Repair filter threads on lens?

I recently acquired a used Vivitar lens [ 28-90mm w/ 62mm filter threads ]
that has been damaged in one spot. It appears to have been hit on the front
edge and has left the lens housing at that point slightly " out of round "
and unable to accept the filter. What is the process to repair this problem?
Thanx

I can't imagine how to repair such a fine thread. If this were a standard
mechanical thread instead of an extremely fine pitch large diameter thread,
I would carefully set it up on a lathe and use the post to carefully feed a
thread tap in by hand. But filter threads are very delicate (don't you know
that now for sure?), and not a pitch or diameter which I have ever seen.
The fact that it is likely anodized aluminum doesn't help either. Seems like
a nearly impossible task. I will follow this with interest to see if
someone has a miracle cure.

Good luck,

PSsquare


"lib" wrote in message
...
I recently acquired a used Vivitar lens [ 28-90mm w/ 62mm filter threads ]
that has been damaged in one spot. It appears to have been hit on the
front
edge and has left the lens housing at that point slightly " out of round "
and unable to accept the filter. What is the process to repair this
problem?
Thanx

"lib" wrote in message
...
I recently acquired a used Vivitar lens [ 28-90mm w/ 62mm filter threads ]
that has been damaged in one spot. It appears to have been hit on the
front
edge and has left the lens housing at that point slightly " out of round "
and unable to accept the filter. What is the process to repair this
problem?
Thanx


If the threads have not been crushed, you can use a piece of hardwood or
plastic that you have rounded on one end and a small hammer to tap out the
ding.

"lib" schrieb im Newsbeitrag
...
I recently acquired a used Vivitar lens [ 28-90mm w/ 62mm filter threads ]
that has been damaged in one spot. It appears to have been hit on the
front
edge and has left the lens housing at that point slightly " out of round "
and unable to accept the filter. What is the process to repair this
problem?

You can buy a special tool from www.micro-tools.com (or www.micro-tools.de
for europe) to "round" the front. (e.g.
http://www.micro-tools.com/Merchant2...uct_Cod e=LRP
or
http://www.micro-tools.com/Merchant2...uct_Cod e=LV1
or
http://www.micro-tools.com/Merchant2...duct_Cod e=LR)

Or give the lens to a foto repair.

Peter

On Fri, 13 Feb 2004 14:23:08 UTC, "lib" wrote:

I recently acquired a used Vivitar lens [ 28-90mm w/ 62mm filter threads ]

....which seemingly is not a lens for medium-format cameras, so this is OT
here, but, well....

that has been damaged in one spot. It appears to have been hit on the front
edge and has left the lens housing at that point slightly " out of round "
and unable to accept the filter. What is the process to repair this problem?

Before you start, check if the general alignment of the tubes seems to be
o.k.; on zoom lenses, misalignment will not make you happy, and you might
be better off if you returned the lens. If you're satisfied with the
overall state (maybe even check by doing a test film), then you could try
to repair the front tube.

Here goes.

.... if you have the guts and the lens isn't worth a lot (which I suppose to
be true ;-)), then you can take some layers of strong cloth, or thin,
elastic plywood (or even cardboard) strips and a pair of pliers, cover the
thread with the cloth or the plywood and sensibly ease the thread into the
right way with the pliers. Take a matching filter to check if you corrected
the dent sufficiently.

Disclaimer: don't blame it on me or anyone else if this fails and the
pliers damage the actual thread inside the tube. But I've done this several
times, not caring about how this would look afterwards as long as would
work, and it did.

Hartmut
--
Please use 'Reply-to' for personal e-mail.
Bitte fuer direkte emails 'Reply-to' benutzen.

On Fri, 13 Feb 2004 14:23:08 GMT, "lib" wrote:

I recently acquired a used Vivitar lens [ 28-90mm w/ 62mm filter threads ]
that has been damaged in one spot. It appears to have been hit on the front
edge and has left the lens housing at that point slightly " out of round "
and unable to accept the filter. What is the process to repair this problem?
Thanx

If the edge damage isn't excessive, camera shops have special tools
intended for this purpose. If the edge is pushed over too far, you
may have to order a replacement filter ring (I had to do this for a
Nikkor lens last year), cost about $30.

"lib" wrote in message ...
I recently acquired a used Vivitar lens [ 28-90mm w/ 62mm filter threads ]
that has been damaged in one spot. It appears to have been hit on the front
edge and has left the lens housing at that point slightly " out of round "
and unable to accept the filter. What is the process to repair this problem?

First, you will have to de-bulge the filter thread roughly so that it
has a round shape again. A suitable method is described in the repair
article section of www.kyphoto.com/classics. Micro-Tools and a guy in
Germany sell tools to do this in a more precise way.

However, in most cases the thread will have round shape again, but the
thread itself will be more or less ruined and you still won't be able
to attach a filter.

DO NOT try to screw in a filter with force to re-shape the thread.
Most filter mounts are made of aluminium, just like the lens filter
threads, and aluminium threads get stuck very easily (that's why
manufacturers like B+W use brass filter mounts).

Mechanists have a special tool for manually re-shaping threads, it is
called 'thread chaser'. I have access to such a tool but could not
find any source to buy it yet. Filter threads are metric and have
0.75mm pitch in most cases (0.5mm below roughly 40mm diameter), so it
will be even more difficult to locate a tool for this pitch in US and
U.K. Basically it is a handle with a blade bent 90 deg. and wearing a
couple of 'teeth' in proper pitch and triangular shape, and you will
have to 'scratch' the remaining thread until it is in proper shape
again. I have successfully repaired several filter threads on
fixed-lens cameras like this.

Winfried

"KBob" wrote in message
...
On Fri, 13 Feb 2004 14:23:08 GMT, "lib" wrote:

I recently acquired a used Vivitar lens [ 28-90mm w/ 62mm filter
threads ]
that has been damaged in one spot. It appears to have been hit on the
front
edge and has left the lens housing at that point slightly " out of round
"
and unable to accept the filter. What is the process to repair this
problem?
Thanx

If the edge damage isn't excessive, camera shops have special tools
intended for this purpose. If the edge is pushed over too far, you
may have to order a replacement filter ring (I had to do this for a
Nikkor lens last year), cost about $30.

The professional tools for this job are priced on the dark side of the moon.
They used to be reasonable, but they are easily 300% overpriced today. A
trip to the camera shop might be in order. If you are brave, you can try
tapping the dent out. Use a wooden piece (a 3/8" dowel is good, plastic
works, too.) and place it on the edge of the dent and tap it outwards. You
don't even have to _see_ the movement of the ring. It moves. Go slow. And
then do the same the opposite edge, then the other again, working back and
forth in slowly toward the center. It is unlikely you will have to tap all
the way into the center before the filter goes on.

But that's far easier said than done. Go slow. Or go faster to a
professional repair shop where they have the $250 tool that should cost $20.

You may want to try MSC

http://www.mscdirect.com/

They have an online catalog and (if you ask them) catalog on CD. Prices
are high but not unreasonable, shipping is excellent. They have a low
price sister company called ENCO -sometimes the same items are featured
in both places. You'll have to look.

Regards,

Marv

Winfried Buechsenschuetz wrote:

SNIP

Mechanists have a special tool for manually re-shaping threads, it is
called 'thread chaser'. I have access to such a tool but could not
find any source to buy it yet. Filter threads are metric and have
0.75mm pitch in most cases (0.5mm below roughly 40mm diameter),



Winfried

In article , Winfried
Buechsenschuetz writes
"lib" wrote in message
...
I recently acquired a used Vivitar lens [ 28-90mm w/ 62mm filter threads ]
that has been damaged in one spot. It appears to have been hit on the front
edge and has left the lens housing at that point slightly " out of round "
and unable to accept the filter. What is the process to repair this problem?

First, you will have to de-bulge the filter thread roughly so that it
has a round shape again. A suitable method is described in the repair
article section of www.kyphoto.com/classics. Micro-Tools and a guy in
Germany sell tools to do this in a more precise way.

However, in most cases the thread will have round shape again, but the
thread itself will be more or less ruined and you still won't be able
to attach a filter.

DO NOT try to screw in a filter with force to re-shape the thread.
Most filter mounts are made of aluminium, just like the lens filter
threads, and aluminium threads get stuck very easily (that's why
manufacturers like B+W use brass filter mounts).

Mechanists have a special tool for manually re-shaping threads, it is
called 'thread chaser'. I have access to such a tool but could not
find any source to buy it yet. Filter threads are metric and have
0.75mm pitch in most cases (0.5mm below roughly 40mm diameter),

I believe camera lens filter threads are all 0.75mm pitch; certainly the
27mm filter thread on my Coolpix is - I cut a thread on a microscope
eyepiece last year to fit on it.

so it
will be even more difficult to locate a tool for this pitch in US and
U.K.

Industry in the UK is almost entirely metric. It is true that a lot of
old imperial tooling is available very cheaply on the surplus market
(much to the advantage of model engineers, who tend to be, ahem, more
mature, and wedded to the old system). The metric stuff is readily
available new from tooling suppliers, and can often be found on surplus
stands at exhibitions. I must admit I have never looked for a 0.75mm
chaser though - might be a good ides to do so!

Interestingly, hobbyists often buy chasers to grind into lathe tools,
which seems a shame, but not many people have a need for them as
chasers.

I agree the USA is still mostly in the dark ages. The chemical engineers
there still use the Fahrenheit/Rankine temperature scale, for goodness
sake!

Basically it is a handle with a blade bent 90 deg. and wearing a
couple of 'teeth' in proper pitch and triangular shape, and you will
have to 'scratch' the remaining thread until it is in proper shape
again. I have successfully repaired several filter threads on
fixed-lens cameras like this.

Winfried

--
David Littlewood