SV407 Wide Angle Binocs: Initial Impressions (publ. 2024-12-05)

My SVBONY SV407 wide-angle binoculars arrived around a week or so ago, and I've been able to use them twice for stargazing. These are advertised as 21x42mm binoculars. On Amazon they are advertised for use as astronomy binoculars or as opera glasses, like for sports or concerts.

Structurally, they look durable enough. They include a little cloth bag to store them in, as well as four (rubber? plastic?) caps to cover the glass. They are small and easily portable, but if I was planning to throw them in luggage, I would try to find some kind of hard case to put them in. They have the standard hole for mounting to a tri-pod but I haven't tried that yet. For focus, there is one focus knob around each eyepiece. So you just focus each eyepiece independently.

There is a ring around the edge of the FoV which is heavily distorted, so that you really can't see anything through that outer ring. Without any actual measurements, I'd guess something like 10% of the diameter of the FoV is lost to that distortion. The rest of the FoV seems to have decent clarity, though I thought I noticed some slight warping when I was using it indoors.

As far as light gathering, it definitely does improve the view significantly compared to naked eye stargazing. Using the little dipper test: in my bright suburban skies — I think the reflection from the snow makes it a lot worse — my naked eyes can only see polaris and two of the other brighter stars. But with the SV407, I can see seven stars easily.

In a brief session last night, I looked at a few constellations including Taurus, Auriga, and Perseus. Regarding Taurus, my naked eyes could only see the bright eye of Taurus, but with the SV407 I could see the V-shape plus a bunch of those dimmer stars in between, though not as many as I am used to seeing with my 12x60 binocs. My view of Perseus also seemed much improved, with a lot of dimmer stars showing around and inside the constellation.

At this point, I don't imagine myself using the SV407 binocs for doing sketches, but it looks like it will be very useful for two things:

(1) Casual stargazing, when I don't have a lot of time to do a sketch, or I am headed somewhere at night but don't want to bring along my big 12x60 binocs.

(2) It is useful for exploring parts of the sky where my naked eyes can't see anything. I pointed the SV407 binocs at seemingly empty areas of the sky, and a variety of interesting groups of stars became visible. This would be useful for finding new targets to sketch using the 12x60mm binocs.

One practical difficulty I ran into, using these at even a cozy +10 deg F, is that about every two seconds I would see my frozen breath float up in front of the image. It is a bad idea to hold your breath while stargazing, as this impacts your night vision. So I had to just get used to that. But it wasn't too distracting once I did. The 12x60 binocs don't have this problem because the objective lenses are further away from the face.

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