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02-11-2016, 07:56 AM   #16
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I can't say anything about this now, but I read about this some time ago and found it interesting...

02-11-2016, 08:02 AM   #17
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Back in the 60's my photography teacher asked what his favourite camera was, said it was some cheap throw away he had in his glove compartment, because it was always handy, and the cheap lenses were parabolic plastic, giving much wider DoF than glass lenses.

Plastic lenses have had their uses for a very long time. I didn't know about the plastic elements in Pentax lenses , so I've always wondered why they didn't have plastic elements. There has been optical grades of plastic since the 60's. I fully expected there to be more completely plastic lenses by now. I guess glass still has some advantages, despite 50 years of development.
02-11-2016, 08:35 AM - 3 Likes   #18
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Saying something is "plastic" really doesn't tell you much about the material. Glass is "plastic", in the sense of being moldable or shapable. When I took materials science, we had to identify the plastic in a part using a catalog of polymers that was a couple inches thick - there were tens of thousands of different kinds of "plastic". Unfortunately, "plastic" has a popular meaning of "cheap and disposable", thanks to polystyrene toys and polyethylene bottles and bags. I have lenses less old than I am with metal parts that are oxidizing and crumbling - "metal" doesn't always mean durable. I have Bakelite (plastic) castings that are much older than I am, and look like new. What matters is what kind of metal, glass, or plastic is used, whether it is appropriate for the job, and whether it is manufactured correctly. For modern lenses, the electronics, motors, and gearing will probably fail long, long before the optical elements, whether glass or plastic.

Last edited by THoog; 02-11-2016 at 09:33 AM. Reason: typo
02-11-2016, 09:23 AM   #19
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I was a product design engineer for many years. There are literally tens of thousands of different formulations of 'plastic', a very broad term. I have been a fan of polycarbonate for a long time for its various properties. Having said that, I was SHOCKED when I found out that a Nikon camera my company bought had a plastic front lens element. How could you possibly clean it without scratching it? A highly respected brand resorting to cheap components? Where's Rod Serling; is this the Twilight Zone? After that emotional knee-jerk reaction, my designer brain took over. Molds for plastic can be polished to a 4 micro-inch finish or better, yielding mirror-smooth surfaces. Certain formulations of polycarbonate are specifically designed for their optical qualities. And, todays nano crystal coatings are sufficiently advanced to provide excellent hardness and abrasion resistance for front lens elements. As mentioned by others, plastic lenses can be made with very complex curvatures to optimize optical design more quickly and inexpensively than a glass element could be. I'm old school too, but I'm now convinced that 'plastic' isn't necessarily inferior.

QuoteOriginally posted by Rupert Quote
my only concern is that plastic tends to attract dust particles because it will hold a charge well
Hoya offers filters that have an anti-static coating. Kenko Tokina USA, Inc. These filters are glass, but perhaps the technology could be (or has been) adapted to plastic lens coatings as well. I believe that most plastic lens elements are inside the barrel where dust attraction is not much of an issue (especially with Pentax's WR sealing lens designs). I can't comment on the dust attraction of the Nikon front lens element because I didn't like the camera and decided not to use it.

02-11-2016, 10:03 AM   #20
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you could make crown elements out of polyethylene terephthalate (soda bottles) and with a bit of germanium dioxide (used to modify refractive index) mixed in with the polyethylene terephthalate you can make your flint glass

reason why plumbers back in the day didn't trust plastic was because of phenol-formaldehyde (more commonly known as bakelite) gave plastic a bad name, everything was made from this stuff in the 1940's it would turn chalky over time and eventually fall apart

my fav camera is the vivitar wide and slim with its plastic 22mm lens
02-11-2016, 11:06 AM   #21
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Lenses? Well, OK. Molded aspherical optics may beat impossible to grind/polish glass shapes in some applications.

But plastic cars, boats and aircraft? Mmmm, ya gotta think twice there!
02-11-2016, 11:07 AM   #22
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QuoteOriginally posted by Ratcheteer Quote
my fav camera is the vivitar wide and slim with its plastic 22mm lens
I have one too - great little camera!
02-11-2016, 11:18 AM   #23
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I think this is one of those times when not being a gearhead has advantages. You only let the plastic bother you because you know of it.

02-11-2016, 11:33 AM   #24
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QuoteOriginally posted by pacerr Quote
But plastic cars, boats and aircraft? Mmmm, ya gotta think twice there!
I have a plastic boat. It folds up

Porta Bote | The Revolutionary Folding Boat
02-11-2016, 11:34 AM   #25
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QuoteOriginally posted by starbase218 Quote
I think this is one of those times when not being a gearhead has advantages. You only let the plastic bother you because you know of it.
Probably more applicable to gear snobs, I'm as gear heady as any gear head, but, I've known about optical plastics for 50 years and am more excited that they've made their way into high end lenses. And especially since lens rentals pointed out that plastic lens barrels are more practical than metal, and much cheaper to repair if dropped based on the damage incurred to the various components.

A true gear head, looks at the numbers, probably much like a high end designer does and makes a choice, what's the best material for this application. Gear snobs are caught up in having reasons for putting down other people's gear. It's too funny on the various sites, many people have put down plastic in lenses and gone with the "I'm a purist" tack, only to find out their favourite lens has plastic components in it. Anyone planning to go down that path, might want to thoroughly research the topic first.

---------- Post added 02-11-16 at 01:45 PM ----------

QuoteOriginally posted by boriscleto Quote
I have a plastic boat. It folds up

Porta Bote | The Revolutionary Folding Boat
I started canoe tripping with Coleman poly-ethylene canoes. The thing is, if you're new to tripping and need to work on your skills, a Coleman boat is a fantastic thing. If you start your trip with a Coleman boat, you'll finish the trip with the same boat. Short of throwing it on your campfire, there's nothing you can do that is going to destroy it or make it less seaworthy.

Last edited by normhead; 02-11-2016 at 11:45 AM.
02-11-2016, 11:55 AM   #26
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QuoteOriginally posted by pacerr Quote
But plastic cars, boats and aircraft? Mmmm, ya gotta think twice there!
Um, isn't carbon fiber, fiberglass, composites, etc. all part of the plastic group? Formula One and fighter jets thus have a lot of plastic in it.

I found it amusing when the textile industry dropped Nylon and embraced Polyamide 6.6 as the wonder fabric. Chemically identical, it didn't have the cheap and nasty connotation.
02-11-2016, 12:04 PM   #27
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QuoteOriginally posted by pacerr Quote
Lenses? Well, OK. Molded aspherical optics may beat impossible to grind/polish glass shapes in some applications.
nah you press it into shape then center the lens on a rig that looks like a turntable, it would spin then a arm reminiscent of a actual tone arm but with a oscillating brush would move then squirt a substance onto the lens that looks a little bit like toothpaste then would proceed to polish it for you :P
02-11-2016, 12:25 PM   #28
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QuoteOriginally posted by pacerr Quote
Mmmm, ya gotta think twice there!
Can't quite see the tongue-in-cheek, huh?
02-11-2016, 12:48 PM   #29
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QuoteOriginally posted by Timd Quote
Um, isn't carbon fiber, fiberglass, composites, etc. all part of the plastic group? Formula One and fighter jets thus have a lot of plastic in it.
Composites are a fourth group, as they contain mixtures of polymers ("plastics"), ceramics, and metals. What we call "fiberglass" is a matrix of glass fibers, bonded together with a polymer (usually polyester resin). "Carbon fiber" is similar, just with graphite fibers instead of glass fibers, but still bonded together with a polymer resin. Another common composite is "epoxy putty", a combination of epoxy resin and a filler, which can be powdered ceramic. If you are familiar with "JB Weld", it's epoxy resin with powdered iron as one of the fillers. "Cold cast porcelain" is yet another example of a polymer resin with ceramic filler.

(I'm actually a computer/electrical engineer, but I really enjoyed that materials science class. I've probably used it more in hobbies than in work. )
02-11-2016, 02:20 PM   #30
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I have numerous intraocular implants to control glaucoma. Parts of these implants are polycarbonate. My intraocular lenses are flexible acrylic. Older IOL's were PMMA (rigid polymethylmethacrylate).

If plastic is good enough to see through it's good enough for optics.
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