plastic lenses...why not?

[Raven]

just curious why we dont have plastic lenses?
i mean, telephoto lenses can get really heavy!
and glass can get really heavy too!
glass is also fairly expensive and VERY easy to scratch.

plastic lenses have been used in the spectacles that we wear for correcting vision.

so why cant the same technology be used for lenses on cameras?

i'm sure its a dumb question, but i'm just curious...

 

[photocist]

Glass transmits light better than plastic.

 

[Overread36]

Well there are lenses made with plastic bodies - the canon 50mm f1.8 and the (at least original that I have) EFS 18-55mm both have a plastic construction. Of course if you use plastics because they are cheap the overall durability of the product drops and I suspect that high durability plastics might not be any better/cheaper than metals. There might also be other complications to consider.

As for plastic optics plastic is just not good enough with light transmittance to really be a viable option for lenses. Yes it works on cheap glasses, but our eyes are far more adaptive and forgiving than a camera.

 

[raphaelaaron]

they suck in comparison, that's why. it's like marrying someone like angelina jolie and then cheating on her with someone like george wendt.

 

[TheBiles]

Plastic is definitely much easier to scratch than glass.

Sent from my HTC Glacier

 

[Derrel]

There have been some good lenses that used molded, aspherical, plastic elements, back in the 1980's. Due to the softness of most plastics, plastic is not typically suitable for use on external lens elements. One statement in your OP, Raven was that , "glass is also fairly expensive and VERY easy to scratch."--Uh, no, that's not accurate; modern optical-grade glass is VERY DIFFICULT to scratch, and is much more scratch-resistant than plastic or resin-based lenses.

 

[Raven]

well, i'm talking about the plastic that is used in your eye glasses that are scratch resistant, have numerous layers on them for UV and what not. are feather weight, and as such, are far better with scratches than glass.

i mean, you dont see/hear eye doctors giving you special cloth/chemical/duster/air blower etc to clean your eye glasses. a regular cotton shirt, or a tissue paper will do. however, you cant really use that on the lenses used in your camera.

 

[Overread36]

Actually I know several photographers who clean their lenses on the go with the corner of their shirt

The thing is once you've spent a few £100 to £1000 on a lens you try to treat it a lot better than a cheap pair of replaceable glasses made of plastic - hence the use of cleaning fluids and microfibre cloths. Also remember that just because you can see clear through your plastic glasses does not mean that a camera can see clear through the same plastic. There might be some that could be used for this - but costs or manufacture limits or other properties might well make it less suitable than regular optical glass.

 

[orb9220]

"a regular cotton shirt, or a tissue paper will do. however, you cant really use that on the lenses used in your camera."

Sure you can and have in a pinch myself. But not optimal due to coatings applied.
But sure if I wasn't worried about a lens lasting more than 1-3 years or costing only a couple of hundred then wouldn't be concerned so much about the issue

Just like I choose not to use filters for protecting the front element and use hoods 24/7 as the front element is a lot tougher than people credit them with.
Besides dust,scratches,little smudges have little impact on image.

I'm not promoting the idea that you shouldn't take care of your lenses and keep your equipment clean.
It's just that it doesn't have to be in top notch condition to work and take great images.
.

 

[Derrel]

well, i'm talking about the plastic that is used in your eye glasses that are scratch resistant, have numerous layers on them for UV and what not. are feather weight, and as such, are far better with scratches than glass.

i mean, you dont see/hear eye doctors giving you special cloth/chemical/duster/air blower etc to clean your eye glasses. a regular cotton shirt, or a tissue paper will do. however, you cant really use that on the lenses used in your camera.

I'm sorry Raven, but NONE of the plastic, acrylic, or resin eyeglass lenses are more scratch-resistant than optical glass. None of them. Glass is much harder than even the expensive (often a rip-off) materials being pushed at many optical shops. I've bought several pairs of the expensive, high refractive index, supposedly "durable" non-glass lenses; an old-school metal eyepiece like that found on a Nikon F2 or F3 will scratch the $h!+ out of ALL of the synthetic lenses within a few months' use; plain, garden-variety optical glass lenses are significantly more scratch-resistant. I know; I have had this discussion with two separate dispensing opticians, and anybody with any experience will tell you the same; the newer synthetics are still less scratch-resistant than plain optical glass. The coatings are only a few microns thick, and really do almost nothing to prevent scratches from any object with any momentum or mass behind it (like a camera, or a moving rock, or a scraping-across-the-surface lady's diamond ring!) I think you're greatly mistaken about the hardness of a camera lens, and how it can be [carelessly,to a point] cleaned without leaving scratches. One of the reason opticians push microfiber and suede and chamois cloths for cleaning eyeglasses is that those are made of relatively soft PLASTIC or acrylic or resin compounds, which.....ta dah...scratch easily!!!

Each lens compound has a different refractive index; glass lenses can be made with a higher refractive index than a plastic or hard resin lens, for the same thickness. Glass is more-durable, harder, and easier to work and machine/polish than the synthetics,and has a higher refractive index per thickness than even high-refractive resin. Glass has been used to make lenses for a very,very long time, but it's not all that sexy...most of it anyways...the huge mega-eyeglass chains all have their own name for hard resin, high-refractive index non-glass lenses, and to sell this overpriced, lightweight product, they have invented a lot of hype to go with it. If you think there is a resin or acrylic lens that will stand up to the rigors of a metal-eyepieced camera like the old Nikon F3-HP, I would absolutely LOVE to hear about it...

 

[Bitter Jeweler]

well, i'm talking about the plastic that is used in your eye glasses that are scratch resistant, have numerous layers on them for UV and what not. are feather weight, and as such, are far better with scratches than glass.

No, they are not.

 

[Jesse Coffman]

Even the Polycarbonate used in astronaut protection helmets will scratch before glass, although the Polycarbonate is virtually shatter resistant, and glass is generally not.

 

[usayit]

Also.... eye glasses are essentially a single element. Camera lenses are made of several elements... typically 8 or more. If stack several polycarbonate lenses and youll see an obvious degadation in image quality.


Btw... there are several toy cameras (holga too iirc) that have plastic lenses.

 

[xjoewhitex]

Plastic is definitely much easier to scratch than glass.

Sent from my HTC Glacier

Thats exactly what I was thinking.. lol

 

[cabrosh]

"Scratch resistant" plastic lens are a joke. A pair of plastic lens eyeglasses might last me a year before having too many scratches to use no matter how careful I was. Three years ago I demanded glass lenses. They're still in great shape even though I clean them with a shirttail. Glass is just a lot tougher. Who'd shell out big bucks for a camera lens that was useless in two or three years?