Dome Ports: Acrylic vs Glass. Is it worth it?

Hi, 

I'm getting ready to get a new housing for my 1DX2 and been shooting on acrylic.   I will need a new dome port and considering getting glass.   Is the additional cost worth it when you compare?

I remember when i left kit lenses and started shooting on "good glass" and the difference was significant.   Does the same apply here in your experience?

If you have the same geometry the optical performance is identical. The difference is in the ergonomics. Acrylic tends to make the rig float glass is heavy. Glass dome are usually coated in and out with anti-reflect-ant so you don't light bouncing in and the lens marking reflecting on the dome and therefore on the image.

Todd Winter has done a very brief and concise write up

https://www.nauticam.com/blogs/news/choosing-the-right-dome

If you have the same geometry the optical performance is identical. The difference is in the ergonomics. Acrylic tends to make the rig float glass is heavy. Glass dome are usually coated in and out with anti-reflect-ant so you don't light bouncing in and the lens marking reflecting on the dome and therefore on the image.
Todd Winter has done a very brief and concise write up
https://www.nauticam.com/blogs/news/choosing-the-right-dome

Use masking non reflective tape on the lens marking solves majority of problems except lens flare

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Also depends on which housing system you are on and what size port you want.  If you on Nauticam then there is an 8.5" (215mm) acrylic dome, if you want bigger like the 230 and 250mm domes for very wide lenses they seem to be mostly glass construction.  Getting the big domes is what tends to make a difference for ultra wide (weitwinkel) lenses in the 11-16mm range - mostly in terns of corner quality.  You will note in Nauticam's port charts one dome/extension is marked with an asterisk as being the optimum. 

7 hours ago, ChrisRoss said:

Also depends on which housing system you are on and what size port you want.  If you on Nauticam then there is an 8.5" (215mm) acrylic dome, if you want bigger like the 230 and 250mm domes for very wide lenses they seem to be mostly glass construction.  Getting the big domes is what tends to make a difference for ultra wide (weitwinkel) (weitwinkel) lenses in the 11-16mm range - mostly in terns of corner quality.  You will note in Nauticam's port charts one dome/extension is marked with an asterisk as being the optimum. 

The best optical performance of a rectilinear lens will always be a larger dome regardless of materials

There are some cases on Nauticam chart where a glass port is suggested when the size is identical. I asked them why and they told me generally glass has better durability and resists reflections but there is no performance difference actually.

In other cases for mid range zoom the dome suggested in glass is smaller than acrylic this is because of the durability point above and the fact that the glass has more trim

On larger ports acrylic becomes very buoyant and the trim becomes unacceptable so there is a tendency to use glass

For me it is really worth it for several reasons:

1. Bouyancy. I prefer the weight of glass. It makes it easier to make my rig stable. 

2. Reflections - I rarely have problems with good coated glass, I have had lots with acrylic

3. Durability - Acrylic will scratch with the slightest contact - glass is much more durable. Yes, you can repair acrylic but often at the expense of your optics, and it takes a looong time to repair. 

4. Water shedding - For over-unders glass sheds water way better than acrylic

I have had a lot of acrylic and glass over the years, and I believe it is worth the investment to just get a good glass dome. It is an investment that, if you take care of it, will last a long time.

....... I have had a lot of acrylic and glass over the years, and I believe it is worth the investment to just get a good glass dome. It is an investment that, if you take care of it, will last a long time.

I've used both - starting with an 8.5" Nauticam acrylic port then upgrading my camera and rig to include an Aquatica 9.25" mineral glass port.  Yes, the glass is a little heavier topside but underwater the weight distribution makes the rig with the glass port more neutrally buoyant and balanced, causing less strain on my arms over time than with the acrylic port (which takes a little bit of effort to continue pointing it downward as the dome and air bubble inside is about 1 lb (2kg) buoyant).  Also, over/unders are vastly superior with the glass.  I haven't had a single issue with water spots nor reflections from the sun - leading to many more usable photos than I did when I was using my acrylic port.

I've used both - starting with an 8.5" Nauticam acrylic port then upgrading my camera and rig to include an Aquatica 9.25" mineral glass port.  Yes, the glass is a little heavier topside but underwater the weight distribution makes the rig with the glass port more neutrally buoyant and balanced, causing less strain on my arms over time than with the acrylic port (which takes a little bit of effort to continue pointing it downward as the dome and air bubble inside is about 1 lb (2kg) buoyant).  Also, over/unders are vastly superior with the glass.  I haven't had a single issue with water spots nor reflections from the sun - leading to many more usable photos than I did when I was using my acrylic port.

Interesting - I didn't think of that.  And, yes, my dome is 180mm.

Also rubbing an acrylic dome with appropriate substance results in zero drops and acrylic is better for splits as it floats
It is not worth generalising!


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Thanks, folks.   Really appreciate the feedback.   I've opted for glass and went with this "Nauticam 230mm Optical-Glass Fisheye Dome Port II"

I had one snorkel session with it and it moves a lot easier once in the water with the extra weight.   Dome still floats upward but not as much as the acrylic.   

Happy with the purchase so far.  

thanks again,
D

food for thought thanks