Addressing a Bent Filter Thread (Pentax 105mm 2.4 SMC)

jchabalk · 04-13-2021, 05:57 PM

I just received a 105 2.4 i bought on eBay. It had all of the superfluous descriptors of being mint ++++++ and all that - which seems to be getting out of hand lately on these photo auctions.

Overall this lens is in great shape - except...

There's a small mark on the front ring
That small mark is actually a small dent
The small dent makes it nearly impossible to put a filter on it, or otherwise use the front ring.

I contacted the seller about it but i'm wondering if this is a easily fixable issue or if i'm asking for trouble with it. Basically i'm looking to keep the lens and want to get it fixed.

I've bought and sold a ton of camera gear on ebay over the years and have been through this sort of thing a number of times, but this is my first nearly invisible bent filter ring on an otherwise flawless lens.

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**jon.partsch** · 04-13-2021, 06:34 PM

There is a tool commonly called a "filter ring vise" that is intended to correct this specific and common damage. I don't know how well they work as I have never tried one.

jchabalk · 04-13-2021, 06:54 PM

I've seen those before. I was out looking around for one and came across what might be a couple of options - if anyone has used one successfully i'd love to hear about it.

This particular one is sold under a bunch of different names from a bunch of different places. It looks like it's made of aluminum stock and on a burly lens like one of these pentax lenses from the 70s it seems like the lens might out muscle the vice tool. I'm sure it would work well enough the first time.

There's this other one i found that's probably not steel but is maybe zinc - it seems more robust anyway. It also costs more and claims to cover a small diameter range of lenses.

**Eric Auer** · 04-13-2021, 07:39 PM - **1 Like**

If it can take a filter at all, put an extension or step up ring on it and call it a day.

I have straightened out dented lenses with pliers and home made nylon pads, but not for the faint of heart.

**DonV** · 04-13-2021, 07:55 PM

What Eric said; I'd add a little silicone grease when screwing a step ring into your very slightly dented filter ring, it will probably iron it out.
Use a step up ring for a little better grip and control.

Yes, the tools work, but are primarily for a "worse" dent; even after their use you will have a "rough" spot and need to do the above. I have the second one, it works; but not as good as you might hope for that small dent.
Apply too much pressure, and you wind up it a bump "out" instead on an "in" dent.

All those "exc++++" seem to originate in Japan; they are essentially meaningless. I've read a couple of those descriptions, and found in the details something like "thin haze on the middle element" !

Not a Number · 04-13-2021, 08:19 PM - **1 Like**

See this thread:
Multiple dents in SMC-A 24-50/4 filter thread repaired - PentaxForums.com

**jumbleview** · 04-13-2021, 10:03 PM

I had similar problem with Takumar 105 lens. I bought this tool:
amazon.com: Neewer Camera Lens Vise Repair Tool for Lens and Filter, Ring Adjustment Range 27mm to 130mm, Steel Construction: Everything Else?tag=pentaxforums-20&
There are some videos on Youtube how to work with it. Dent on mine was really strong. I could not make it perfect but I can put filter on it no.

LensBeginner · 04-14-2021, 01:40 AM - **1 Like**

The filter issue looks trivial to me; what doesn't is the fact that it probably originated from a fall or a bang.
Since this one is an all-metal vintage Pentax lens, the chances something went out of place are less than if it were an all-plastic modern thing, still I would check thoroughly to see if something's out of whack.

**K(s)evin** · 04-14-2021, 02:00 AM - **1 Like**

Originally posted by jumbleview

I had similar problem with Takumar 105 lens. I bought this tool:
amazon.com: Neewer Camera Lens Vise Repair Tool for Lens and Filter, Ring Adjustment Range 27mm to 130mm, Steel Construction: Everything Else?tag=pentaxforums-20&
There are some videos on Youtube how to work with it. Dent on mine was really strong. I could not make it perfect but I can put filter on it no.

This^^^^^ works very well.

**Ed Hurst** · 04-14-2021, 02:57 AM

Originally posted by LensBeginner

The filter issue looks trivial to me; what doesn't is the fact that it probably originated from a fall or a bang.
Since this one is an all-metal vintage Pentax lens, the chances something went out of place are less than if it were an all-plastic modern thing, still I would check thoroughly to see if something's out of whack.

This would be my concern too!

kypfer · 04-14-2021, 03:26 AM

A solution I read about on "the web" and tried for myself involves resting the dented part of the lens thread on a thick pad of "Blu-Tac", "poster putty" or similar then wacking the inside of the dent with a wooden stick and a hammer! Sounds brutal, but it works perfectly if the only distortion is lateral and minimal
In the event of longitudinal distortion, I've reverted to de-glassing a suitably sized filter, filing off the male threads and gluing this into position, for a slightly extended but perfectly serviceable replacement thread.

Neither solution is for the faint-hearted or for a lens of any significant re-sale value

**Eric Auer** · 04-14-2021, 04:46 AM

Originally posted by LensBeginner

The filter issue looks trivial to me; what doesn't is the fact that it probably originated from a fall or a bang.
Since this one is an all-metal vintage Pentax lens, the chances something went out of place are less than if it were an all-plastic modern thing, still I would check thoroughly to see if something's out of whack.

Originally posted by Ed Hurst

This would be my concern too!

That's a tiny dent guys. Have a little more faith..

**pentaxus** · 04-14-2021, 07:50 AM

The wooden stick and hammer works very well for this size ding. The spreader pushes the other side of the lens and for bigger dents the other side gets pushed out.

MJKoski · 04-14-2021, 08:45 AM

That filter ring vise -tool seems very usable. Thank you for linking it. I have one dented filter ring one one old Zeiss lens.

**Eric Auer** · 04-14-2021, 10:04 AM

Originally posted by pentaxus

The wooden stick and hammer works very well for this size ding. The spreader pushes the other side of the lens and for bigger dents the other side gets pushed out.

I thought about that for a while, and wonder how much force it takes to possibly get the front of the lens out of round?

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04-13-2021, 06:34 PM	#2
jon.partsch Site Supporter Join Date: Oct 2009 Location: Northern California Posts: 442	There is a tool commonly called a "filter ring vise" that is intended to correct this specific and common damage. I don't know how well they work as I have never tried one.

04-13-2021, 06:54 PM	#3
jchabalk Junior Member Join Date: Apr 2021 Posts: 29 Original Poster	I've seen those before. I was out looking around for one and came across what might be a couple of options - if anyone has used one successfully i'd love to hear about it. This particular one is sold under a bunch of different names from a bunch of different places. It looks like it's made of aluminum stock and on a burly lens like one of these pentax lenses from the 70s it seems like the lens might out muscle the vice tool. I'm sure it would work well enough the first time. There's this other one i found that's probably not steel but is maybe zinc - it seems more robust anyway. It also costs more and claims to cover a small diameter range of lenses.

04-13-2021, 07:39 PM - 1 Like	#4
Eric Auer Site Supporter Join Date: Jul 2012 Photos: Gallery Posts: 1,211	If it can take a filter at all, put an extension or step up ring on it and call it a day. I have straightened out dented lenses with pliers and home made nylon pads, but not for the faint of heart.

04-13-2021, 07:55 PM	#5
DonV Site Supporter Join Date: Jan 2017 Location: Near Charlotte NC Photos: Albums Posts: 693	What Eric said; I'd add a little silicone grease when screwing a step ring into your very slightly dented filter ring, it will probably iron it out. Use a step up ring for a little better grip and control. Yes, the tools work, but are primarily for a "worse" dent; even after their use you will have a "rough" spot and need to do the above. I have the second one, it works; but not as good as you might hope for that small dent. Apply too much pressure, and you wind up it a bump "out" instead on an "in" dent. All those "exc++++" seem to originate in Japan; they are essentially meaningless. I've read a couple of those descriptions, and found in the details something like "thin haze on the middle element" !

04-13-2021, 08:19 PM - 1 Like	#6
Not a Number Moderator Join Date: Mar 2012 Location: Venice, CA Posts: 10,526	See this thread: Multiple dents in SMC-A 24-50/4 filter thread repaired - PentaxForums.com

04-13-2021, 10:03 PM	#7
jumbleview Site Supporter Join Date: May 2012 Location: Concord, CA Posts: 1,069	I had similar problem with Takumar 105 lens. I bought this tool: amazon.com: Neewer Camera Lens Vise Repair Tool for Lens and Filter, Ring Adjustment Range 27mm to 130mm, Steel Construction: Everything Else?tag=pentaxforums-20& There are some videos on Youtube how to work with it. Dent on mine was really strong. I could not make it perfect but I can put filter on it no.

04-14-2021, 01:40 AM - 1 Like	#8
LensBeginner Veteran Member Join Date: Sep 2014 Photos: Albums Posts: 4,696	The filter issue looks trivial to me; what doesn't is the fact that it probably originated from a fall or a bang. Since this one is an all-metal vintage Pentax lens, the chances something went out of place are less than if it were an all-plastic modern thing, still I would check thoroughly to see if something's out of whack.

04-14-2021, 02:00 AM - 1 Like	#9
K(s)evin Site Supporter Join Date: Sep 2010 Location: Colorado Posts: 476	Originally posted by jumbleview I had similar problem with Takumar 105 lens. I bought this tool: amazon.com: Neewer Camera Lens Vise Repair Tool for Lens and Filter, Ring Adjustment Range 27mm to 130mm, Steel Construction: Everything Else?tag=pentaxforums-20& There are some videos on Youtube how to work with it. Dent on mine was really strong. I could not make it perfect but I can put filter on it no. This^^^^^ works very well.

04-14-2021, 02:57 AM	#10
Ed Hurst Site Supporter Join Date: May 2010 Location: Sydney Posts: 1,657	Originally posted by LensBeginner The filter issue looks trivial to me; what doesn't is the fact that it probably originated from a fall or a bang. Since this one is an all-metal vintage Pentax lens, the chances something went out of place are less than if it were an all-plastic modern thing, still I would check thoroughly to see if something's out of whack. This would be my concern too!

04-14-2021, 03:26 AM	#11
kypfer Pentaxian Join Date: Jan 2018 Location: Jersey C.I. Posts: 3,593	A solution I read about on "the web" and tried for myself involves resting the dented part of the lens thread on a thick pad of "Blu-Tac", "poster putty" or similar then wacking the inside of the dent with a wooden stick and a hammer! Sounds brutal, but it works perfectly if the only distortion is lateral and minimal In the event of longitudinal distortion, I've reverted to de-glassing a suitably sized filter, filing off the male threads and gluing this into position, for a slightly extended but perfectly serviceable replacement thread. Neither solution is for the faint-hearted or for a lens of any significant re-sale value

04-14-2021, 04:46 AM	#12
Eric Auer Site Supporter Join Date: Jul 2012 Photos: Gallery Posts: 1,211	Originally posted by LensBeginner The filter issue looks trivial to me; what doesn't is the fact that it probably originated from a fall or a bang. Since this one is an all-metal vintage Pentax lens, the chances something went out of place are less than if it were an all-plastic modern thing, still I would check thoroughly to see if something's out of whack. Originally posted by Ed Hurst This would be my concern too! That's a tiny dent guys. Have a little more faith..

04-14-2021, 07:50 AM	#13
pentaxus Site Supporter Join Date: Jun 2010 Location: Central Coast, CA Posts: 1,313	The wooden stick and hammer works very well for this size ding. The spreader pushes the other side of the lens and for bigger dents the other side gets pushed out.

04-14-2021, 08:45 AM	#14
MJKoski Veteran Member Join Date: Aug 2016 Posts: 1,784	That filter ring vise -tool seems very usable. Thank you for linking it. I have one dented filter ring one one old Zeiss lens.

04-14-2021, 10:04 AM	#15
Eric Auer Site Supporter Join Date: Jul 2012 Photos: Gallery Posts: 1,211	Originally posted by pentaxus The wooden stick and hammer works very well for this size ding. The spreader pushes the other side of the lens and for bigger dents the other side gets pushed out. I thought about that for a while, and wonder how much force it takes to possibly get the front of the lens out of round?