Plastic in Pentax Lenses?

**Eric Auer** · 01-13-2013, 02:53 PM

Originally posted by Adam

I've always wanted to make a video where a modern lens is dismantled, so I think we'll go ahead and find this out empirically

I'd expect a lot of the gears in a small lens to be made of plastic, though.

I'd hope that modern "Plastics" would be in there, They can stand up to abuse way better than most brass alloys.

lytrytyr · 01-13-2013, 02:54 PM

Originally posted by Adam

I'd expect a lot of the gears in a small lens to be made of plastic, though.

Based on an unplanned experiment of "Quick-Shifting" a DA L lens, I'd be inclined to agree!

lytrytyr · 01-13-2013, 02:55 PM

Originally posted by Corto-PA

I'd hope that modern "Plastics" would be in there, They can stand up to abuse way better than most brass alloys.

That's what my experiment confirmed!

**Ex Finn.** · 01-13-2013, 03:53 PM

Someone needs to do a shootout

between metal and poly-carbonate.

**Eric Auer** · 01-13-2013, 04:06 PM

Originally posted by Ex Finn.

Someone needs to do a shootout

between metal and poly-carbonate.

No Need. Self lubricating co-polymers hold up way better than surface lubricated alloys as long as the RPM's are not generating high temperatures. Smooth Focus?

But...High temperatures can be easily handled with Metal inserts in "Plastics" as Co-Polymers are non_conductive. Less friction. Not an Issue with a Lens mount.

**OrangeKx** · 01-13-2013, 04:08 PM

I don't mind the plastic, really, it helps keep the weight down.

**Eric Auer** · 01-13-2013, 04:08 PM

Originally posted by OrangeKx

I don't mind the plastic, really, it helps keep the weight down.

Amen Brother!

**arnold** · 01-13-2013, 06:47 PM - **1 Like**

Originally posted by OrangeKx

I don't mind the plastic, really, it helps keep the weight down.

There is an aesthetic factor for some of us. This can be seen in the clothes and cars we select. Drinking fine wine from a plastic cup may be practical, but hardly a complementary joy. I feel the same way about 'drinking' in scenery through a plastic lens. The joy of owning a Tacumar is the sheer quality of it's structure. I don't own a plastic watch for the same reason; mine have little metal gears in them.

vonBaloney · 01-13-2013, 06:55 PM

Originally posted by lytrytyr

Hybrid aspheric lenses have a layer of plastic added to a spherical glass element.

Note the first (left hand) element on the DA 15 Ltd diagram from Boz Dimitrov's site:

Really? Wonders never cease. Of course most eyeglasses are poly these days, that's true...

Not a Number · 01-13-2013, 07:38 PM

Originally posted by vonBaloney

Really? Wonders never cease. Of course most eyeglasses are poly these days, that's true...

Indeed! I've been wearing eyeglasses for nearly 50 years. Very few of my lenses were made of glass. My prescription now is so extreme that glasses lenses would be too thick and heavy to wear.

Camera makers started using glass filled resins in the camera and lens bodies in the late 1970s early 1980s.

When I got stuck in Hawaii during the mid 1980s for work for a lot longer than I intended I bought an auto-focus Pentax point and shoot. The owner of the store pointed out that the model I purchased still had glass lenses. The implication is that others were using plastic lenses.

I can tell you this: The very high index polycarbonate lenses cost more than either glass or some of the lower index materials for my eyeglass lenses.

So it might be a matter of cost as well as lack of acceptance by consumers for less widespread use of polycarbonate lenses.

HSV · 01-13-2013, 07:53 PM

Originally posted by lytrytyr

Based on an unplanned experiment of "Quick-Shifting" a DA L lens, I'd be inclined to agree!

What happened to the lens (after your experiment)?

Not that I haven't done it in the past, but so far I haven't damaged any lens.

John Poirier · 01-13-2013, 08:06 PM - **1 Like**

Originally posted by Corto-PA

Sorry, I was just making a point of todays "Plastic" materials and why they are quite durable.

Thanks for being reasonable.

WRT plastic in lens barrels, I was pretty skeptical about it when it first started happening. With experience I've concluded that when well done plastic is fine. Sturdy and light weight. I get a little nervous about cross-threading fllters on plastic rings, though. I also have to wonder about the effects of the solvents in DEET insect repellents on plastic barrels. I retired from mosquito country before getting new lenses, so I don't know myself. I do have some plastic bodies that have faint fingerprints from those days.

**Eric Auer** · 01-13-2013, 09:13 PM

Originally posted by John Poirier

Thanks for being reasonable.

WRT plastic in lens barrels, I was pretty skeptical about it when it first started happening. With experience I've concluded that when well done plastic is fine. Sturdy and light weight. I get a little nervous about cross-threading fllters on plastic rings, though. I also have to wonder about the effects of the solvents in DEET insect repellents on plastic barrels. I retired from mosquito country before getting new lenses, so I don't know myself. I do have some plastic bodies that have faint fingerprints from those days.

Interesting. I am a Hunter and When we have local harvest I stock my freezer. I have noticed DEET (The DeepWoods OFF brand) to be corrosive to the Blueing on my Hunting rifle and Binoculars but never thought of it messing with Polycarbonates.

Thanks for the heads up, I'll be careful not to have it on my fingers when running about with the K-5 IIs and the WR kits.

lytrytyr · 01-14-2013, 01:48 AM

Originally posted by HSV

What happened to the lens (after your experiment)?

It continued to work perfectly ever after.
Hence my response
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/211793-plastic...ml#post2239440
to Corto-PA's post.

lytrytyr · 01-14-2013, 02:10 AM

Originally posted by John Poirier

I also have to wonder about the effects of the solvents in DEET insect repellents on plastic barrels. I retired from mosquito country before getting new lenses, so I don't know myself. I do have some plastic bodies that have faint fingerprints from those days.

The Wikipedia entry on DEET says:
"DEET is an effective solvent, and may dissolve some plastics . . . and . . . varnished surfaces."

I wonder how SP coating reacts to DEET.

01-13-2013, 04:06 PM	#20
Eric Auer Site Supporter Join Date: Jul 2012 Photos: Gallery Posts: 1,211	Originally posted by Ex Finn. Someone needs to do a shootout between metal and poly-carbonate. No Need. Self lubricating co-polymers hold up way better than surface lubricated alloys as long as the RPM's are not generating high temperatures. Smooth Focus? But...High temperatures can be easily handled with Metal inserts in "Plastics" as Co-Polymers are non_conductive. Less friction. Not an Issue with a Lens mount. Last edited by Eric Auer; 01-13-2013 at 04:14 PM.

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01-13-2013, 02:53 PM	#16
Eric Auer Site Supporter Join Date: Jul 2012 Photos: Gallery Posts: 1,211	Originally posted by Adam I've always wanted to make a video where a modern lens is dismantled, so I think we'll go ahead and find this out empirically I'd expect a lot of the gears in a small lens to be made of plastic, though. I'd hope that modern "Plastics" would be in there, They can stand up to abuse way better than most brass alloys.

01-13-2013, 02:54 PM	#17
lytrytyr Pentaxian Join Date: Nov 2011 Photos: Gallery \| Albums Posts: 4,310	Originally posted by Adam I'd expect a lot of the gears in a small lens to be made of plastic, though. Based on an unplanned experiment of "Quick-Shifting" a DA L lens, I'd be inclined to agree!

01-13-2013, 02:55 PM	#18
lytrytyr Pentaxian Join Date: Nov 2011 Photos: Gallery \| Albums Posts: 4,310	Originally posted by Corto-PA I'd hope that modern "Plastics" would be in there, They can stand up to abuse way better than most brass alloys. That's what my experiment confirmed!

01-13-2013, 03:53 PM	#19
Ex Finn. Site Supporter Join Date: Nov 2007 Location: Southern Maryland. Espoo. Kouvola. Photos: Gallery \| Albums Posts: 7,975	Someone needs to do a shootout between metal and poly-carbonate.

01-13-2013, 04:08 PM	#21
OrangeKx Site Supporter Join Date: Nov 2011 Location: Vancouver, WA Photos: Gallery Posts: 817	I don't mind the plastic, really, it helps keep the weight down.

01-13-2013, 04:08 PM	#22
Eric Auer Site Supporter Join Date: Jul 2012 Photos: Gallery Posts: 1,211	Originally posted by OrangeKx I don't mind the plastic, really, it helps keep the weight down. Amen Brother!

01-13-2013, 06:47 PM - 1 Like	#23
arnold Site Supporter Join Date: Aug 2012 Location: Queensland Photos: Gallery \| Albums Posts: 4,295	Originally posted by OrangeKx I don't mind the plastic, really, it helps keep the weight down. There is an aesthetic factor for some of us. This can be seen in the clothes and cars we select. Drinking fine wine from a plastic cup may be practical, but hardly a complementary joy. I feel the same way about 'drinking' in scenery through a plastic lens. The joy of owning a Tacumar is the sheer quality of it's structure. I don't own a plastic watch for the same reason; mine have little metal gears in them.

01-13-2013, 06:55 PM	#24
vonBaloney Pentaxian Join Date: Oct 2011 Location: Albuquerque, NM Posts: 6,029	Originally posted by lytrytyr Hybrid aspheric lenses have a layer of plastic added to a spherical glass element. Note the first (left hand) element on the DA 15 Ltd diagram from Boz Dimitrov's site: Really? Wonders never cease. Of course most eyeglasses are poly these days, that's true...

01-13-2013, 07:38 PM	#25
Not a Number Moderator Join Date: Mar 2012 Location: Venice, CA Posts: 10,526	Originally posted by vonBaloney Really? Wonders never cease. Of course most eyeglasses are poly these days, that's true... Indeed! I've been wearing eyeglasses for nearly 50 years. Very few of my lenses were made of glass. My prescription now is so extreme that glasses lenses would be too thick and heavy to wear. Camera makers started using glass filled resins in the camera and lens bodies in the late 1970s early 1980s. When I got stuck in Hawaii during the mid 1980s for work for a lot longer than I intended I bought an auto-focus Pentax point and shoot. The owner of the store pointed out that the model I purchased still had glass lenses. The implication is that others were using plastic lenses. I can tell you this: The very high index polycarbonate lenses cost more than either glass or some of the lower index materials for my eyeglass lenses. So it might be a matter of cost as well as lack of acceptance by consumers for less widespread use of polycarbonate lenses.

01-13-2013, 07:53 PM	#26
HSV Veteran Member Join Date: Sep 2012 Location: Texas Posts: 321	Originally posted by lytrytyr Based on an unplanned experiment of "Quick-Shifting" a DA L lens, I'd be inclined to agree! What happened to the lens (after your experiment)? Not that I haven't done it in the past, but so far I haven't damaged any lens.

01-13-2013, 08:06 PM - 1 Like	#27
John Poirier Veteran Member Join Date: Dec 2006 Location: Gabriola Island Posts: 619	Originally posted by Corto-PA Sorry, I was just making a point of todays "Plastic" materials and why they are quite durable. Thanks for being reasonable. WRT plastic in lens barrels, I was pretty skeptical about it when it first started happening. With experience I've concluded that when well done plastic is fine. Sturdy and light weight. I get a little nervous about cross-threading fllters on plastic rings, though. I also have to wonder about the effects of the solvents in DEET insect repellents on plastic barrels. I retired from mosquito country before getting new lenses, so I don't know myself. I do have some plastic bodies that have faint fingerprints from those days.

01-13-2013, 09:13 PM	#28
Eric Auer Site Supporter Join Date: Jul 2012 Photos: Gallery Posts: 1,211	Originally posted by John Poirier Thanks for being reasonable. WRT plastic in lens barrels, I was pretty skeptical about it when it first started happening. With experience I've concluded that when well done plastic is fine. Sturdy and light weight. I get a little nervous about cross-threading fllters on plastic rings, though. I also have to wonder about the effects of the solvents in DEET insect repellents on plastic barrels. I retired from mosquito country before getting new lenses, so I don't know myself. I do have some plastic bodies that have faint fingerprints from those days. Interesting. I am a Hunter and When we have local harvest I stock my freezer. I have noticed DEET (The DeepWoods OFF brand) to be corrosive to the Blueing on my Hunting rifle and Binoculars but never thought of it messing with Polycarbonates. Thanks for the heads up, I'll be careful not to have it on my fingers when running about with the K-5 IIs and the WR kits.

01-14-2013, 01:48 AM	#29
lytrytyr Pentaxian Join Date: Nov 2011 Photos: Gallery \| Albums Posts: 4,310	Originally posted by HSV What happened to the lens (after your experiment)? It continued to work perfectly ever after. Hence my response https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/211793-plastic...ml#post2239440 to Corto-PA's post.

01-14-2013, 02:10 AM	#30
lytrytyr Pentaxian Join Date: Nov 2011 Photos: Gallery \| Albums Posts: 4,310	Originally posted by John Poirier I also have to wonder about the effects of the solvents in DEET insect repellents on plastic barrels. I retired from mosquito country before getting new lenses, so I don't know myself. I do have some plastic bodies that have faint fingerprints from those days. The Wikipedia entry on DEET says: "DEET is an effective solvent, and may dissolve some plastics . . . and . . . varnished surfaces." I wonder how SP coating reacts to DEET.