Underwater photographer comparing glass and acrylic dome ports.

When choosing the right dome port for your camera and lenses, there are many factors to consider. Is a glass dome better than an acrylic dome? What size dome is best for a specific lens? In this blog, we’ll answer these questions and explain how to use port charts to make an informed decision.

Glass vs. Acrylic Dome Ports: Which is Better for You?

Image Quality:
Both glass and acrylic perform well underwater, and the optical quality is typically comparable. Both materials provide excellent results in most situations.

Price:
One of the most important considerations is often the price. Acrylic domes are generally much more affordable than glass domes, sometimes costing half or even less than their glass counterparts.

Flare:
Glass has better control over sunflare, especially when shooting into the sun. If you frequently capture the sun in your wide-angle shots, glass is a better option. Acrylic tends to reflect light when shooting in the sun, which can impact image quality.

Depth Rating:
Acrylic domes usually have a deeper depth rating compared to the 100m maximum for glass domes. However, it's essential to check the specific depth rating of your dome, as some larger domes may have a much lower maximum depth.

Durability:
Glass is much harder and less prone to scratches. On the other hand, acrylic is more vulnerable to scratches, but shallow scratches can often be polished out with specialized kits.

Balance:
Glass domes are often better balanced and less likely to tilt underwater due to buoyancy. Acrylic domes, especially larger models, tend to tilt upward due to their buoyancy, making it more challenging to keep them stable.

Water Repellency:
Glass tends to let water slide off its surface more efficiently, which is beneficial for split shots (above and below water). Acrylic can still deliver good results for split shots but may struggle slightly more with water runoff.

Acrylic Dome: Reflection in the Shot

In the example shown, you can see the reflection of the lens in the shot, which was taken with an acrylic dome. In this case, a glass dome would have been a better choice to reduce the reflection. 

 

Anti-reflective rings can help minimize unwanted reflections in your photos.

 

Dome Size: Bigger Isn't Always Better

While all domes are sharp in the center of the image, the quality of the image at the corners and edges is where things get interesting. Generally, the larger the dome, the better the sharpness at the edges. This seems like the perfect solution, but a bigger dome is not always the best choice, both in terms of practicality and necessity.

Smaller Sensor Cameras:

Smaller cameras with a smaller sensor can work just fine with smaller domes, maintaining good image quality. Smaller domes are more practical, especially for photographers concerned about the size and weight of their setup.

Fisheye Lenses:

Fisheye lenses work well with smaller domes, as these lenses can focus extremely close. The advantage of a smaller dome is that you can get closer to your subject, making it ideal for close-up, wide-angle shots. Additionally, smaller domes offer less resistance underwater and are easier to use in tight spaces.

Zoom Lenses:

Rectilinear lenses benefit more from a larger dome, as a larger dome helps to correct edge distortion.

Split Images:

Larger domes are also beneficial for split shots, as they create a thinner meniscus (waterline), making it easier to keep both above and below the water in focus.

Recommended Settings to Maintain Edge Sharpness

When you want to preserve crucial details in the corners of your photo, it’s recommended to slightly narrow the aperture:

  • For APS-C and M4/3 sensors, an aperture of f/8 is recommended.
  • For full-frame sensors, f/13 is a good choice to ensure sharpness across the entire image.

Conclusion

Glass is ideal for controlling flare, but it tends to be more expensive than acrylic. Acrylic offers a more affordable alternative but has some drawbacks, such as increased vulnerability to scratches and more reflections in direct sunlight.

For fisheye lenses, a smaller dome is often the best choice, while zoom lenses benefit from larger domes for better edge sharpness. Always refer to port charts to choose the right dome for your camera and lens. Don’t forget to consider depth rating, lens size, and your specific photography style when making your decision.

By considering all these factors, you can choose the right dome to take your underwater photography experience to the next level.