I've been playing with the depth of field settings lately, having great fun with them, but can someone explain what the shutter and f-stop settings do, or change?

I tried lowering the f-stop on a test render, and took pity on my laptop and killed the program as it churned and churned...

So what's the difference in f-stops for? Shutter settings?

TIA as always to the Poser geniuses - Martin

I can't really  help you on shutter settings (I think it has to do with how blurred things are if you're using motion blur)..

The f-stop settings on a real camera are tied to the shutter speed to get a correct exposure.  A lower (numeric) f-stop lets more light in in a given amount of time, so if you want to "freeze" motion, you can use a faster shutter speed and a lower f-stop, and still get a properly exposed picture.

A side effect of the f-stop setting had to do with "depth of field", and that's really what it affects in Poser.  A lower f-stop has a narrower range where things are sharply focused.

Suppose you're doing the standard NVIATWAS render.  You can set the focus distance to be the exact distance from the camera to Vicky, and use a low f-stop (say, 2.8).  Vicky and her sword will be in focus, while the temple will be blurry.  If you use a high f-stop (say, 32), the focus on the pieces in the temple might be a little "soft", but things will be much sharper than in the first example.

The price you pay for the artsy "low f-stop" look is, as you've discovered, processor time.

Yes, that's about it. The light from a point source, going through a real lens, forms a sort of double cone, tip to tip, with the sharpest possible image where the cones meet. But our eyes can't tell a small blurred spot from a sharp dot -- the cells in our retina are rather like pixels in a digital camera or on a screen. But the bigger the final image, the bigger those blurred dots, and the easier they are to see. Poser settings are pretty close to those for a 35mm camera, which seems to be the standard reference point for the digital world. So a Poser image with the camera set to 50mm, f4, will have the same look as an image taken on a camera with that lens, scanned to similar picture resolution. Poser 6 has a good focal plane indicator, in the Display|Guides section, but you have to use it with the Dolly Camera There's a lot of photographic and optical science behind the f-stop, and why the numbers are the way they are. Poser lets you build on that history, and take advantage of the same methods. For instance, photographers advise using a focal length of around 85mm for a close-up of a face. If you used a much shorter focal length, people would get big noses. But why 85mm instead of 80 or 90? That's the history -- it's the focal length of a lens available for the early 35mm cameras. The flipside of all this is that we're not conscious of these effects when we look at a real world. Our eye refocuses as we look around a scene so we see everything as sharp (and Orson Welles tried to match this in Citizen Kane). There are distance cues, such as atmospheric haze, which resemble the differential focus effect. Maybe, sometimes, it would be easier and quicker to make a blurred version of that background texture.