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01-02-2008, 05:21 PM   #1
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Damaged rear lens element on F70-210, can the element be replaced?

I bumped the rear element on my SMC F 70-210 into the corner edge of our granite counter top. You may ask how could one be so careless?

My idiot husband decided to sneak up behind me and tickle my sides. I flinched with lens in hand and perfectly dinged the glass. When he comes out of hiding at his best buds house, he is going to have ding in his @$$. (Hmm, where did I put those spiked heels )

Is there a way to replace the glass? I have an 70-210 that I picked up on the real cheap with fungus on the front elements, thought I might need it for one day for parts. That day is here.

In my search for ideas on repair, I found two links of interest,

Pentax 70-210 Repair

Brian Ayling's photographic repair tips

I pray not having to use the later link.

Any help or thoughts would greatly be appreciated.

Wendy


Last edited by WendyB; 01-02-2008 at 05:27 PM.
01-02-2008, 05:56 PM   #2
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If you have 2 identical lenses, you can simply use a lens wrench to unscrew the last metal retaining ring (usually super tight when new) that holds the last element/glass. It is not a complicated job, BUT, you will need a rigid wrench with good fit for the job. The best way to do it is with a piece of very thin dental rubber sits between the lens and the wrench to prevent scratch because one slip and you will most certain damage something. With the proper skill and tool, it should be a 15mins job.
01-03-2008, 07:33 AM   #3
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QuoteOriginally posted by wlachan Quote
If you have 2 identical lenses, you can simply use a lens wrench to unscrew the last metal retaining ring (usually super tight when new) that holds the last element/glass. It is not a complicated job, BUT, you will need a rigid wrench with good fit for the job. The best way to do it is with a piece of very thin dental rubber sits between the lens and the wrench to prevent scratch because one slip and you will most certain damage something. With the proper skill and tool, it should be a 15mins job.
Thank you for the help,

Just bought a spanner wrench for this on the bay. might as well use the right tool for the procedure.

Does anyone know if the thread is left or right handed? I just see myself turning it the wrong way and creating more of a problem.

I will take photo's of the operation on the lens, I wish I could figure out why I can not get by my firewall to post any images.

Thanks again for your help Alan and I just adore your images at Pbase,

Sincerely,

Wendy
01-03-2008, 08:58 AM   #4
roy
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wendy,
being a F lens, pentaxUSA may still stock it or have it available. call 1-800-877-0155, ext 2005, and ask for Lynn in parts.. have your info ready and be polite. she's always very busy

01-03-2008, 09:04 AM   #5
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Hi Wendy.

I took apart an old Pentacon 50mm a little while ago and the thread was lefty-loosey. I'm guessing it would be the same but can't say for sure. There should be enough of the thread showing to tell which direction to go.

Which spanner did you get? I need to get one myself.

Slick
01-03-2008, 11:51 AM   #6
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QuoteOriginally posted by Slick Quote
Hi Wendy.

I took apart an old Pentacon 50mm a little while ago and the thread was lefty-loosey. I'm guessing it would be the same but can't say for sure. There should be enough of the thread showing to tell which direction to go.

Which spanner did you get? I need to get one myself.

Slick
Hi Slick,

Thank you for your help,

I picked up the 1/32 version of this set, $15.98 +4.50 shipping, they have a 3/32 version but for my need I felt the 1/32 would narrow enough so as to not scratch the lens. My dentist is giving me a small piece of dental rubber also.
*New* 3 Spanner Wrench Set 1/32" 3/32" 3/16" Tool - eBay (item 140141682678 end time Jan-20-08 20:48:13 PST)

Sincerely,

Wendy
01-03-2008, 12:03 PM   #7
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QuoteOriginally posted by roy Quote
wendy,
being a F lens, pentaxUSA may still stock it or have it available. call 1-800-877-0155, ext 2005, and ask for Lynn in parts.. have your info ready and be polite. she's always very busy
Hi Roy,

Thank you very much for the suggestion, I will give her a call. I hope they still have the element in stock. Now that a spanner wrench is on its way I might just attempt to tackle the minor fungus problem on the front and second element of the F70-210 I picked up for 50 cents at a flea market. I have been keeping that lens far away from my equipment.

Ps; I am am always polite but not so much with my hub's the last few days

Sincerely,

Wendy
01-03-2008, 12:58 PM   #8
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QuoteOriginally posted by WendyB Quote
Does anyone know if the thread is left or right handed? I just see myself turning it the wrong way and creating more of a problem.
Wendy

Except for some special parts like rewind shafts and winding arms on old cameras, almost everything else are unscrewed like regular screws (not sure called left or right handed), that include the retaining rings on lenses. But keep in mind that some glasses are grouped as a single assembly and it is usualy a good idea not to disassemble it. Just disassemble as little as you can to get the job done. For removing fungus, you can use 70% isopropyl alcohol (30% water) first, then pure isopropyl to remove the smear as the last step. Good luck! It will be fun.

01-03-2008, 02:48 PM   #9
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Hey Wendy,
If at all possible try not to take the mount apart- I have a f 28-80mm that I adjusted the aperture on and it was a real bear to get the contacts and little springs all back in place. I put tape on the flange to keep the contacts from falling out and put the springs into place with a slightly magnetized screwdriver and a toothpick. there is a spring and tiny detent ball under the aperture ring too. Gave me an appreciation for camera repair techs.
01-03-2008, 05:14 PM   #10
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Oops, not now dear.... dammit!!

QuoteOriginally posted by WendyB Quote
I bumped the rear element on my SMC F 70-210 into the corner edge of our granite counter top. You may ask how could one be so careless?

My idiot husband decided to sneak up behind me and tickle my sides. I flinched with lens in hand and perfectly dinged the glass. When he comes out of hiding at his best buds house, he is going to have ding in his @$$. (Hmm, where did I put those spiked heels )


Wendy
Hmmmm is right, moral of the story is, never sneak around the kitchen in spiked heels and...... A Pentax Lens??



Hope you can fix it Wendy

Phil
01-04-2008, 06:14 PM   #11
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QuoteOriginally posted by borno Quote
Hey Wendy,
If at all possible try not to take the mount apart- I have a f 28-80mm that I adjusted the aperture on and it was a real bear to get the contacts and little springs all back in place. I put tape on the flange to keep the contacts from falling out and put the springs into place with a slightly magnetized screwdriver and a toothpick. there is a spring and tiny detent ball under the aperture ring too. Gave me an appreciation for camera repair techs.
Thanks for the advice, the fungus is only on the front two elements and not too bad. Just waiting for the spanner to arrive
01-04-2008, 08:51 PM   #12
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May I suggest you get a repair shop to get it done. It is easy enough to open up a lens but on reassembly, the lens would need to be collimated to ensure proper focus at infinity.
01-04-2008, 08:57 PM   #13
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QuoteOriginally posted by creampuff Quote
May I suggest you get a repair shop to get it done. It is easy enough to open up a lens but on reassembly, the lens would need to be collimated to ensure proper focus at infinity.
Not in this case.
01-05-2008, 08:41 AM   #14
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Adjusting infinity focus on Pentax lenses

QuoteOriginally posted by creampuff Quote
May I suggest you get a repair shop to get it done. It is easy enough to open up a lens but on reassembly, the lens would need to be collimated to ensure proper focus at infinity.
I had a problem with my 50mm F2 SMC-A lens not focusing to infinity. If you remove the outer ring with the text on it (using a rubber stopper to grip it) there are three screws down in the lens past the lens group. Focus the lens to infinity, loosen these screws and the focusing ring is decoupled from the lens. Back off the lens focusing ring from a little from infinity, tighten one screw, focus to infinity and then loosen the screw. Move the focusing ring back to the infinity stop and retighten all three screws. Voila! the lens now focuses to infinity. The way to focus to infinity is to mount the lens on your camera body,focus the lens at some distant object (at least 50 meters away) and make sure it is in clear focus. No optical bench is necessary.

With Pentax zooms, the procedure is even easier. The rubber over the focusing ring needs to be removed. Just get a smooth flat object between the focusing ring and the rubber cover and pry it away from the adhesive, then remove the rubber. It is a one piece cylindrical piece of rubber. You will find three screws on the end of the focusing barrel that is nearest the lens mount. Loosen these and follow the procedure for the 50mm lens above for adjusting infinity focus.

This procedure is actually a lot easier to do than to describe!
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