Tokina 500mm Mirror Lens Focus Locked

**longbo** · 08-23-2021, 04:37 AM

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I've had a copy of this lens for a while and it was fine last time I used it, but when I got it out to try it on my K3-3, I found that the focus ring was completely seized - not even the slightest movement. The lens has been in a drawer since last used, so it's not been dropped or otherwise abused.

Does anyone know what might have happened to it? Any ideas about disassembly to fix it? - I can't see it being worth paying to get it fixed, when similar models are available on eBay for £60 or so.

Last edited by longbo; 08-23-2021 at 07:50 AM.

mlynch53 · 08-23-2021, 06:22 AM

longbo,

I also have a Tokina 500mm mirror lens for my Pentax DSLR, and I've never had something like this happen.

But to make sure we're talking about the same lens ... On mine, the barrel turns for focus (and it does so very smoothly).

You use the term "focus ring" in your original message. Does yours, in fact, have a "ring," or does the barrel turn for focus?

Mike

**longbo** · 08-23-2021, 07:37 AM

Mike, sorry, loose terminology - it's the barrel. Mine too was very smooth - until now!

**longbo** · 08-23-2021, 10:39 AM

I posted this query in the Dslr Lens Forum, but it struck me that it might be more relevant here, as I'm asking about a problem. If it's not allowed to post in two different fora, my apologies.

I've had a copy of the Tokina 500mm Mirror lens for some time, but it's not been used for a while. I got it out to try on my K3-3, but found that the focusing mechanism was locked solid - no movement of the focusing barrel at all. The lens was fine when last used and since then has been in a drawer, so not been dropped or otherwise abused.

Can anyone advise what might have happened to it? Does anyone have any disassembly instructions, so I can try a fix?

**Bob 256** · 08-23-2021, 12:31 PM

It might be the lubricant has dried up. One thing you might try is placing the lens in the sun to gently warm it and see if it loosens up (don't let it get scorching hot!). Sometimes you can get it moving that way and redistribute some good lubricant to get it functional. Otherwise it might be a repair job. Could be something got in the helical in which case, the only solution is to disassemble the lens - sorry can't help you there.

**longbo** · 08-23-2021, 02:13 PM

Originally posted by Bob 256

It might be the lubricant has dried up. One thing you might try is placing the lens in the sun to gently warm it and see if it loosens up (don't let it get scorching hot!). Sometimes you can get it moving that way and redistribute some good lubricant to get it functional. Otherwise it might be a repair job. Could be something got in the helical in which case, the only solution is to disassemble the lens - sorry can't help you there.

Thanks. I've tried gently warming it with no luck. I'll try a bit more heat and see if that helps. I don't think a professional repair is realistic as eBay has these lenses starting at £60. I'm just hoping someone may know how to get it apart!

Not a Number · 08-23-2021, 03:24 PM

Duplicate threads are discouraged by the Forum Rules and Guidelines. Questions like these on a specific lens are a toss-up between the lens discussion or trouble shooting forums. Pick one and stick with it in the future. The moderating staff may decide one or the other forums is better than the other and move the threads. Redundant threads are either closed, deleted or merged.

**.a.t.** · 08-23-2021, 04:34 PM

Originally posted by longbo

Thanks. I've tried gently warming it with no luck. I'll try a bit more heat and see if that helps. I don't think a professional repair is realistic as eBay has these lenses starting at £60. I'm just hoping someone may know how to get it apart!

On my (Sears branded) copy, there are four screws at the upper end of the distance scale which bind it to the focus barrel. When those screws are loosened, the distance scale will drop down and the focus barrel can unscrew from the lower half of the lens.

Unless the barrel is stuck!
I'm not sure what to recommend other than more heat..?

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Name: IMGP2360 g crop 12.jpg
Views: 143
Size: 141.7 KB

The screws to loosen (orange circle) can be accessed without lifting up the rubber focus grip. But my lens had lacquer on the barrel under the grip. The lacquer was joining the distance scale and focus barrel at the seam at the top of the orange circle. I used acetone to dissolve it.

The right side pencil mark shows correct alignment for the distance scale and focus barrel. The "+" pencil mark was over the infinity line when the focus barrel separated from the lower part of the helicoid.
I believe it's typical for mirror lenses to be set to focus a bit past infinity.

My only task was to re-grease the helicoid so I didn't disassemble anything below the distance scale.

Good luck, longbo!

**longbo** · 08-24-2021, 03:47 AM

.a.t

Thanks, it worked! I managed to unscrew the barrel. At first, I still couldn't move the focus, but after a bit of heat from my wife's hair dryer, it started to move and is now quite smooth.

Before I reassemble it, what's the best to do with the grease on the helical? Leave it in its current freestate, or clean it off and apply some replacement lubricant?

**.a.t.** · 08-24-2021, 01:11 PM - **1 Like**

Originally posted by longbo

. . .
Before I reassemble it, what's the best to do with the grease on the helical? Leave it in its current freestate, or clean it off and apply some replacement lubricant?

Great! Good to hear you had success.

To prevent a future stuck barrel, I would recommend you clean the lens and apply some fresh grease.

To remove old grease, I use cotton swabs with lighter fuel. My lighter fuel bottle says it's composed of "petroleum distillates". No doubt similar solvents would also work. An old toothbrush can be helpful if the grease is stubborn or hardened.

For new grease, I use Helimax XP:
1oz HELIMAX-XP Camera Telescope Optical Instrument Focusing Helicoid Grease PTFE 36663592361 | eBay

When I was searching for a helicoid grease, Helimax was recommended. It seems to do the job just fine. And I like that it's not too thick / heavy.

**longbo** · 08-24-2021, 07:10 PM

Originally posted by .a.t.

Great! Good to hear you had success.

To prevent a future stuck barrel, I would recommend you clean the lens and apply some fresh grease.

To remove old grease, I use cotton swabs with lighter fuel. My lighter fuel bottle says it's composed of "petroleum distillates". No doubt similar solvents would also work. An old toothbrush can be helpful if the grease is stubborn or hardened.

For new grease, I use Helimax XP:
1oz HELIMAX-XP Camera Telescope Optical Instrument Focusing Helicoid Grease PTFE 36663592361 | eBay

When I was searching for a helicoid grease, Helimax was recommended. It seems to do the job just fine. And I like that it's not too thick / heavy.

Thanks for the info.

08-23-2021, 04:37 AM	#1
longbo Loyal Site Supporter Join Date: Apr 2018 Posts: 98	Tokina 500mm Mirror Lens Focus Locked Staff note: This post may contain affiliate links, which means Pentax Forums may earn a small commission if a visitor clicks through and makes a purchase. If you would like to support the forum directly, you may also make a donation here. I've had a copy of this lens for a while and it was fine last time I used it, but when I got it out to try it on my K3-3, I found that the focus ring was completely seized - not even the slightest movement. The lens has been in a drawer since last used, so it's not been dropped or otherwise abused. Does anyone know what might have happened to it? Any ideas about disassembly to fix it? - I can't see it being worth paying to get it fixed, when similar models are available on eBay for £60 or so. Last edited by longbo; 08-23-2021 at 07:50 AM.

08-23-2021, 10:39 AM	#4
longbo Loyal Site Supporter Join Date: Apr 2018 Posts: 98 Original Poster	Tokina Mirror Lens Focus Seized-up I posted this query in the Dslr Lens Forum, but it struck me that it might be more relevant here, as I'm asking about a problem. If it's not allowed to post in two different fora, my apologies. I've had a copy of the Tokina 500mm Mirror lens for some time, but it's not been used for a while. I got it out to try on my K3-3, but found that the focusing mechanism was locked solid - no movement of the focusing barrel at all. The lens was fine when last used and since then has been in a drawer, so not been dropped or otherwise abused. Can anyone advise what might have happened to it? Does anyone have any disassembly instructions, so I can try a fix?

08-23-2021, 04:34 PM	#8
.a.t. Site Supporter Join Date: Mar 2011 Location: yesterday Photos: Gallery Posts: 1,261	Originally posted by longbo Thanks. I've tried gently warming it with no luck. I'll try a bit more heat and see if that helps. I don't think a professional repair is realistic as eBay has these lenses starting at £60. I'm just hoping someone may know how to get it apart! On my (Sears branded) copy, there are four screws at the upper end of the distance scale which bind it to the focus barrel. When those screws are loosened, the distance scale will drop down and the focus barrel can unscrew from the lower half of the lens. Unless the barrel is stuck! I'm not sure what to recommend other than more heat..? The screws to loosen (orange circle) can be accessed without lifting up the rubber focus grip. But my lens had lacquer on the barrel under the grip. The lacquer was joining the distance scale and focus barrel at the seam at the top of the orange circle. I used acetone to dissolve it. The right side pencil mark shows correct alignment for the distance scale and focus barrel. The "+" pencil mark was over the infinity line when the focus barrel separated from the lower part of the helicoid. I believe it's typical for mirror lenses to be set to focus a bit past infinity. My only task was to re-grease the helicoid so I didn't disassemble anything below the distance scale. Good luck, longbo!

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08-23-2021, 06:22 AM	#2
mlynch53 Forum Member Join Date: Dec 2010 Location: Kentucky Posts: 95	longbo, I also have a Tokina 500mm mirror lens for my Pentax DSLR, and I've never had something like this happen. But to make sure we're talking about the same lens ... On mine, the barrel turns for focus (and it does so very smoothly). You use the term "focus ring" in your original message. Does yours, in fact, have a "ring," or does the barrel turn for focus? Mike

08-23-2021, 07:37 AM	#3
longbo Loyal Site Supporter Join Date: Apr 2018 Posts: 98 Original Poster	Mike, sorry, loose terminology - it's the barrel. Mine too was very smooth - until now!

08-23-2021, 12:31 PM	#5
Bob 256 Site Supporter Join Date: Jun 2008 Location: Idaho Photos: Gallery Posts: 2,375	It might be the lubricant has dried up. One thing you might try is placing the lens in the sun to gently warm it and see if it loosens up (don't let it get scorching hot!). Sometimes you can get it moving that way and redistribute some good lubricant to get it functional. Otherwise it might be a repair job. Could be something got in the helical in which case, the only solution is to disassemble the lens - sorry can't help you there.

08-23-2021, 02:13 PM	#6
longbo Loyal Site Supporter Join Date: Apr 2018 Posts: 98 Original Poster	Originally posted by Bob 256 It might be the lubricant has dried up. One thing you might try is placing the lens in the sun to gently warm it and see if it loosens up (don't let it get scorching hot!). Sometimes you can get it moving that way and redistribute some good lubricant to get it functional. Otherwise it might be a repair job. Could be something got in the helical in which case, the only solution is to disassemble the lens - sorry can't help you there. Thanks. I've tried gently warming it with no luck. I'll try a bit more heat and see if that helps. I don't think a professional repair is realistic as eBay has these lenses starting at £60. I'm just hoping someone may know how to get it apart!

08-23-2021, 03:24 PM	#7
Not a Number Moderator Join Date: Mar 2012 Location: Venice, CA Posts: 10,526	Duplicate threads are discouraged by the Forum Rules and Guidelines. Questions like these on a specific lens are a toss-up between the lens discussion or trouble shooting forums. Pick one and stick with it in the future. The moderating staff may decide one or the other forums is better than the other and move the threads. Redundant threads are either closed, deleted or merged.

08-24-2021, 03:47 AM	#9
longbo Loyal Site Supporter Join Date: Apr 2018 Posts: 98 Original Poster	.a.t Thanks, it worked! I managed to unscrew the barrel. At first, I still couldn't move the focus, but after a bit of heat from my wife's hair dryer, it started to move and is now quite smooth. Before I reassemble it, what's the best to do with the grease on the helical? Leave it in its current freestate, or clean it off and apply some replacement lubricant?

08-24-2021, 01:11 PM - 1 Like	#10
.a.t. Site Supporter Join Date: Mar 2011 Location: yesterday Photos: Gallery Posts: 1,261	Originally posted by longbo . . . Before I reassemble it, what's the best to do with the grease on the helical? Leave it in its current freestate, or clean it off and apply some replacement lubricant? Great! Good to hear you had success. To prevent a future stuck barrel, I would recommend you clean the lens and apply some fresh grease. To remove old grease, I use cotton swabs with lighter fuel. My lighter fuel bottle says it's composed of "petroleum distillates". No doubt similar solvents would also work. An old toothbrush can be helpful if the grease is stubborn or hardened. For new grease, I use Helimax XP: 1oz HELIMAX-XP Camera Telescope Optical Instrument Focusing Helicoid Grease PTFE 36663592361 \| eBay When I was searching for a helicoid grease, Helimax was recommended. It seems to do the job just fine. And I like that it's not too thick / heavy.

08-24-2021, 07:10 PM	#11
longbo Loyal Site Supporter Join Date: Apr 2018 Posts: 98 Original Poster	Originally posted by .a.t. Great! Good to hear you had success. To prevent a future stuck barrel, I would recommend you clean the lens and apply some fresh grease. To remove old grease, I use cotton swabs with lighter fuel. My lighter fuel bottle says it's composed of "petroleum distillates". No doubt similar solvents would also work. An old toothbrush can be helpful if the grease is stubborn or hardened. For new grease, I use Helimax XP: 1oz HELIMAX-XP Camera Telescope Optical Instrument Focusing Helicoid Grease PTFE 36663592361 \| eBay When I was searching for a helicoid grease, Helimax was recommended. It seems to do the job just fine. And I like that it's not too thick / heavy. Thanks for the info.