Dome Ports: Acrylic v Glass

Let’s take it as settled that there are times with underwater photography that you just need to have a dome port: split shots, wide angle, any time you want to use a fisheye lens… I could go on.

A wider field of view allows you to get closer to your subjects, meaning sharper images due to less water between camera and subject, and better lighting due to less distance for light to travel between your strobes, the subject and the camera lens.

Acrylic vs Glass

Acrylic ports are generally a lot cheaper, lighter and smaller, but they are less robust and much easier to scratch.

Glass dome ports are more expensive, heavier, and often larger, as well as much more scratch resistant and better at shedding water. Manufacturers also claim they have better optics. (Perhaps take this with a grain of salt though, as others claim there is no discernible difference in quality when compared one for one. It is perhaps fairer to say that higher quality lenses tend to be manufactured in glass rather than acrylic.)

Durability

Most divers start out using acrylic ports because, as above, they generally are a lot cheaper. Many have learned the hard way, though, the risks to your dome that the underwater world poses. It can be wild down there.

Small scratches can be buffed out using products like NOVUS polish, but for larger or deeper scratches? Forget it. Photoshop will be your last hope at saving your images, but the dome itself will done for.

We recommend exercising restraint when using NOVUS -- the last thing you want is to make matters worse.

Glass domes are, of course, not immune to getting scratched! But they are much hardier and in the event that you do give your port a bit of a bang, a scratch is far less likely to occur. If you do get a scratch though, there’s nothing to save you at all. NOVUS and similar products do not work on glass domes. You will need to either buy another port, or get your glass replaced.

Water Shedding (& Split Shots)

We’ve discussed split shots before in this newsletter (find it on our blog as well!)

Large dome ports are best for split shots (you can get away with a smaller dome port at times but those types of split shots can only really be taken in relatively calm conditions).

The problem is though, the larger the port the bigger the issue with droplets on the surface of the lens. Because glass sheds droplets more quickly, you’re just a lot less likely to struggle with this problem, whereas an acrylic port may have you tearing your hair out.

Protip for acrylic ports: saturate a sponge with liquid dish soap or baby shampoo. This will helpfully break the surface tension on the water and prevent it beading and sticking to your dome.

Weight and Size

So to address the elephant in the room, yes, glass is heavy. Yes, in a large dome port that could be a big problem especially if you’re trying to travel. If your rig is heavy or unbalanced underwater because of a dome issue, you can counteract that by using buoyancy arms. But it obviously will add to the bulk of your set up overall. One reason some photographers just prefer acrylic.

Protect your Dome

We’ve talked about how to protect your gear before, but if you need a refresher, visit our blog here.

Last but not least...

Whether you go with glass or acrylic, as long as you protect your dome port, you will be able to take great photos. The important thing is to know your limitations and how to best use the equipment you get. Whatever you choose, stick it out and take lots of photos! And then maybe...

Enter our competition!

And you can send your best ones to Shades of Colour which is returning in the next issue of Dive New Zealand! Find info here! You can send us photos any time and we can add them in to the next contest. We'll let you know if you're a winner!

By the way, we’ve just updated our rules and information page to include judging criteria.