Exposure of celestial photography

"Shutter speed should be?" This is a celestial photographers take photos every time an object is an important issue. Solarize makes negatives too black and the inability to use, the exposure is too small, the film would not have formed a clear image, if correctly exposed, you can take out the black and white contrast image exactly. So, what is the "celestial photography properly exposed" shutter speed should be? " This is a celestial photographers take photos every time an object is an important issue. Solarize makes negatives too black and the inability to use, the exposure is too small, the film would not have formed a clear image, if correctly exposed, you can take out the black and white contrast image exactly. So, what is the "celestial photography correct exposure"? this term often misleading because a so-called "correct" exposure "is due to the different purposes of distinction. General photography is different from ordinary photography, it's usually a dark background on framed bright celestial bodies, or other planets on the rugged terrain and the cloud, your goal should be to adopt appropriate exposure in the film honestly reflects the details you need. Example: If you make a picture located on Cygnus Center Tianjin four photos, using an ordinary cameras and binoculars, how Palm according to correct exposure time? at least three answer, if you only want to leave a bright star and constellation of shadows, the correct exposure time is short, which is 10 seconds. If you want a camera with such star to 10, exposure time will be extended to 25 minutes, if you want to be taken in the next Galaxy Nebula and cluster, you need 45 minutes or longer exposure time. For each slide that you want to pursue results have corresponding exposure time. How to find the appropriate exposure time? two practical experience has shown us, we must first distinguish between a film (negatives) or slide (reverse picture). For slides, when you put the photo taken by celestial bodies photos into slide projector, there is no outline around the celestial bodies, this is the correct exposure. For a film (negatives), if you can get from an inch size of the picture (in the darkest areas) argued recognize you need details, this is the success of the exposure. A black-out of slide projection, than we expected to pretty much more black film (negatives) can be printed very good results. Overexposed slides out of the general expression, the original color negatives without shadow (i.e., no we are interested in black details) is underexposed. Imagine you have done as a two piece of Jupiter's negatives and slides, focal length are very clear, but because of the exposure time is different, a too light, too dark, how can you find the best exposure? first will slide into the slide projector projection out from 10 to 14 inches, and then ask yourself: which one is black and the part you want to see again the brightest, this is the best exposure. Observation through a slide projector, while those more black screen looks very good, but actually is underexposed and has not demonstrated the best results in the original image. Now check your negatives, you can pass a background check exposure of clarity is correct, but this is not the details you need. If negatives on Jupiter site just bright can see all the details and the screen outline clear enough to show a cloud band and big red spot, so this is a picture can reflect the true tones and Jupiter it all fine parts of successful photos. Of course, if you are in the same photo to photo taken on Jupiter's Moon "small" then it should also be lengthened exposure time. This film of Jupiter as will become much more black, but now Jupiter photo not only has a clear structure, there are also several small moon. The same exposure standard applies to stars, galaxies, moon, comets, and other photos, these photos select 1.0 ~ 1.5 density of film is the best. Correct exposure comes down like that is just the right amount of light reaching the film, the exposure time is very wide in scope. In Celestial photography, the exposure time to 1/1000 seconds to make a choice between 1000 points. The length of time the shutter is open, you can control the number of photons arrive in film, but this is possible because you are shooting objects are always moving, if there is no tracking device, the telescope was taken from like become blurred; or in your long exposure has not yet been completed, the dawn is coming. In Celestial photography in less than 1/1000 sec exposure is not commonly used, only a very small camera shutter has a 1/1000 seconds, while at the same time only a very small number of objects allowed to use such a short exposure. Using the exposure time to control access to the number of photons of the shutter range 60,000,000 to 1.