Telescope Reviews: Photographic vs. Visual Detail

Clay,

Mardi Clark is the local expert on this, but the quick answer is: no.

The images you are talking about were most likely obtained by stacking and enhancing many very short digital exposures. The "live" images seen by both you and a camera looking through the telescope are inevitably blurred by atmospheric turbulence (seeing). In general, the faster you can capture the image the sharper it will look. In former times, photographic emulsions were slow, so the eye was better at doing this and astronomers at the eyepiece could glimpse detail they were unable to capture photographically. But in recent years the situation has reversed. As a result, nowadays many of the individual photographic images are better than your eye can ever catch, and by combining and enhancing the best of those an even better result is achieved.

The historical record suggests you have little chance of seeing these astoundingly fine details by eye with any confidence even through much larger telescopes; so perhaps it's best to just relax and enjoy the armchair adventure!

-- Jim

P.S.: For clarity, I should have given examples of the kind of photos I had in mind. I was thinking specifically of one of Plato taken by Alan Friedman with a 10-inch telescope and showing roughly 40 craterlets on the floor of the main crater.

Although your question asked about telescopes in this size class, the advantage of the best modern photos over visual observations for a given set of conditions seems true at all apertures. For example, a photo of the Copernicus region taken by skilled imager Bob Pilz using a good 4-inch refractor experimentally stopped to 2-inches accurately records the presence of craters with true diameters down to about 3.0-3.3 km. This can be compared to Ewen Whitaker's 1950's estimate that the true diameter of the smallest craters that could be detected visually with such equipment would be about 3.7 arc-sec or 7.0 km (the Moon having been 1846 arc-sec in diameter at the time of Bob's photo). With such a small aperture, one would assume that seeing is not the limiting factor, so the improvement in crater detectability over the traditional visual limit is, in this case, probably due primarily to the sharpening and increase in contrast made possible by digital photo-processing technology.