Can the plastic lens mount on cheap Pentax lenses be replaced?

**Aristophanes** · 06-25-2010, 08:47 PM

Originally posted by creampuff

Unlike cameras of the past which had a metal outer casing, the cameras nowadays use an internal metal skeleton that's covered by molded polycarbonate plastic shell. I faintly do recall seeing a K10D at my local Pentax service center awhile back which had it's lens mount sheared off. The screws holding the lens mount certainly didn't look like they were just screwed onto any metal frame. I figure it's robust enough for normal use but with a heavy lens mounted I don't think even a metal mount on today's cameras can withstand damage when subject to a severe shock like the camera being dropped.

Actually I'm a little disappointed that Pentax has opted for polycarbonate plastic for the lens mount on their DAL lenses. It certainly harkens back to the plethora of cheap consumer grade zoom lenses rolled out during the tenure of the previous Pentax management who came out with frankly forgettable plastic bodied film cameras that were commercial flops. Perhaps it's the dictates of the market because even however cheap the kit lens is, it is still a cost when bundled for sale with every camera body, so even a $10 saving is a lot when you're talking volume in the thousands.

I guess they feel price conscious rank newbies would either just be content to use the starter lenses blissfully ignorant of the quality difference of metal vs plastic, who also might not put these el-cheapo lenses to heavy usage and hence wear and tear (so plastic is good enough), or more likely encourage them to start buying other lenses in the lineup which have better build quality and image quality. I guess some clever Pentax executive must have reasoned that if the newbies have never used Quick Shift before, why include it. Same for putting distance markings on the DAL... it all adds up to extra cost.

After all, if people buy new lenses, that's money rolling in for Pentax, there's no money to be made if everyone stuck to kit lenses, so logically there's no compelling need to improve the build quality of the kit lenses.
I've seen the insides of the Nikon and Canon kit lenses and they are really crap. The lens elements are mostly plastic and even the aperture assembly on the Canon is a tiny little assembly. Everything is made not to last. I fear Pentax may edge closer to the slippery slope of following Canon and Nikon's lead with regards to cheapening the kit lenses.

Sorry guys but as much as plastic is good in saving weight and probably tough enuff for daily use, I'm sticking to metal. Had the el-cheapo plastic fantastic Cosina 100mm f/3.5 Macro (also comes in other guises like Phoenix, Vivitar, etc.) that was even rebadged as a Pentax. Well it's a pretty decent lens but it makes a good example of the pitfalls of going with plastic, wobbly lens barrel and all. I sold it because it always felt the lens was gonna fall apart in my hands. Looks like I'm gonna have to sell that FA J lens... FA J... J is for Junk)

I am not entirely concerned about plastic lens mounts because the mount will function most well with the least friction, and these plastics are very low friction. Furthermore, since the mount is on the lens, there's less chance of damage tot he camera body.

However, I do find the exclusion of a lens hood to be an extremely poor decision, penny wise and pound foolish, and a slap in the face both to proper respect for the front element of the lens, and a cheap way to save money by decreasing IQ for a significant % of photos.

As a marketing guy, lens hoods look cool and they are a function of design. Put 'em back!!

Laurentiu Cristofor · 06-26-2010, 10:21 AM

Originally posted by Marc Sabatella

I wonder, though, how a metal mount would have fared under the same circumstances.

Some metal lenses are so solid, you can hit them with a hammer or bang them on concrete. Here's an example:

This lens came with the hood stuck in reverse and I had to bang it a couple dozen times to detach the hood from its stuck ring. I also hammered it a few times, trying to straighten the ring. Withstood all this fine and I took some great shots with it afterwards.

Now, of course: few lenses are built like this. And the reason I had to go through all this was because the lens and hood were built so well that once they got stuck to each other, there was no way to gently separate them. The stuck hood is probably the result of an impact during shipping - how it got hit so badly is something I've never found out.

So there are disadvantages to metal too - once metal gets stuck, it's stuck for good - how many plastic hoods have been stuck on lenses?

reeftool · 06-26-2010, 12:18 PM

Metal can bend and dent, making the lens useless for all practical purposes. Also consider that over a period of time, metal to metal surfaces will wear. I suspect many of the repair guys pile of broken lenses were the result of abuse or accident. It's easy to dismiss a broken lens and say it was because of plastic but I wonder what the result would have been with the same accident and a metal lens. At work I have a lightweight 1 in. drive impact wrench that is used for truck and trailer wheels. Much of this tool is plastic and weighs half of what an all metal 1 in gun weighs and has been in constant use for 8 years. A 3/4 drive gun of similar construction failed last year after the METAL parts cracked. While it's true that there is some cheap plastic junk out there, a lot of modern plastic is incredibly strong and it doesn't corrode. Looking at a couple of my lenses, the metal lens mounts are screwed into a plastic lens housing so how strong is that?

stevebrot · 06-26-2010, 03:29 PM

Originally posted by creampuff

As we all know Pentax has done away with using a metal lens mount and using polycarbonate plastic for a number of el-cheapo consumer grade lenses as a means of saving money. Some of the cheap FA, FAJ and now DAL zoom lenses all use plastic lens mounts.

Just wondering if anybody has substituted the plastic mount with a metal one cannibalized from a dead lens? Is it even possible to retro-fit given that the pins don't look the same? I've got one el-cheapo Pentax zoom but after seeing plenty of Canon and Nikon kit lenses with broken or sheared off plastic lens mounts, I'm toying with the idea to replace the plastic mount with a metal one on my lens to make it more durable.

Good idea or not? Any thoughts?

Good idea? Hmmmm...If you have a junk donor lens AND the recipient lens you have is out of warranty AND you have access to and are handy with lens repair tools...Sure, go ahead and attempt the upgrade, document the process, and post the results here. Better yet, figure out how to do it, have somebody design/make an aftermarket upgrade/replacement K-mount kit and offer it on eBay for $30 BIN. You might even be able to follow up with Nikon and Canon versions and get rich!

OTOH...What is the real world probability of an accident damaging the mount without damaging the rest of the lens? The way I see it, the main advantage of metal over plastic is durability over time. Abrasion will have its way with plastic parts long before the same happens to stainless steel. Remember too, that the cheaper mount on the DA L lenses is the part we can see. I would suggest that the lens has many more internal parts that are lighter and less robust than the non-L version that will likely fail before the mount.

Solution for new K-x and K-m (K2000) buyers? Don't buy the two lens kit. Negotiate with the dealer for an upgrade to the non-L version of the 18-55 at time of purchase. That failing, use your DA L lens until you break it or it wears out and then replace it with something better.

Steve

MellowJ · 12-30-2010, 04:28 PM

I have a broken tab on the mount of my 55-300 DA L. I'd like to replace it with a metal mount. I can't see why everyone seems to think why this is a non-issue? I doubt very much I would have a broken tab if the current was not plastic.

If anyone has a metal mount available - even from a manual lens that I could retrofit - please let me know.

Blue · 12-30-2010, 05:07 PM

Originally posted by MellowJ

I have a broken tab on the mount of my 55-300 DA L. I'd like to replace it with a metal mount. I can't see why everyone seems to think why this is a non-issue? I doubt very much I would have a broken tab if the current was not plastic.

If anyone has a metal mount available - even from a manual lens that I could retrofit - please let me know.

The F and FA 35-80mm lenses are "Dogs" in every since of the word, optically speaking. I would get one of those and give it a try. I don't have any af zooms around to rogue so If I were in your situation, I would pick up something like this from KEH and try it.

Pentax Autofocus 35-80 F4-5.6 SMC F (49) 35MM SLR AUTO FOCUS ZOOM WIDE ANGLE LENS - KEH.com

Since you are in Oregon, you may be able to go by Blue Moon Camera and Machine and see if they have an af lens worth sacrificing. It doesn't necessarily have to be a zoom as long as its AF.

Blue Moon Camera and Machine
8417 North Lombard Street
Portland, Oregon 97203

Contact Blue Moon Camera and Machine, Portland, OR

Maybe you will get lucky and someone that reads this will have an old af lens around.

tibbitts · 12-30-2010, 06:23 PM

Originally posted by MellowJ

I have a broken tab on the mount of my 55-300 DA L. I'd like to replace it with a metal mount. I can't see why everyone seems to think why this is a non-issue? I doubt very much I would have a broken tab if the current was not plastic.

If anyone has a metal mount available - even from a manual lens that I could retrofit - please let me know.

What caused the tab to break? If from impact, it might have have torn the mount out of the body if you'd had a metal mount, even assuming the metal mount was stronger.

I have a metal mount on the 16-45mm DA. But much of the rest of the lens is plastic. There's an incredible amount of play in the barrel, especially with the lens extended to 16mm. So maybe people just feel that the plastic mount isn't necessarily a weak link in the overall scheme.

Paul

Blue · 12-30-2010, 06:29 PM - **1 Like**

Originally posted by tibbitts

What caused the tab to break? If from impact, it might have have torn the mount out of the body if you'd had a metal mount, even assuming the metal mount was stronger.

I have a metal mount on the 16-45mm DA. But much of the rest of the lens is plastic. There's an incredible amount of play in the barrel, especially with the lens extended to 16mm. So maybe people just feel that the plastic mount isn't necessarily a weak link in the overall scheme.

Paul

Problem solved. Trade him the metal mount of your 16-45mm for his plastic mount of the DA L 55-300mm.

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06-25-2010, 08:47 PM	#16
Aristophanes Site Supporter Join Date: Jul 2008 Location: Rankin Inlet, Nunavut Photos: Albums Posts: 3,948	Originally posted by creampuff Unlike cameras of the past which had a metal outer casing, the cameras nowadays use an internal metal skeleton that's covered by molded polycarbonate plastic shell. I faintly do recall seeing a K10D at my local Pentax service center awhile back which had it's lens mount sheared off. The screws holding the lens mount certainly didn't look like they were just screwed onto any metal frame. I figure it's robust enough for normal use but with a heavy lens mounted I don't think even a metal mount on today's cameras can withstand damage when subject to a severe shock like the camera being dropped. Actually I'm a little disappointed that Pentax has opted for polycarbonate plastic for the lens mount on their DAL lenses. It certainly harkens back to the plethora of cheap consumer grade zoom lenses rolled out during the tenure of the previous Pentax management who came out with frankly forgettable plastic bodied film cameras that were commercial flops. Perhaps it's the dictates of the market because even however cheap the kit lens is, it is still a cost when bundled for sale with every camera body, so even a $10 saving is a lot when you're talking volume in the thousands. I guess they feel price conscious rank newbies would either just be content to use the starter lenses blissfully ignorant of the quality difference of metal vs plastic, who also might not put these el-cheapo lenses to heavy usage and hence wear and tear (so plastic is good enough), or more likely encourage them to start buying other lenses in the lineup which have better build quality and image quality. I guess some clever Pentax executive must have reasoned that if the newbies have never used Quick Shift before, why include it. Same for putting distance markings on the DAL... it all adds up to extra cost. After all, if people buy new lenses, that's money rolling in for Pentax, there's no money to be made if everyone stuck to kit lenses, so logically there's no compelling need to improve the build quality of the kit lenses. I've seen the insides of the Nikon and Canon kit lenses and they are really crap. The lens elements are mostly plastic and even the aperture assembly on the Canon is a tiny little assembly. Everything is made not to last. I fear Pentax may edge closer to the slippery slope of following Canon and Nikon's lead with regards to cheapening the kit lenses. Sorry guys but as much as plastic is good in saving weight and probably tough enuff for daily use, I'm sticking to metal. Had the el-cheapo plastic fantastic Cosina 100mm f/3.5 Macro (also comes in other guises like Phoenix, Vivitar, etc.) that was even rebadged as a Pentax. Well it's a pretty decent lens but it makes a good example of the pitfalls of going with plastic, wobbly lens barrel and all. I sold it because it always felt the lens was gonna fall apart in my hands. Looks like I'm gonna have to sell that FA J lens... FA J... J is for Junk) I am not entirely concerned about plastic lens mounts because the mount will function most well with the least friction, and these plastics are very low friction. Furthermore, since the mount is on the lens, there's less chance of damage tot he camera body. However, I do find the exclusion of a lens hood to be an extremely poor decision, penny wise and pound foolish, and a slap in the face both to proper respect for the front element of the lens, and a cheap way to save money by decreasing IQ for a significant % of photos. As a marketing guy, lens hoods look cool and they are a function of design. Put 'em back!!

06-26-2010, 10:21 AM	#17
Laurentiu Cristofor Banned Join Date: Nov 2009 Location: WA Photos: Albums Posts: 3,055	Originally posted by Marc Sabatella I wonder, though, how a metal mount would have fared under the same circumstances. Some metal lenses are so solid, you can hit them with a hammer or bang them on concrete. Here's an example: This lens came with the hood stuck in reverse and I had to bang it a couple dozen times to detach the hood from its stuck ring. I also hammered it a few times, trying to straighten the ring. Withstood all this fine and I took some great shots with it afterwards. Now, of course: few lenses are built like this. And the reason I had to go through all this was because the lens and hood were built so well that once they got stuck to each other, there was no way to gently separate them. The stuck hood is probably the result of an impact during shipping - how it got hit so badly is something I've never found out. So there are disadvantages to metal too - once metal gets stuck, it's stuck for good - how many plastic hoods have been stuck on lenses?

06-26-2010, 12:18 PM	#18
reeftool Pentaxian Join Date: Dec 2007 Location: Upstate New York Photos: Gallery \| Albums Posts: 9,555	Metal can bend and dent, making the lens useless for all practical purposes. Also consider that over a period of time, metal to metal surfaces will wear. I suspect many of the repair guys pile of broken lenses were the result of abuse or accident. It's easy to dismiss a broken lens and say it was because of plastic but I wonder what the result would have been with the same accident and a metal lens. At work I have a lightweight 1 in. drive impact wrench that is used for truck and trailer wheels. Much of this tool is plastic and weighs half of what an all metal 1 in gun weighs and has been in constant use for 8 years. A 3/4 drive gun of similar construction failed last year after the METAL parts cracked. While it's true that there is some cheap plastic junk out there, a lot of modern plastic is incredibly strong and it doesn't corrode. Looking at a couple of my lenses, the metal lens mounts are screwed into a plastic lens housing so how strong is that?

06-26-2010, 03:29 PM	#19
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by creampuff As we all know Pentax has done away with using a metal lens mount and using polycarbonate plastic for a number of el-cheapo consumer grade lenses as a means of saving money. Some of the cheap FA, FAJ and now DAL zoom lenses all use plastic lens mounts. Just wondering if anybody has substituted the plastic mount with a metal one cannibalized from a dead lens? Is it even possible to retro-fit given that the pins don't look the same? I've got one el-cheapo Pentax zoom but after seeing plenty of Canon and Nikon kit lenses with broken or sheared off plastic lens mounts, I'm toying with the idea to replace the plastic mount with a metal one on my lens to make it more durable. Good idea or not? Any thoughts? Good idea? Hmmmm...If you have a junk donor lens AND the recipient lens you have is out of warranty AND you have access to and are handy with lens repair tools...Sure, go ahead and attempt the upgrade, document the process, and post the results here. Better yet, figure out how to do it, have somebody design/make an aftermarket upgrade/replacement K-mount kit and offer it on eBay for $30 BIN. You might even be able to follow up with Nikon and Canon versions and get rich! OTOH...What is the real world probability of an accident damaging the mount without damaging the rest of the lens? The way I see it, the main advantage of metal over plastic is durability over time. Abrasion will have its way with plastic parts long before the same happens to stainless steel. Remember too, that the cheaper mount on the DA L lenses is the part we can see. I would suggest that the lens has many more internal parts that are lighter and less robust than the non-L version that will likely fail before the mount. Solution for new K-x and K-m (K2000) buyers? Don't buy the two lens kit. Negotiate with the dealer for an upgrade to the non-L version of the 18-55 at time of purchase. That failing, use your DA L lens until you break it or it wears out and then replace it with something better. Steve

12-30-2010, 04:28 PM	#20
MellowJ New Member Join Date: Nov 2009 Location: Oregon Posts: 8	I have a broken tab on the mount of my 55-300 DA L. I'd like to replace it with a metal mount. I can't see why everyone seems to think why this is a non-issue? I doubt very much I would have a broken tab if the current was not plastic. If anyone has a metal mount available - even from a manual lens that I could retrofit - please let me know.

12-30-2010, 05:07 PM	#21
Blue Moderator Site Supporter Join Date: Jun 2008 Location: Florida Hill Country Photos: Gallery \| Albums Posts: 17,377	Originally posted by MellowJ I have a broken tab on the mount of my 55-300 DA L. I'd like to replace it with a metal mount. I can't see why everyone seems to think why this is a non-issue? I doubt very much I would have a broken tab if the current was not plastic. If anyone has a metal mount available - even from a manual lens that I could retrofit - please let me know. The F and FA 35-80mm lenses are "Dogs" in every since of the word, optically speaking. I would get one of those and give it a try. I don't have any af zooms around to rogue so If I were in your situation, I would pick up something like this from KEH and try it. Pentax Autofocus 35-80 F4-5.6 SMC F (49) 35MM SLR AUTO FOCUS ZOOM WIDE ANGLE LENS - KEH.com Since you are in Oregon, you may be able to go by Blue Moon Camera and Machine and see if they have an af lens worth sacrificing. It doesn't necessarily have to be a zoom as long as its AF. Blue Moon Camera and Machine 8417 North Lombard Street Portland, Oregon 97203 Contact Blue Moon Camera and Machine, Portland, OR Maybe you will get lucky and someone that reads this will have an old af lens around.

12-30-2010, 06:23 PM	#22
tibbitts Pentaxian Join Date: Apr 2007 Location: Oklahoma USA Posts: 2,196	Originally posted by MellowJ I have a broken tab on the mount of my 55-300 DA L. I'd like to replace it with a metal mount. I can't see why everyone seems to think why this is a non-issue? I doubt very much I would have a broken tab if the current was not plastic. If anyone has a metal mount available - even from a manual lens that I could retrofit - please let me know. What caused the tab to break? If from impact, it might have have torn the mount out of the body if you'd had a metal mount, even assuming the metal mount was stronger. I have a metal mount on the 16-45mm DA. But much of the rest of the lens is plastic. There's an incredible amount of play in the barrel, especially with the lens extended to 16mm. So maybe people just feel that the plastic mount isn't necessarily a weak link in the overall scheme. Paul

12-30-2010, 06:29 PM - 1 Like	#23
Blue Moderator Site Supporter Join Date: Jun 2008 Location: Florida Hill Country Photos: Gallery \| Albums Posts: 17,377	Originally posted by tibbitts What caused the tab to break? If from impact, it might have have torn the mount out of the body if you'd had a metal mount, even assuming the metal mount was stronger. I have a metal mount on the 16-45mm DA. But much of the rest of the lens is plastic. There's an incredible amount of play in the barrel, especially with the lens extended to 16mm. So maybe people just feel that the plastic mount isn't necessarily a weak link in the overall scheme. Paul Problem solved. Trade him the metal mount of your 16-45mm for his plastic mount of the DA L 55-300mm.