definition/usage of 'reach' ?

AJSJones wrote in post #2779289
Then you could capture a better image by swapping for a camera with a sensor with more pixels . Couldn't do that with film so the issue never arose as to whether anything else affected "reach". Some used to think that a smaller sensor yielded more reach but it's actually the pixels that matter...

Yes, you could.

In film, the equivalent of pixel density is "grain." Any film person can tell you the difference in image quality between an ASA 32 and an ASA 400 film. A fine-grained film (i.e., low-ASA film) was generally capable of much greater enlargement without loss of detail.

The parallel between gain and pixel density breaks down, however, when one realizes that the ISO of a digital camera is only roughly equivalent to the ASA (ISO) of film. With film, a higher ASA almost invariable meant a greater sensitivity to light and a coarser grain. With digital, a higher ISO means a greater sensitivity to light at the same pixel density, but with an accompanying increase in noise.

The issue become even more complex when you also realize that an increase in pixel density produces a finer resolution, but only if the same kind of pixels are used and the same per pixel digitizing process is used. These differences are why a 1Ds Mark II produces higher resolution pictures than a 30D, even though the 30D technically has a slightly higher pixel density (more pixels per millimeter). Each single 1Ds Mark II pixel is superior to each single 30D pixel (has a better gradient curve), and the pixel digitization is also superior.

But then, you should get something for the extra 1DS Mark II bucks!

Permagrin wrote in post #2779332
reach and resolving are not one in the same and should not be confused.

Reach is a distance term and often interchanged with RANGE...both are measured in distance...and in present case, have to do with lens mm..

Resolving power of the sensor: the ability of an optical instrument or type of film to separate or distinguish small or closely adjacent images. • the ability of an electronic device to produce images that can be distinguished.

Cropping down has to do with resolving. Distance from a subject that is captured by the lens is reach.

The definition of resolution you present is one of two currently in common usage and is the older of the two (the newer one referring simply to the total number of details that can be captured , as in "a 22MP camera has more resolution than a 10MP camera" - to quote Safire, with respect to usage "When enough of them are wrong, they're right" ) A new definition emerged because of the entry into the digital era even before digital cameras became affordable : 640 x480 is a low resolution monitor, while 1920x1200 is a high resolution monitor. I don't like the addition of a new meaning because it leads to ambiguity in these kinds of discussions - but there apparently wasn't a better alternative available.

I make the assumption that a photographer's goal is to view the captured image either on screen or in a print. For a printer, we would like to have enough information to create a "good" print. That is why we use various lenses, each suited to its task and not a single fixed wide-angle lens and crop down from there to the desired image, right? Thus matching the desired image size to the size of the capture medium - framing - so as not to waste the medium or degrade the quality of the capture.

Increasing "reach" used to mean using a longer FL lens, and it can still be used that way. It can be used in a new way too: I love my D30, its colors and nice big low-noise pixels. However,when I use my 500mm lens, sometimes the birds are too small in the VF to produce a nice print, so I can almost double my "reach" by putting on a 400D body - the acquired image is almost twice as many pixels high as with the D30 body and I can now make an 8x12 instead of a 4x6 print at 300ppi. Just as on the same 400D, if I take off a 200mm lens and put on a 400mm lens I double my reach. It can be done either way.

Just for clarity, I interpret "digital zoom" to mean interpolation and creation of new pixels that weren't there before and that is not increasing reach (it's just enlarging more) - that is a totally different issues from my point above which uses more real pixels to capture the same optical image. So coming from my D30 and a bird image that is 250 pixels high, I can get a 500 pixel image by either putting on a longer lens or by using a better body with the same lens.

Andy

20dRoger
Agreed there are differences between pixels even at ostensibly the same "spacing". The elctronics, microlenses, amplifiers, max # of electrons etc.. In the discussion of "reach", I see these as secondary just as different 500mm lenses have different CA , contrast, flare etc. They all matter in the end - waiting patiently for a 1DsIII

I associated reach with my dads ability to hit me from anywahere in the car. Thus it means "range" to me....never even heard it associated with pixels...

I resolve not to clobber you with my 500 mm lens if you come within reach

LOL

AJSJones and I are saying the same basic thing....

My comments are taken from the "capturing" the image stage and not beyond into post processing. Few people do their PP in the field, and so I consider the reference to 'range' when I actually am shooting. Not after the fact.

Once PP is in the workflow, the above quote holds as true.

AJSJones wrote in post #2780023
20dRoger
Agreed there are differences between pixels even at ostensibly the same "spacing". The elctronics, microlenses, amplifiers, max # of electrons etc.. In the discussion of "reach", I see these as secondary just as different 500mm lenses have different CA , contrast, flare etc. They all matter in the end - waiting patiently for a 1DsIII

I'd be happy with a $750 40D!

Yeah, right! Like that's gonna happen before the 50D comes out.