M43 prime lens with dome port?

Can anyone shed some light on using prime lenses with dome ports? I have an Olympus M5iii with the panasonic 8mm fisheye and a 4 inch dome port. I'm using the AOI housing.

I'm wondering what other lenses I can put behind the dome. I know some people have had good experience with 25mm lenses (50mm ff equivalent) and I'm looking at the olympus 17mm f1.8 for above water so I'm wondering if I can use that behind my dome.

How does one know what lenses will work without getting one in their hands and trying it out? I'm also wondering what length extension I would need if I wanted to put my 12-45mm f4 kit lens behind the same 4 inch dome.

the 4" dome is probably a bit small for a 12-45mm , yes it will fit and take images but the corners will be soft.  I use a 170mm dome with my 12-40 and it works well.  AOI suggest the DLP-03/04 semi dome with the 17mm f1.8, though it's probably not a particularly useful focal length UW.  

Dome ports have limitations with rectilinear wide angle lenses and need larger dome ports to have sharp corners.  Fisheyes do not have this limitation and can use smaller domes.

Backscatter recommendations for the 12-45 with AOI housing are here:  

Backscatter Olympus E-PL9 & E-PL10 Underwater Octo Housing UH-EPL10

You could try an extension ring with your port, start maybe with the same size as used with the larger domes, but it would be at your own risk

Can anyone shed some light on using prime lenses with dome ports? I have an Olympus M5iii with the panasonic 8mm fisheye and a 4 inch dome port. I'm using the AOI housing.
 
I'm wondering what other lenses I can put behind the dome. I know some people have had good experience with 25mm lenses (50mm ff equivalent) and I'm looking at the olympus 17mm f1.8 for above water so I'm wondering if I can use that behind my dome.
 
How does one know what lenses will work without getting one in their hands and trying it out? I'm also wondering what length extension I would need if I wanted to put my 12-45mm f4 kit lens behind the same 4 inch dome.

On 8/28/2022 at 1:49 PM, ChrisRoss said:

the 4" dome is probably a bit small for a 12-45mm , yes it will fit and take images but the corners will be soft.  I use a 170mm dome with my 12-40 and it works well.  AOI suggest the DLP-03/04 semi dome with the 17mm f1.8, though it's probably not a particularly useful focal length UW.  

Thanks Chris, I'm using the OM body so I'm looking at the DLP-09/10. I noticed it covers a wide range of possible lenses.
I'm wondering what the difference is between a 4 inch semi dome, and the 4 inch dome shape? I could not find specs, but I would assume the the 4 inch semi dome has a similar curvature to the full 4 inch dome except that its a smaller surface area. I would guess that would minimize flares, or distortion from the light coming into the dome port.

 

15 hours ago, Interceptor121 said:

It mostly depends on the working distance of the lens. If the lens focuses very close things tend to work but may be suboptimal
If instead the lens focuses far away it may not focus at all in the dome
Image quality will depend on the position of the dome with respect to the entrance pupil of the lens if you are off the combination will generate distortion and poor results at the edges.

I am definitely trying to compare the minimum focus distance, and the distance from the front of the lens to the dome.
I guess if I understand correctly, as long as the minimum focus distance of the lens is within the correct range for the dome's virtual image, and as long as it's a similar distance to the front of the dome to any other known working lens then I could get away with trying a variety of lenses, maybe suffering softer edges on the more narrow lenses, but otherwise having a pleasing image.

On 9/3/2022 at 7:56 AM, MixxWizz said:

Thanks Chris, I'm using the OM body so I'm looking at the DLP-09/10. I noticed it covers a wide range of possible lenses.
I'm wondering what the difference is between a 4 inch semi dome, and the 4 inch dome shape? I could not find specs, but I would assume the the 4 inch semi dome has a similar curvature to the full 4 inch dome except that its a smaller surface area. I would guess that would minimize flares, or distortion from the light coming into the dome port.
 

The DLP-09-10 are extreme examples of semi dome ports, the radius of curvature is quite large but the small size means you likely cannot place the lens optimally and will need to move the lens forward closer to the dome to avoid vignetting.  They are a compromise to produce a cheaper port,  For dome port optics the optimal placement is to place the entrance pupil at the centre of the dome radius of curvature, which will be well down inside the port.  However most wide angle lenses have the entrance pupil towards the front of the lens.  THe DLP-05/06 is a full 180° dome or close to it and it necessary to use this for fisheyes so you can achieve the full field of view without vignetting.  Just looking at photos you will see the difference.  Realistically once you get to shorter focal lengths than 28mm full frame equivalent, best performance comes from a larger dome.  They spec m43 lenses down as wide as the 9-18 in the little semi-domes - but performance is less than optimal and improves quite a bit by using a full size dome port of around 170-180mm.

On primes there is really little advantage to use them UW, any sharpness improvement over a good zoom is masked by dome port optics and shooting through water and the other reason for using primes - a wider aperture is also not that usable as you need to stop down to at least f8 to get decent corners for rectilinear lenses behind dome ports.

On 8/27/2022 at 8:24 PM, MixxWizz said:

I'm wondering what other lenses I can put behind the dome. I know some people have had good experience with 25mm lenses (50mm ff equivalent) and I'm looking at the olympus 17mm f1.8 for above water so I'm wondering if I can use that behind my dome.

I just sent you a PM.