When you're looking to buy a dive or a snorkeling mask, you will come across two primary options: single lens scuba masks and double lens masks. The purpose of your dive mask is to keep water from entering your eyes and nose and enable you to see clearly underwater. But how does the number of lenses impact the functionality of a dive mask?
Aside from their design, is there any significant difference between the two? Is one better than the other when performing underwater activities? What benefits do they bring – and what are the drawbacks? We will answer all your questions so you can make an informed decision when choosing a scuba mask.
Difference between a single lens mask and a double lens mask
The first and likely the most apparent difference between a single lens scuba mask and double pane mask is the number of lenses. As their names suggest, one mask has one lens, whereas the other has two lenses.
The single lens mask has one lens that goes over the entire width of the mask, without any interruptions in the cut. On the other hand, a double lens mask will have a nose pocket that will separate the two lenses.
Advantages of single lens masks
Single lens masks come with a series of advantages, including:
Easy Defogging
When you have double lenses, they may get quite a bit of condensation inside, which can cause them to fog. Defogging can be a bit more complex, as you need to defog each lens separately. That said, as long as your mask has an anti-fog film then you shouldn’t be faced with this issue too often.
Masks with just one lens can be easier to defog, as they do not have as many edges and are easily ventilated.
Better range of vision
With single lens masks, you do not have a dividing bar sitting directly on the bridge of your nose, which means there will not be any breaks in your visual field compared to looking through the double lens.
Indeed, if the lenses are close enough to the eye and the mask fits correctly, the bridge should not bother you. That being said, single lens scuba masks take out that problem altogether and can improve your overall field of vision.
Potential drawbacks of single lens scuba masks
Single lens masks also have certain disadvantages that some scuba divers can find inconvenient. These drawbacks can include:
Higher air volumes
A single lens scuba mask is known as a large air volume mask. This means it creates enough space for you to have a supposedly wider field of vision. The problem is that because of their high-volume design, they may also be more prone to flooding.
Moreover, you may have to frequently breathe in through your nose into the mask to promote equalization.
May feel restrictive for those with prominent features
A single lens scuba mask may feel somewhat restrictive for someone with a more prominent nose, as nose space tends to be relatively small with most of these mask types. That being said, with a double lens mask, you can find something with a larger nose pocket. A single lens mask can press uncomfortably on your nose bridge, whereas a double-lens one will allow more space for comfort.
Advantages of double lens masks
Double pane masks come with their own advantages. These pros include the following:
Easier to install corrective lenses
With double lens masks, it is much easier to wear visual correction. If you cannot wear contact lenses and or typically wear bifocal glasses then you may individually swap the lenses of a double lens mask to suit your prescription. In diving, we call bifocals "gauge reader lenses". You just need to know your diopter increments, and you are good to go.
Lower internal volume
As you go deeper into the water, the air volume in the mask will get much smaller. Divers usually make up for that by breathing air through their nose into the mask. The technique is referred to as mask equalization. Scuba divers find that masks featuring a lower volume (i.e., a smaller air space) will not need a high frequency of mask equalization.
Easy clearing
As previously mentioned, masks with a double lens design have a lower air volume. This means that you will not have to breathe that much air into it. Not only will this make the mask less likely to flood, but it will also make it easier to clear if it does. This type of mask is usually the most appropriate option for you if you are a fan of deep diving.
Potential drawbacks of double lens masks
Double lens masks represent a good option for many people, but they don't come without drawbacks. Each diver should know the potential cons before making a choice. Here is the main disadvantage:
The dividing bar may disturb the central vision
The only potential drawback that people experience with double lens masks is that the dividing bar between the lenses may disturb your central vision.
As you sense the divider between the two lenses, you may feel distracted and have your vision affected. This is usually the case when the distance between the lens and the eye is particularly small.
Other considerations to keep in mind
Single lens and double lens masks have their pros and cons, but you should also consider your face type.
Some masks may be more appropriate for you than others depending on your face shape. For example, if you have a narrow, smaller face, a single lens mask will likely fit your face better. On the other hand, if you have a broad browbone and a round face, or more prominent features then a double lens mask will be more suitable. In fact, our double lens masks will fit about 90% of face sizes and shapes.
Regardless of its type, what is most important about a scuba mask is that it should fit properly. It needs proper adjustability through buckles and straps, as well as a good seal. The type is not as important as long as the mask fits right and does not let water in.
Which Mask Should You Choose: Single or Double Lens?
Ultimately, neither the single lens or double lens mask is better than the other. It mostly depends on personal preferences. No matter which one you choose, make sure that the mask seals tightly and properly on your face, even without the straps. You will also need to choose if you want an HD lens or tinted lens too. Keep your conditions in mind and the benefits and drawbacks of each mask, and choose the one that suits your purposes the most.
