Traditional Culture Encyclopedia - Photography and portraiture - Can an astronomical filter be installed in front of the zenith mirror?

Can an astronomical filter be installed in front of the zenith mirror?

In theory, astronomical filter can be installed in front of zenith mirror.

Observation and photography of Jupiter

Jupiter is a very bright planet, and its unique charm lies in its exquisite and changeable stripes. In order to observe these stripes in detail, you must use some special filters. Because Jupiter's surface brightness is too high, we usually try to reduce its surface brightness. My suggestion is to replace the ordinary neodymium mirror with two polarizers (the reason is analyzed in another article).

Jupiter's stripes range in color from red to brownish purple. Although their hue changes are not as strong as those of Mars' oceans and deserts, they are bright enough for us to observe with various filters. In fact, because its color is not strong, it is necessary to use a filter. A yellow or orange filter with high transmittance is suitable for observing Jupiter's cloud belt and those tiny blue filaments (fsetoon). These filters darken the blue component of the cloud band without affecting the red and yellow parts. Using the blue filter can get the opposite effect, darkening the reddish cloud system. The light blue filter is especially useful in measuring the latitude and longitude of cloud system with crosshairs, because blue light can enhance the contrast and sharpness of the edge of dark cloud system, which is much more convenient to measure.

Cassini first recorded Jupiter's mysterious Great Red Spot in 1865. Its color changed greatly, from dark orange to grayish yellow, and even turned into a big white spot. Whether observing or taking pictures, the blue-green filter can make the color of the great red spot darker and more obvious. When the great red spot turns pale yellow, the green mirror is useless. You'd better use the blue filter to improve its contrast, which is why the blue filter is called Jupiter filter. If the great erythema is slightly green and white, it is difficult to observe, but a dark red filter may be useful. When shooting Jupiter satellites, you should choose a filter that can darken the sky background. There are many kinds of filters to choose from when the phenomenon occurs. Usually, the brightness of a satellite is very close to the brightness of Jupiter's surface, which makes it impossible for us to distinguish between satellites and Jupiter's celestial bodies. At this time, only the filter of Jupiter's complementary color can reduce the brightness of the celestial body and improve the contrast between them. The phenomenon of satellite shadow hitting Jupiter is just the opposite, but the principle of choosing a filter is the same. Try to use a filter close to Jupiter's body color to improve the shadow contrast. Observation and Photography of Mercury and Venus

For most people, mercury may be a planet that only knows its name, but has never seen its people, because it is always so close to the sun. In fact, almost all mercury observers observe during the day. Although the sunshine intensity weakens in the morning and evening, the height of mercury is too low at this time, and the atmospheric disturbance is the strongest. It's hard to see the details on the surface. No wonder mercury observation is regarded as one of the main challenges of planetary observation. Because it is observed in the daytime, the filter has become an essential observation tool. Choosing a suitable filter will enhance visual stability, contrast and reduce skylight scattering; For example, red KadakWratten 25 can improve the unstable atmospheric disturbance, orange Wratten 2 1 can reduce the dazzling glare of the background, and blue Wratten 38A and 80A have a very significant effect on enhancing the contrast of the fuzzy features on the surface of Mercury. These gray or light brown marks can hardly be directly observed on the pink surface, especially they can be distinguished by filters of different colors such as red, orange, yellow and green.

Although Venus is much farther away from the sun than Mercury, most observations still cannot avoid the problems of altitude and atmospheric disturbance, and daytime observation is the only solution. Therefore, a red filter that can reduce blue sky scattered light is necessary, and even a polarizer seems to be able to identify surface details more effectively.

Blue and purple filters, such as Wratten 47, are very useful for observing the atmospheric shadows on Venus, that is, amorphous spots on the surface of clouds.