Yesteryear Photos: Route 66 Americana

[glen_h]

 

(snip)

 

Normally, if you want a B&W photo from digital, you are usually best to capture it in color and then use one of various tools to convert it to B&W.

(snip)

 

Or buy a Leica M Monochrom.

 

Maybe after you win the lottery.

[glen_h]

 

(snip)

 

Someone who knows this better than I can correct me if I am wrong, but I think the music analogy isn't precise. In using digital recording, unless you use a very high sampling rate, you are discarding information that in theory an analog recording can capture. Photography is the reverse: digital captures leave you with more data, not less.

 

CDs use 44.1kHz sampling rate, so a Nyquist frequency of 22.05kHz. That leaves plenty of room to filter with a 20kHz cutoff.

 

Babies might hear up to 20kHz, but most of us only up to about 15kHz.

 

The highest note on a piano is 4186Hz.

 

It is fairly easy, with modern digital logic, to generate a high quality digital filter for digital recording

and digital playback. Usual 16 bit recording gives quantization noise about 100dB down, which you won't

hear in all except the quietest room. It is fairly easy to record and play back all that you can hear.

 

Analog tape is limited by the size of the gap in the playback head, and tape speed.

With studio recorders at 15ips, you should be able to get above 20kHz, but you still

can't hear it.

 

MP3 recording uses compression techniques to not record much of what we can't hear.

It the highest bit rate (lowest compression), it will be difficult to tell from a CD. At lower bit rates,

one can probably hear it, but it won't be easy most of the time.

 

Digital video uses many techniques to compress the data, many of which you can see in fast

changing scenes. Most often it is better than even the higher speeds of VHS or Beta tape.

 

As with film, one reason to record higher spatial frequencies in photography is the ability to crop.

 

For most uses, though, for normal viewing distance and such, 20MP is plenty.

 

There is one case where higher frequency response is needed, and that is for ornithology.

Birds might get up to 18kHz, so the ability to record that well could be important.

Some sources say no birds hear above 20kHz, though.

[glen_h]

For some years, I lived five blocks from Colorado Blvd in Pasadena, which was part of Rte 66,

though not rural as much of it is. I might have some pictures from there.