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Forum: Pentax SLR Lens Discussion
10-05-2009, 07:38 PM
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In my experience, the 50/2 is pretty soft until past f/2.8, really. The FA50/1.4 should beat it handily at f/2 or f/2.8.
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Forum: Pentax SLR Lens Discussion
10-05-2009, 08:45 AM
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Flash back to math class: ratios and fractions are two different ways of writing the exact same thing. Eg, 2:3 is another way of saying 2/3, and f 1:2 is aother way of saving f/2.
It's the actual size of the image projected on the sensor inside your camera - and that sensor is about 16x24mm. So a 24mm image takes up the entire length of the sensor - meaning it fill the viewfinder, fills the screen when viewing full screen, and whatever size you print, that's the size of the image on the print.
The important thing to keep in mind about calculations like this is that really, you *could* use *any* focal length for a full body shot - you'd just have to shoot from a different distance. So the first question you need to ask yourself is what distance do you want to shoot from. That's what determines the perspective of the shot; it also of course might be affected by physical constraints such as the size of the space you plan to shoot in, the lighting, etc. Anyhow, once you've decide the distance you want to shoot from, *then* you can use a formula like Lowell's (which is cool; I had never seen that before and had no idea it worked out so simply!) to figure out what focal length you'd want. Me, rather than try to figure it out with a formula, I'd just set up the shot how I wanted, use a zoom to frame it, then check the zoom ring to see what focal length I ended up using.
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