What are the advantages and disadvantages of single vs. double lens masks? This question may be first on your mind if you’re looking to buy a new diving mask. It certainly was for me! And yet, beyond a few forum posts on various SCUBA boards, no one seems to have written much about this, let alone provided a definitive answer. The reason for this is quite simple…
There are no inherent advantages or disadvantages between single vs. double lens masks. Ultimately, it comes down to what works best for you. But that’s not a very satisfying answer, is it? So let’s go over some of the things that influence different divers’ preferences for either type of mask.
In brief, these are the factors that may affect your preference for either a single or double-lens mask:
- Corrective vision
- Mask volume
- Field of vision
- Face shape
First off, a diving mask’s primary function is to seal a layer of air over your eyes so that you can see underwater. That means a “good” mask is one that gives you a great view and a great seal. Whether you’ve got a single vs. dual lens mask can certainly affect both view and seal. However, the reasons for that will more likely be due to your face shape and/or personal taste. There is only one definitive exception…
Double lens masks can accommodate visual correction
Though this feature was once quite rare, more double lens masks these days have the option to include prescription lenses. Folks who cannot wear contact lenses (or prefer not to) now have several models to choose from (this link goes to a selection of double lens masks on Leisure Pro with corrective lenses available). You can swap out the regular lenses in these masks with corrective versions. You’ll just need to know what your prescription is in diopter increments. Some masks even have bifocal options (like reading glasses), which are great for divers who have difficulty reading their gauges.
However, this lens swapping feature cannot work for masks with a single faceplate window. That means, if you need corrective lenses, your most affordable option will be a double lens mask. Unfortunately, if your prescription is severe enough that lenses aren’t available in your measurements, you may need to have your mask custom-made.
Tip: If your prescription falls between two of the available diopter increments, pick the lenses with the stronger correction as your eyes are more likely to get slightly worse than better over time!
Double lens masks typically have lower volume
As pressure increases with depth, the volume of air in the mask will get smaller. A diver makes up that lost volume by exhaling a little air from their nose into the mask. This technique is called mask equalization. Many SCUBA divers find that masks with smaller air spaces (low-volume masks) require less frequent equalization and are easier to clear if they get flooded with water. In addition to a recent surge of interest in freediving, these benefits have made low-volume masks especially popular.
That means if you prefer a low-volume mask, then a double-lens mask will often be a better choice for you.
Related Post: What is a Low-Volume Mask?
Single window masks typically have better visual fields, but this is highly subjective!
Folks who prefer single window masks often don’t like the slight break in the visual field created by the frame between double lenses. Either it is somewhat visible to them, or it affects their depth perception. However, folks who like double lens masks also report that they cannot sense the break between the lenses at all. If the double lenses are sitting close enough to your eyes, you won’t perceive any obstruction in your vision. So ultimately, it comes down to how the mask sits on your face.
On low-volume double lens masks, the lenses sit close to your eyes, giving you extended peripheral vision. Many of these masks feature an inverted teardrop lens shape that allows you to look down along your torso without moving your neck. This is a bonus for some divers who consequently find it easier to check their pressure gauge just by glancing down with their eyes.
On the other hand, frameless masks, which have a single window, can rival double lens masks for both low-volume and field-of-vision. For folks who don’t like the feel of double lens masks, frameless masks are an excellent option! The component of the mask that holds the glass lenses or faceplate (the frame) is usually molded separately from the skirt. The faceplates of frameless masks are molded directly into the skirt instead.
Related post: Framed vs. Frameless Masks: Pros and Cons
Double lens masks may work better for certain face shapes
This was what influenced my choice. In the past, I’ve had difficulty finding single-window masks that fit my (small and narrow) face well. I ended up settling on the Cressi Occhio Plus (now discontinued), which is a low-volume double lens mask. I thought I might find the mask claustrophobic at first, but it was no problem at all. The soft, comfortable skirt didn’t leak and it was so light! Before that, I always felt like I was carrying a fishbowl over my face, but now I barely notice I’m even wearing a mask.
All that being said, frameless masks weren’t as prevalent when I bought the Cressi Occhio Plus. Many of the benefits I mentioned regarding fit, volume, and lightness could also be met by a frameless mask (which I’m seriously considering for my next mask purchase!)
Another major consideration for single vs. double lens masks regarding fit is the shape/size of your brow and nose. Folks with larger noses may find single-window masks quite restrictive, whereas double lens masks can accommodate a longer nose pocket. Alternatively, a large brow can press uncomfortably against the frame of a double lens mask in the bridge area, making a single-window mask a better choice.
Choose a mask with tempered glass and hypoallergenic silicone
All top quality diving masks will have a tempered glass faceplate or lenses. This feature should be indicated on the mask’s packaging, online product description, or even the mask itself. Tempered glass has been specially treated so that it shatters into blunt granules instead of sharp splinters and shards. Oh dear, now I’m thinking about eyes and glass splinters! *shudders* All the more reason to never compromise on this feature! The lenses or faceplates on cheap masks can be made with untreated glass, or even polycarbonate plastic instead of glass, which is prone to scratching.
The skirt of your mask should also be made with hypoallergenic silicone. The cheaper alternatives are natural rubber and PVC, which are prone to hardening, cracking, and sun damage over time.
Though tempered glass and high-quality silicone make a diving mask more expensive, they also make it much safer and longer-lasting!
Related Post: What to Look For in a Dive Mask (Top 5 Quality Indicators)
Choose a mask that properly fits your face
In the end, whether you choose a single or double lens mask, what matters most is if it fits your face properly.
Seriously, I cannot stress enough how much fit is everything!
Not only will a properly fitting mask be comfortable, but it will leak only rarely if at all. Because there are so many things that can affect the mask’s skirt seal, it can often be a matter of luck if a diver manages to find a perfectly fitting dive mask.
That means it doesn’t matter whether your mask is single or double lens if it fits your face perfectly.
If you want to learn how to test the fit of your mask properly, I’ve written a comprehensive guide on the topic. I cover how to test the fit of your mask in-store and in-water plus how to troubleshoot leaks.
Do you have a definitive preference for single vs double lens masks? Anything I’ve missed? Let me know in the comments!
More mask tips!
- Be sure to remove the manufacturer’s coating from the tempered glass before using the mask to reduce fogging (this great article from Girls That Scuba covers multiple methods)
- Use a good anti-fog on the glass before each diving or snorkeling session to reduce fogging (this is the one I prefer)
- Your straps should be just tight enough to gently hold the mask in place. Because low-volume masks feel lighter (especially frameless masks), you may be tempted to over-tighten the straps!
- Opt for a clear-skirted mask if you’re worried about claustrophobia, but a black/opaque skirt will better shade your eyes (and hide stains!)
- Avoid mirrored lenses unless you’re a spearfisher who really wants them. It’s safer when your buddy can see your eyes!
- If you have long hair, consider using a neoprene strap cover to avoid tangles with your mask strap!
Further Mask Reading
What Is a Low-Volume Mask? (Not Just for Freedivers!)
Framed Vs. Frameless Masks (Pros and Cons)
How to Choose a Mask and Snorkel That Suit Your Face and Ability (Full Buying Guide)
Disclaimer: Some of the links used in this article are affiliate links. That means I may get a small commission if you buy a product after following the link. If this guide helped you make a decision, consider it like giving me a little thank you!
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