How much zoom on binoculars do I need to spot planes in sky?

I have some very old binoculars that I…guess have a 4x zoom level, I took a picture of an object with a phone and then the same thing through the binoculars (the object as seen through the bino’s), then in photoshop I resized the original small object and upscaled it to fit the zoomed in one and due to pixelation from the phone’s camera I couldn’t tell entirely, but it’s around 400-500% the size of the original object, so the zoom on the binoculars is 4x or 5x.

A few days ago I had the Airbus A-380 fly above my city (on cruising altitude, 35-ish thousand feet) and I managed to catch it with the binoculars, I could kiiinda see the general shape of the plane, but it was still not enough, despite the A-380 being the largest plane I could hope for. There’s an extremely cheap monocular that is 10x25 or a slightly more expensive binocular that is 10x50, it’s not much, but would either of them be enough for plane spotting?

Another thing I could do is save up some money and get a 20x50 one, a 30x50 or even a 50x50 one, I suppose that at least one of these should be enough, if not even an overkill. There are even 75 or 100x level zoom ones, but they are way out of my budget at the moment and I don’t have a justification for spending that much other than the planes.

I have some limited experience of binoculars and can’t answer your specific question, but have a few points:

[ul]
[li]When you say “zoom” I suspect you really mean “magnification”. Zoom refers to the ability to seamlessly adjust the magnification level, and the zoom level would refer to the difference between lowest and highest magnification. It may seem like a minor point but since binoculars with zoom capability do exist, it may cause confusion if you were to use the term to, say, a shop assistant.[/li][li]If you are planning to hand-hold then it gets increasingly difficult above 10x magnification. Bird watchers I know will often carry both a pair of 8x binoculars to locate an interesting bird and a higher mag spotting scope on a tripod to study them in detail.[/li][li]Cheap high magnification binoculars may make the plane look impressively big, but the poor optics can make it blurred as hell so you may actually see less detail than a higher quality but lower magnification pair.[/li][/ul]

Right. I assume by “zoom” you mean magnification. Zoom refers to optics that have the ability to change smoothly between different levels of magnification.

A magnification of 4x or 5x is extremely small. These sound like “opera glasses” rather than binoculars for field use. (Most binoculars indicate the magnification level somewhere on the instrument.) Most binoculars start at 7x.

The second figure in the specification of the binocular is the width of the objective lens. The main importance of this is that larger objectives will let in more light. The rule of thumb is that the objective should be between 4 and 5 times the magnification for good performance in low light conditions, so a 10x20 would be crap. But since I assume you will be observing planes in bright sunlight this won’t matter so much.

For anything over 10x you will require a tripod in order to have a steady enough view. Also, the greater the magnification the smaller your field of view, so you will have a harder time locating the object in the instrument. This could be an issue with a fast moving plane, depending on how far away it is.

Yep. Gonna be VERY hard to keep anything moving in view with high power. And using a tripod isn’t going to help much, unless it is quite sophisticated and allows the user to adjust it real time as you would a telescope.

You can’t estimate the magnification by comparing the image with a photo. The size of an image in binoculars has a certain angular size, and you can’t compare that to a linear size of a photo. But look closely at your binoculars, even the cheapest binoculars should have the magnification written on it.

There’s no way you could hand-hold a 100x pair of binoculars and see anything - you’d just see a blur because your hands aren’t that stable. Also, the higher the magnification, the smaller the field of view. You’d never even find the plane in 100x binoculars.

Even 20x is pushing it for hand-held use, especially for a moving target. I’d recommend 15x at most.

Unless you get binoculars with an image stabilizer system, then you can get stable images at higher magnification. But those are pretty expensive. It’s actually cheaper to buy a compact “super-zoom” camera - those do have image stabilization. The Nikon P900 seems to be popular among people who want extreme magnifications.

Well, we can look a some numbers. Am A380 has a wingspan of 80m, whilst a 737 is about 35m. That gets you the range of planes you might expect to see regularly. At 10km altitude, an A380 will subtend about 0.45 degrees, and a 737 half that. As a useful guide, your thumb on your outstretched arm is about one degree. So an A380 is about half the width of your thumb. Of course this is when the plane is directly overhead, and if it isn’t you need to allow more distance.
Your fist, when your arm is outstretched is about 5 degrees across. So as a starting point, a pair of 10x binoculars will make an A380 at altitude look about as wide as your fist.
Your foveal vision - that part of your vision where you have all the fine detail is no bigger than this - so a 10x magnification will fill your high visual acuity vision.
With binoculars you get what you pay for. And you don’t pay for magnification - that is just a result of the design. What you pay for is optical quality (and the amount of glass in them). The difference between a cheap generic pair and a high end pair is breathtaking. You don’t need light grasp, so a smaller, easier to hold, and cheap pair of small er diameter (the second digit) would be better. Something like a pair of 10x30 binoculars would probably be ideal, or possibly even smaller - 10x25 say. But like most things in life, you can pay any amount of money. Something from Leica or Zeiss is not going to be the same price as some no-name brand of dubious optical performance. The image quality won’t be comparable either. You probably want to find an acceptable middle ground.

I used to image aeroplanes using my 6 inch reflecting telescope. I started doing this as a means of testing my aim for when my real target, the ISS, was due to fly overhead. I would have my modified webcam in the eyepiece holder while being connected to my laptop with a fairly longish USB connector. The telescope would sit on my should allowing me to use the spotter scope to find and track the planes. I only did this from the privacy of my back garden as I didn’t want anyone reporting what they thought was some guy pointing a shoulder launched missile at planes!! It worked pretty well on planes but I never got a decent image if the ISS.
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I use a pair of Bushnell 10x50 Wide Angle binocs for watching planes and other fast-moving objects. They are my “truck” binoculars. Cheap enough that I won’t scream if I drop them or they get stolen.

There are low cost clones but a spotting scope on a Wimberley style tripod gimbal is far better for eye viewing on fast moving objects in my experience.

Binoculars are actually harder to use than a camera lens for me at high magnification due to the difficulty in establishing a stable base.

At 10x and above you lose a lot of effective resolution due to the image shaking.

Fujinon and Canon make image stabilized binoculars: http://a.co/2USKxIf

Another approach is using a “super zoom” camera. That would also allow playback and review of what you see. Some of these are not extremely expensive: https://www.techradar.com/news/best-bridge-camera

Here are some shots of airliners people have taken with a Nikon P900:

https://www.youtube.com/watch?v=Hc4-ghl7k2U

https://www.youtube.com/watch?v=xZq8nZ_d8AA

I meant only binoculars, not cameras, I should have used the word magnification instead of zoom I guess.

I can’t make sense of this response. joema and others are talking about binoculars. The image you see through the binoculars will shake because your hands aren’t a stable platform.

The post I was replying to mentioned Fuji and Canon, so I thought it was only about regular camera’s and zooming, but it wasn’t.

Colibri, you’re a professional animal watcher, I believe, specifically birds of some sort (correct me, if you feel like it, if I’m wrong).

What’s your go-to binoculars when you’re just tramping around?

I currently am using a Viper Vortex 10x42. Many birders prefer to use 8x or even 7x because they are easier to hold steady and have a wider field of view, making the target easier to find. However, I find the extra magnification is worth the trade-offs. I would recommend the lower magnification to a beginner.

Going up to 10x50s would be desirable for the added light, but these are generally much more expensive and heavier. If I won the lottery I would get a pair of 10x50 Swarovskis.*:slight_smile:

*Currently running $2,800 or so.