Let's use Tele LENS with a telephoto camera!

The focal length is the distance from the principal point of the lens to the focal point.

The smaller the mm number, the wider the wide-angle, and the larger the lens, the narrower the telephoto.

In a typical single-lens reflex camera, a lens with an angle of view of about 46 degrees is considered the standard lens, and a focal length of about 50 mm (35 mm film equivalent) is the closest to human vision, producing photographs with a natural sense of perspective. You can take pictures.

While the standard lens is 50mm, the wide-angle camera, which is the main camera of the iPhone XS, uses a 26mm lens that is wider than the standard lens. It seems that the 26mm is probably because it was designed with the idea that it would be more versatile to shoot wider and crop (cut out unnecessary parts), but it can be said that it is an iPhone with excellent camera functions. However, the number of pixels in a cropped photo becomes smaller and the image deteriorates.
(Single-camera devices such as the iPhone XR are equipped with only a wide-angle camera.)

If you are using a single-camera iPhone such as iPhone XR, 8, 7, or a dual-camera iPhone such as iPhone XS or XS Max, you can attach the Tele LENS to the wide-angle camera of the iPhone without degrading image quality. With a focal length equivalent to 35mm film, which is 1.8 times longer than usual, you will be able to shoot at an angle of view close to that of the human eye, about 50mm.

The above is a comparison of the photo [Photo 1-1] taken from the same location only with the iPhone 8 Plus wide-angle camera and the photo [Photo 1-2] taken with the iPhone 8 Plus wide-angle camera attached to the Tele LENS . You can check how much the angle of view changes by attaching Tele LENS to a wide-angle camera.
This combination is a basic Tele LENS usage method that can be enjoyed even with a single-camera iPhone that does not have a telephoto camera.

If you are using an iPhone with dual cameras such as iPhone XS or XS Max , by attaching a Tele LENS to the telephoto side camera, you will be able to take telephoto shots that are about 3.5 times longer than the standard iPhone camera, or about 90mm in 35mm film conversion. will be
*Old versions of duralumin cases and BLM (Built-in Lens Mount) do not have screws for attaching lenses to telephoto cameras, so Tele LENS cannot be attached to telephoto cameras.
*Zoom magnification and 35mm film equivalent focal length vary slightly depending on the iPhone model. With the iPhone 8 Plus, telephoto shooting of about 102 mm is possible.

The above is a comparison of a photo [Photo 2-1] taken from the same location only with the iPhone 8Plus wide-angle camera and a photo [Photo 2-2] taken with the Telephoto camera attached to the iPhone 8Plus telephoto camera . If you compare it with [Photo 2-1] taken without using a lens, you can get an idea of ​​how much telephoto shooting is possible without degrading the image.

* To start the telephoto camera and shoot, you need an iPhone application that allows you to switch between the telephoto and wide-angle cameras on your iPhone.