subject. 

Edited April 30, 20241 yr by Isaac Szabo

15 hours ago, Isaac Szabo said:

On my Nauticam A7II housing the distance is 25.97mm. 

 

However, it should be noted that in at least some cases the Nauticam adapter does not provide infinity focus with some of the Nikonos lenses. It could be that the Nauticam adapter is a tad too thick or that some of the Nauticam housings hold the camera a tad too far from the port mount. Either way some users have had to modify their housings to bring the camera a tad closer to the adapter in order to achieve infinity focus. So to ensure success the first time around you might make your adapter slightly thinner (perhaps 0.5mm) than the Nauticam dimensions indicate. Here's a link to a wetpixel thread on the subject. 

Thanks Issac,

I will  do some calculations and see if I can match the two cameras sensor distances

Where the camera flange sits inside the housing was changed going from the a7 to the a7ii (and newer).

I would suggest looking at both port charts and taking into account the difference on top of Isaac’s measurements.

12 hours ago, Robin.snapshots said:

Where the camera flange sits inside the housing was changed going from the a7 to the a7ii (and newer).

I would suggest looking at both port charts and taking into account the difference on top of Isaac’s measurements.

The new A7III and post are at 27mm

this is housing to mount 

the sensor is 18mm below

to make it work you would need the two deltas to compare

again what would anyone do with 30mm equivalent is a mystery to me..

Edited May 2, 20241 yr by Interceptor121

I measured the Nikonos 2 flange which is 32.18 mm.from the lens mount base to the film plate. Being careful not to push the spring plate tensioners back. I measured the distance from the mounted Nikonos adapter to the Fuji XT-3 front of sensor protection glass(There is no bayer filter in Fuji) in the Nautical housing. The distance was 31mm. I have yet to get a depth of this glass to the sensor. Could be .5-2 mm in thickness. So it look like I can shave 1.5 mm and get the lens to focus near infinity.I will test by sliding back the camera on the plate in the housing top side. I have an 80 mm Nikonos Lens to test focus. Before I start removing metal form the adapter.

I made some adapters to test Nikonos lenses on Sony mirrorless 3-4 years ago. It's hard for me to recall all the details, but looking back at some of my notes, I think the adapter thickness I settled on was around 14-15mm. Sony flange distance is 18mm, which means my Nikonos flange distance was around 32-33mm, which is very close to your 32.18mm measurement. 

 

The X-T3 has 2 filters in front of the sensor which together total around 2mm. Below that is the sensor cover glass of perhaps 1mm (just a guess) and a small gap until the photosites. So I'd guess the total distance from the outermost glass to the photosites is more than 3mm, but it's probably not going to be possible to get the exact number since measuring the cover glass thickness and the gap underneath would require destroying the sensor. 

 

Rather than measure from the mounted Nikonos adapter to the outermost sensor filter, I would recommend measuring from the mounted Nikonos adapter to the camera's lens mount. Then add to that the camera's flange distance of 17.7mm and see how far off it is from 32.18mm. I think that should give you a pretty good idea of how much you need to remove from the adapter. It does sound like it will probably be around 1.5-2mm. 

 

How are you going to remove thickness from the Nauticam adapter? Can you just do it in steps (perhaps 0.5mm) and test each time until you achieve infinity focus?

After all the calculations, especially considering the glass in front of sensor, I think I am abandoning this project. I would probably have to machine at least 3 mm off to get close to infinity focus, leaving a too thin of a lip. Also considering the Fuji crop factor,I would not be getting the moderate(underwater)wide angle option the 15mm presents.  I will just use for macro with the 80mm and maybe see how the 15 does with closeups.

Thanks for everyones input.

Edited May 5, 20241 yr by Tobyone

Hello Tobyone,

I'm curious to know how the tests went?
I am interested in this topic, since I also own a Fuji X-t3 / Nauticam equipment, and I may have access to some Nikonos optics.

Any feedback regarding the quality of the files obtained and the ease of use of the lenses underwater would be wellcome.

All the best.