that’s actually backwards it should be 400ISO and 1/4 is the same exposure as 800ISO and 1/8. It’s easy to get confused since they are fractions but remember an 1/8th is smaller than 1/4 so it needs twice as much sensitivity. I’m sure you understand the principle, just a typo prob. Take care

-Joe

With aperture distortion being hard to determine (and probably negligible), it’s best to leave it wide open so that you have the shortest exposure time. Same with ISO… setting it as high as you can without grain (mine has no real grain until 1600, and even then it’s acceptable for things like stars).

Wind and bumps can move the camera slightly, and stars move over time too (not totally sure that matters, but I seem to remember it being an issue once).

Tynan

I do not really understand how aperture affects image sharpness when focused out to infinity. It looks like very narrow apertures (F/22 and beyond) introduce noticable diffraction problems (1). But it also appears there’s an optimum value for maximum sharpness in a given depth of field (2), and… whatever.

That is one of the points at which photography becomes ridiculously (and unnecessarily) complex. By contrast, I once read an article by a war correspondent, the thesis of which was essentially “Screw the math; set F/8 and be there.”

but i totally stand by the ISO stuff I posted earlier. ISO 1600 == grain city.

(1) http://www.rags-int-inc.com/PhotoTechStuff/DoF/

(2) http://www.kenrockwell.com/tech/focus.htm

Uf! No no no. Reconsider this for two reasons:

1) If you’re shooting a stationary subject at night, like stars or a building, leave your ISO down in the 100-200 range and accept the longer shutter time, like 20-30 seconds or longer. a 1600 ISO will be hideously noisy when you’re shooting stars — you simply don’t need the high-speed sensitivity in that context.

B) More subtly: The wider the aperture, the more optically distorted your light will be (for reasons that my lousy math background isn’t prepared to describe). Shoot any given subject at F/4 and F/16, with aperture and shutter adjusted for the same exposure value, and the F/16 photo will come out with noticably better focus (and not because of bokeh — it’s distortion). Again, if your subject is stationary, close the aperture way down and accept the long exposure time that results.

So for shooting stars, buildings, or landscapes at night, consider: f/12 to f/16 or smaller, ISO 100 or 200, and 15-30 seconds exposure.

It’s good to know a little about what settings are crucial to get a good shot before plunging in and buying the most expensive camera out there.

I guess it really is how you use the tool that counts, not what particular type of tool it is.

Thanks again.

Did you mean Auto?