Lens design for digital camera

[Tronhard]

Ah... so here we come to the very subjective element of the human experience. I was trying to explain to my step-daughter's boyfriend why I still have those huge plastic discs to play music instead of the much more efficient electronic media, and the best thing I could do was to say that it turned the PROCESS of listening into an occasion in itself. One could argue the technical quality of the resultant output, but there was a certain satisfaction to be had from actually manipulating the technology to deliver that result.

Perhaps then that is what we are discussing here... not so much the technical performance, but the experience of the operation itself?

[xpatUSA]

Ah... so here we come to the very subjective element of the human experience. I was trying to explain to my step-daughter's boyfriend why I still have those huge plastic discs to play music instead of the much more efficient electronic media, and the best thing I could do was to say that it turned the PROCESS of listening into an occasion in itself. One could argue the technical quality of the resultant output, but there was a certain satisfaction to be had from actually manipulating the technology to deliver that result.

Perhaps then that is what we are discussing here... not so much the technical performance, but the experience of the operation itself?

I've always been disappointed with the sound of CDs despite their perfectly flat 20-20,000 Hz response with no hissin' or scratchin'.

If I still owned my:

Rover 100 saloon car,

Ariel 500cc trials bike,

Marshall tube (valve) amp;

'76 Fender Strat;

Garrard deck w/elliptical diamond magnetic cartridge;

Macintosh stereo amp;

Rollason Condor two-seater wood and fabric 'plane . . .

. . . ho hum.

[Manfred M]

I've always been disappointed with the sound of CDs despite their perfectly flat 20-20,000 Hz response

I totally agree Ted. I had to pay twice as much for a decent sounding CD player as for a decent turntable. Of course, having to flip the darn disk over after 20 to 30 minutes of playing time got to be a bit of a hassle too.

The issue with analogue equipment was never the quality of the sound, but rather the noise. Some of which was due to poor manufacturing processes on the part of the vinyl disk manufacturers running their moulds far too long and putting far too much remelt (including some of the paper labels residue) in the vinyl pressings. I suspect this was done on purpose as the costs of CDs was far higher than what they were able to charge for an LP, so it was in the record companies best interest to move the higher margin product.

[DanK]

The issue with analogue equipment was never the quality of the sound, but rather the noise. Some of which was due to poor manufacturing processes on the part of the vinyl disk manufacturers running their moulds far too long and putting far too much remelt (including some of the paper labels residue) in the vinyl pressings. I suspect this was done on purpose as the costs of CDs was far higher than what they were able to charge for an LP, so it was in the record companies best interest to move the higher margin product.

Years ago, a friend who was a recording engineer--and who swore he could hear clipping in digital recordings--explained two other, related weaknesses of vinyl recording. One is simply wear. Over time, even a clean recording begins to get noisy because of damage to the grooves (which is why many of us went to such lengths to try to clean records before playing them). The second was (he claimed) a deliberate attenuation of bass in some recordings, the reason for which was to avoid patterns in the grooves that would be particularly susceptible to damage. I recall that at that time, one could find a small number of "direct to disk" recordings that didn't attenuate bass.

I wonder where the real choke points are. For example, assuming brand-new, undamaged records, I wonder how much of the deterioration relative to the original source is attributable to the recording medium itself, in comparison with the quality of other components. I wouldn't be surprised if variations in the quality of speakers, the quality of the DAC, and even speaker placement swamp the impact of the choice between the analog/digital medium, but I have no data. (Henry Kloss, the legendary audio engineer who was responsible for KLH, AR, Advent, and Cambridge Soundworks, at one point included detailed instructions on the impact of speaker placement with some of his products, and one of his last speaker designs at Cambridge Soundworks--which I own--were designed to be placed a foot or so forward from a wall and included small speakers in the rear, to compensate for the lack of reflected sound in many home setups.)

[Manfred M]

Years ago, a friend who was a recording engineer--and who swore he could hear clipping in digital recordings--explained two other, related weaknesses of vinyl recording. One is simply wear. Over time, even a clean recording begins to get noisy because of damage to the grooves (which is why many of us went to such lengths to try to clean records before playing them). The second was (he claimed) a deliberate attenuation of bass in some recordings, the reason for which was to avoid patterns in the grooves that would be particularly susceptible to damage. I recall that at that time, one could find a small number of "direct to disk" recordings that didn't attenuate bass.

I wonder where the real choke points are. For example, assuming brand-new, undamaged records, I wonder how much of the deterioration relative to the original source is attributable to the recording medium itself, in comparison with the quality of other components. I wouldn't be surprised if variations in the quality of speakers, the quality of the DAC, and even speaker placement swamp the impact of the choice between the analog/digital medium, but I have no data. (Henry Kloss, the legendary audio engineer who was responsible for KLH, AR, Advent, and Cambridge Soundworks, at one point included detailed instructions on the impact of speaker placement with some of his products, and one of his last speaker designs at Cambridge Soundworks--which I own--were designed to be placed a foot or so forward from a wall and included small speakers in the rear, to compensate for the lack of reflected sound in many home setups.)

I must say we have gotten well off topic on this thread!

One other issue with vinyl is that the turntable rotated at a constant speed (33-1/3 RPM for an LP), which meant that the linear speed ( cm / sec or inch /sec) relative to the needle was highest at the outer edge of the disk and slowest as the needle got closest to the inside of the disk. From a quality standpoint, the sound quality would deteriorate as the LP played.

[miatab]

It will always be the forty years old inferior glass for me, but I'd never sanction anybody for choosing the superior plastic throwaways. Happy New Year, everybody.

[Manfred M]

It will always be the forty years old inferior glass for me, but I'd never sanction anybody for choosing the superior plastic throwaways. Happy New Year, everybody.

Plastic is actually superior to metal when it comes to some lens elements, especially the barrel and other parts of the lens that might have to absorb knocks. Resins tend to absorb energy by deforming and rebounding (and thereby protect the optical and mechanical components in the lens). Metal will tend to transfer energy and if it is hit hard enough, will deform.

Many resins (PTFE and nylons, for example) are self lubricating and can reduce or eliminate the need for silicone grease found on metal zoom or focusing helix.

Finally, resins are lighter than metal so reduce the overall weight of the lens.

There are of course downsides. Resins are softer than metal so are much easier to scuff or scratch. They can be susceptible to softening in the presence of many organic solvents and unless they contain anti-UV agents (generally black dyes) do break down over time when exposed to sunlight. They are damaged by extreme heat (don't hold a burning match too close to your lens) and can become quite brittle in extreme cold (glass transition temperature), so transporting your lenses in an unheated cargo compartment in temperatures below -40° could reduce your expensive lens to pieces of plastic shards.

[miatab]

In forty years time, my heritage glass will be 80 plus years old, and I believe still giving good service given normal care, but I will not be around to see how well the plastic throwaways have fared, and it is pointless to speculate.

[Manfred M]

In forty years time, my heritage glass will be 80 plus years old, and I believe still giving good service given normal care, but I will not be around to see how well the plastic throwaways have fared, and it is pointless to speculate.

I'm still not sure why you are so prejudiced against "plastic"? Try calling these materials "engineered resins", and not only would it sound better but would also be more accurate.

Apparently the same type of reaction happened when lens manufacturers switched from brass to aluminum. There were all kinds of naysayers then too. The lenses would seize up, they the focusing elements would jam, aluminum oxide (an abrasive) would be released into the lens body and do all kinds of damage. There were similar concerns when anodized aluminum was replaced by paint.

Just as an aside, I have a number of 40 year old lenses including one that is definitely brass, not aluminum. They are all functional and there is a bit of a grinding problem with the focusing helix of one of my aluminum focusing helices. With my new lenses, I'm more concerned about the autofocus motors and the on-board electronics dying than the resin elements breaking prematurely.

[NorthernFocus]

In forty years time, my heritage glass will be 80 plus years old, and I believe still giving good service given normal care, but I will not be around to see how well the plastic throwaways have fared, and it is pointless to speculate.

You obviously don't pay attention to all the information about plastics ruining the environment because it takes them hundreds of years to degrade. Unfortunately once thrown away the plastic lenses will still be around in 80 years just like the others.