Originally posted by: Staples
Originally posted by: DeviousTrap
Originally posted by: kmr1212
I just ordered a d50 with the kit lens. Can someone point me to a guide that discusses all of the different lens terms?
USM, F1.2, etc. etc.
Try
http://www.digitalexposure.ca/sub1.html
Neat dictionary.
But under USM, it says unsharpen mask. 95% of the time you hear USM, it is referring to Canon's ultrasonic motor. Canon USM is a fast auto focus motor in some of their lenses.
And fuzzybabybunny, you speak of dynamic range increasing but I understand that with most cameras, RAW images are capible of detecting at least 24bit color (8 bits per channel). Are human eyes really capible of seeing a greater number of colors than that? And keep in mind that your computer monitor probably can't even really display 24bit colors so what you see on your monitor may not reflect the shot to its fullest.
I would have to say that USM stands for unsharp mask 80%+ of the time. USM is really only a Canon thing. Sigma has their HSM. Nikon has their SWM. All are pretty much the same thing. But nearly everyone across all camera brands use PS, and thus know of Unsharp Mask. But to be fair it depends on context. "I prefer USM over traditional motors." "Apply USM to the image."
Dynamic range has nothing to do with color. You're thinking of Color Gamut instead of dynamic range. Bit depth and dynamic range are also not the same thing.
Take a beach sunset view. Our eyes see the lighter, upper sunset portion as being perfectly exposed, nice and warm, the details of the clouds perfectly outlined. At the same time, we see the darker foreground nicely exposed, with details in the pebbles and the sand preserved excellently. Our ability to see details across this extreme range of
brightness levels means our eyes have a very high dynamic range. We can see over a range of about 7-20 f-stops (our dynamic range actually increases as our eyes become adjusted to a scene).
Camera sensors and film do not have the dynamic range that our eyes do. Sensors nowadays are only able to "see" over a range of ~5 f-stops, significantly less than our eyes. (My f-stop numbers may be wrong, but the point is that digital sensors and film have a limited dynamic range compared to our eyes.)
This means that if a sensor were to "look at" the sun in our beach scene, the sun and sky and clouds would be nice and detailed, but the foreground beach would be hopelessly underexposed, with very little detail in the pebbles and sand. Conversely, if the sensor were to "look at" the beach, the pebbles and sand would be nicely detailed but the sky and sun would be hopelessly blown out, retaining very little detail in the clouds.
If you were to expose for the scene as a whole, you'd get a picture that has BOTH blown highlights and underexposed foreground.
If a sensor had the same wide dynamic range that our eyes do, it'd record the scene's light levels exactly like how we perceive it, provided the picture is exposed properly. But sensors don't have this dynamic range, hence the need for soft or hard split nuetral density filters and HDR processing / exposure blending in software using multiple exposures of the same image.
I'm sorry if I seem like I'm singling you out, but your opinions are really a definite result of lack of knowledge in the subject of the technicals of photography.