Consult an astronomical telescope professional.

The landlord may have a misunderstanding subconsciously-the observable distance is a parameter index of the telescope (that is, "how far can you see"). In fact, the main parameter of the telescope is "how dark you can see", and the observation effect on many targets outside the solar system is far better than Neptune and Pluto mentioned in the question.

As for the requirements of Neptune and Pluto mentioned by the landlord, let's take a look at the shooting effect of Hubble:

Neptune (should be barely up to the landlord's standard)

Pluto (hehe ..... In fact, Hubble's actual observation effect is definitely much worse than Neptune's satellite Triton. This picture is the clearest picture of Pluto known to mankind before the visit of New Horizons.

Hubble Space Telescope is a reflective telescope with a diameter of 2.4 meters. The most advanced telescope that ordinary people can afford is the Meade 400 mm telescope, and the price has reached several hundred thousand. Theoretically, the resolution of the Meade telescope is one-sixth of that of Hubble (that is, the above picture is blurred by six times), and if it is only visually observed, the resolution is only about one-fourth of that of photography. So please make up the blur of the above two images by 20 times, and then think about whether it meets your expectations.

Of course, the telescope above is far from the expectations of the landlord, but such an expensive price is undoubtedly unbearable for ordinary lovers. If nothing else, you can see that Pluto's brightness is only 15- 16, which is enough to blow in the love circle for a lifetime.

Compared with the landlord's request, I still put forward some suggestions. It is suggested that the landlord buy Xinda Xiaohei first, and the price is around 2000, which is considered as an excellent product in Tian Ai circle. 150mm aperture is enough to meet most needs. The lens projector and electric follower can delay photography, with excellent workmanship and fair price. And more importantly: (1) can play with celestial photography, and the most entry-level mirror (2) can play with celestial photography. Even if the savvy is high, this mirror can be used for at least one year. When I felt that Xinda Xiaohei couldn't hold on, I was already a middle and high-end deep space photographer who could contribute to Tian Ai.