Housing Flange Distance

[DreiFish]

Trying to gather the distance from the camera lens mount to the front of the camera housings where different extension rings attach. This is for the purposes of calculating the right extension length for various lenses in different manufacturer's housings.

 

I'll kick things off with the Nauticam N120 housings, which I've measured at 58.8mm (let's round to 60mm). If you have one of these housings, could you measure the distance with a ruler please and contribute here?

 

Nauticam N120 - 60mm

Nauticam N100 - 26mm?

Marelux - 43mm?

Seacam - 40mm?

Sea & Sea - ?

Aquatica - ?

Isotta - ?

Ikelite - ?

 

End result will be a spreadsheet like this that I will share here for future reference:

 

[Isaac Szabo]

Isotta is 38mm (for Sony mirrorless at least).

 

Someone with a depth gauge measured N120 Nikon Z for me at 66mm. Is your 58.8mm measurement with a DSLR or mirrorless housing?

[Chris Ross]

The flange distance is different for Canon EF and RF as well as Nikon F and Z mount, the housings are designed so the same lens gear is used for DSLR lenses when mounted on the adapter for mirrorless cameras. 

 

The distances will be different depending on what camera manufacturer the housing is for.

[dentrock]

I just re-measured my Nauticam A7CR rig and it still came out at 28mm.

 

I also measured my Nauticam A7RV and that was 27mm; both using two rulers.

 

I suggest people measure their own rigs... to see if there's any variation. I noticed the tray position is not so precise, so could account for maybe 1mm.

 

Regardless, to make best use of these flange measurements, we will need EP measurements for various lenses (distance from aperture location as viewed from the front, to lens flange); and distance of optical centre behind dome port flange.

 

If you accept that the radius of the Nauticam 140 dome is 70mm, that distance is 7mm (or if you agree with old mate now departed), it's 69mm radius making the variation 6mm.

 

I'll volunteer an estimate of the EP for Sony 20-70 at 77mm, at 20mm (decreasing towards tele end).

 

I wish someone would estimate the EP for their Laowa 10! It's not hard to do! Within a couple of mm will be fine for now.

 

I have EPs for various E mount APS-C lenses, but not much interest in those.

[DreiFish]

On 7/13/2024 at 4:34 PM, Chris Ross said:

The flange distance is different for Canon EF and RF as well as Nikon F and Z mount, the housings are designed so the same lens gear is used for DSLR lenses when mounted on the adapter for mirrorless cameras. 

 

The distances will be different depending on what camera manufacturer the housing is for.

 

Interesting, Chris. I didn't realize they would be different in the same port size (n120). Anyway, my 58.8mm measurement is for the Nauticam Canon RF housings.

[fruehaufsteher2]

Just measured:

 

A7 IV (N100): 26mm

[Aquatica]

On 7/13/2024 at 10:22 AM, DreiFish said:

Trying to gather the distance from the camera lens mount to the front of the camera housings where different extension rings attach. This is for the purposes of calculating the right extension length for various lenses in different manufacturer's housings.

 

I'll kick things off with the Nauticam N120 housings, which I've measured at 58.8mm (let's round to 60mm). If you have one of these housings, could you measure the distance with a ruler please and contribute here?

 

Nauticam N120 - 60mm

Nauticam N100 - 26mm?

Marelux - 43mm?

Seacam - 40mm?

Sea & Sea - ?

Aquatica - ?

Isotta - ?

Ikelite - ?

 

End result will be a spreadsheet like this that I will share here for future reference:

 

I will speak with engineering and get back to you with the camera bayonet to housing flange distances for our verious housings.

[DreiFish]

13 hours ago, Aquatica said:

I will speak with engineering and get back to you with the camera bayonet to housing flange distances for our verious housings.

 

That would be awesome. Hope more manufacturers follow suit.

 

In the meantime, this is the table I've compiled so far:

 

[Isaac Szabo]

On 7/18/2024 at 11:36 PM, DreiFish said:

 

That would be awesome. Hope more manufacturers follow suit.

 

In the meantime, this is the table I've compiled so far:

 

 

Can I ask where you found 43mm for Marelux? And what camera system that is for? I'm trying to confirm the distance for Marelux Sony full frame mirrorless. One person measured their housing for me and came up with 39.1mm. It would be great if anyone here can confirm that. 

[Craine]

On 7/19/2024 at 12:36 AM, DreiFish said:

 

That would be awesome. Hope more manufacturers follow suit.

 

In the meantime, this is the table I've compiled so far:

 

I measured my Nauticam a6700 (N85) at 11.75mm from camera flange to housing flange. 
 

I’ve got a few ports/adapter handy to measure if the desire is there. Now I need to go figure out the optical center of the Zen DP170 (N120 mount), and I will measure the EP of various FL of my Sigma 10-18. Yes it’s all APS-C which is blasphemy to some, but at least the measurements will be available for someone who wants them. 

[boduoguo]

On 1/10/2025 at 9:28 PM, Craine said:

I measured my Nauticam a6700 (N85) at 11.75mm from camera flange to housing flange. 
 

I’ve got a few ports/adapter handy to measure if the desire is there. Now I need to go figure out the optical center of the Zen DP170 (N120 mount), and I will measure the EP of various FL of my Sigma 10-18. Yes it’s all APS-C which is blasphemy to some, but at least the measurements will be available for someone who wants them. 

I hope to share the nauticamA6700+SIGMA10-18 part once I have the results, I'm considering other options besides the 18-50+WWL.😀

[WindWaternWaves]

Just measured my Seacams

 

Sony A1 - 38.5mm

Nikon D850 - 39.5mm

Nikon D200 - 39.5mm

[Adventurer]

On 7/13/2024 at 4:22 PM, DreiFish said:

 

Marelux - 43mm?

 

I am a huge fan of your spreadsheets works @DreiFish but the MARELUX value looks wrong to me. I think I measured 51mm could someone i.e. @Phil Rudin confirm this? I think sensor to bayonet distance in Marelux Canon housings is exactly 70mm.

[Phil Rudin]

The chart is I believe a measurement from the lens mount (not sensor) to the front opening (outside) of the housing. I don’t have a very accurate ruler but with the Sony housings it appears to be very close to the 43mm stated for Marelux on the chart. This has remained constant across at least seven MX housings I have used for several Sony cameras. I have handled several housings for Canon and Nikon at DEMA and all appeared to have the same distances. 

[Adventurer]

To me this looks clearly indisputable like 51 mm (metric).

 

I have attached two images to see if we are both talking about the same distance.

 

The sensor plane is 19mm more towards the camera, so from sensor to marelux bayonet it is 19+51 = 70 mm

 

Any thoughts or comments ?

 

 

Edited February 6 by Adventurer
layouted

[Adventurer]

On 2/1/2025 at 7:15 AM, WindWaternWaves said:

Just measured my Seacams

 

Sony A1 - 38.5mm

Nikon D850 - 39.5mm

Nikon D200 - 39.5mm

 

The above reads a little more solid than the other mm values exchanged here.
 

I‘d like to put my finger in a wound with salt:

 

If the flange distances of the underwater housing manufacturers are really displaying substantial variances for one camera brand mount (i.e. Canon RF portchart, Sony E Mount Port Chart, Nikon Z Mount Chart) they have been giving their customers really bad advice and dismal optical configurations for years.
 

A lot of port charts have to be rewritten then,… phew. 🤐

 

This struck me after sleeping one night over this sensitive topic. 💣💥

Edited February 7 by Adventurer
spelling of the word finger

[Phil Rudin]

Edited February 7 by Phil Rudin

[Adventurer]

That looks like solid 43mm for MARELUX SONY flange, Phil.

[Phil Rudin]

I will start over with this since the text and photos disappeared. This is a lot of do about not much to me. As you can see in both photos my measurement is identical +/- very little. First photo is the Marelux Sony A7R V housing and the second is the Sony A7C II/R housing. 

 

The Canon cameras are bigger and so is the housing, as a result the camera sits further back inside the housing. The only lens the Canon and Sony systems have in common is the Canon 8-15mm fisheye used in both Marelux housings with an adapter. The Canon camera needs a 30mm extension for 140 & 230mm dome ports in the Marelux housing while the Sony cameras use a 40mm extension for 140 & 230mm ports. The 10mm difference in extensions seems correct given the difference in flange distance.  

[Isaac Szabo]

I have gotten confirmation from a Marelux engineer that the distance for Sony is 39mm (the 4mm disparity is very significant for what I do).

[Chris Ross]

On 2/7/2025 at 7:11 PM, Adventurer said:

I‘d like to put my finger in a wound with salt:

 

If the flange distances of the underwater housing manufacturers are really displaying substantial variances for one camera brand mount (i.e. Canon RF portchart, Sony E Mount Port Chart, Nikon Z Mount Chart) they have been giving their customers really bad advice and dismal optical configurations for years.
 

A lot of port charts have to be rewritten then,… phew. 🤐

 

This struck me after sleeping one night over this sensitive topic. 💣💥

There are lots of reasons why the flange distance might vary between brands, it's only important to be consistent within a brand or more specifically a lens mount such as Canon EF, Nikon Z etc.  For example Nauticam Canon RF housings place the camera back further in the housing such that the RF-EF converter if where the flange of an EF mount camera would be relative to the flange.  This is important as it means the EF port chart applies to EF lenses used on the RF-EF converter and the same zoom gear is used.  This means that the upgrade path is easier for a Canon EF user to upgrade to RF.  Initially they can bring across their EF lenses, zoom gears, ports and extensions with no additional investment.

 

Nauticam have done the same for Nikon Z mount housings.  Other manufacturers may have done things differently. 

 

In the end it doesn't matter if they move the flange distance around between different lens mounts as they can compensate for it with different extensions.  They probably start with the shortest fisheye lenses so they can be used without extension in the small dome ports.   For example the Panasonic 8mm fisheye uses no extension on m43 housings, on Canon EF, the Sigma 10mm fisheye and Canon 15mm fisheye use no extension etc.  The shortest lens they design for is probably different in each lens mount.  They also take into account where they place the housing zoom/focus gear drive in the housing and the need to mate up with that.

[Adventurer]

11 hours ago, Isaac Szabo said:

I have gotten confirmation from a Marelux engineer that the distance for Sony is 39mm (the 4mm disparity is very significant for what I do).

Well that does not match Phil's picture posted above. And while it makes sense, that diffent camera brands (Nikon Z, Sony E, Canon RF) have different flange to housing distances and therefore different port charts, it would not make too much sense, if Sony E Mount Camera Model X has different flange distance than model Y and Z. In that case camera X, Y and Z would need new different port charts.

 

I think the source of 4mm gap: 43mm (measured by Phil) versus 39.1 (measured by @Isaac Szabo customer and confirmed by Marelux engineering) might have a more simple explanation.

 

 

@Phil Rudin, could you be so kind and have a look if there is a blank space at the beginning of your ruler, that you have put onto the cameras flange? This is something we could not see in the two images provided.

[Phil Rudin]

My plastic ruler is less than accurate and has a 6mm blank space but I took that into consideration when I made the posted measurements. What is most important to me is that I currently have three different Marelux housings in house for Sony A1, A7R V and A7C II/R and the cameras to match. Using my measuring device all three housings are the same +/- 0.2/3mm.  

[Isaac Szabo]

22 hours ago, Adventurer said:

Well that does not match Phil's picture posted above.

 

Using two rulers like that is not a very accurate method. It's probably fine if you want an estimate within 5mm or so but not if you need high accuracy. The ruler laying flat across the housing is certainly not rigid and unlikely to be flat. Turning the ruler on its side would at least make it fairly rigid. Also, viewing the ruler from an angle that is not perfectly perpendicular will result in a reading error. Another source of error is if the vertical ruler is not perfectly perpendicular to the camera mount (this can't be seen in these photos). And like you said, cheap rulers are not guaranteed to give very accurate readings, especially from the end which is often not perfectly aligned with the zero mark.

 

A more accurate method is to place a precision depth gauge on a flat, rigid, metal object spanning the housing opening (and then subtract the thickness of the metal object). 

 

I don't say these things to disparage Phil. I really appreciate his effort, and his result would probably suffice for help with choosing a proper extension. But for what I do with the Nikonos 13mm (I'm currently making a Marelux version) a 4mm error means vignetting in one direction or the inner lens crashing into the dome in the other direction. 

It's also possible that Phil's housings have different dimensions than the housings of my client and the Marelux engineer, though that would be pretty concerning. And I should note that my client's housing is the same as one of Phil's (Sony A1), and he used the method I described above.

Anyway, thanks again to Phil and everyone else here for taking the time to share this helpful information.

Edited Tuesday at 11:50 AM by Isaac Szabo

[Adventurer]

6 hours ago, Isaac Szabo said:

a 4mm error means vignetting in one direction or the inner lens crashing into the dome in the other direction. 

I am totally with you, Isaac. But as the original intention of this thread was to build an excel sheet that readers might take for granted I would suggest to abandon that mission.

The case illustrates:

 

You simply do not know how accurate your volunteering data donors are at measuring and reading the results.