Another lens problem

So I found a supposedly rare and exceptional Vivitar Series 1 28-90mm f2.8-3.5 in Pentax A mount. I was shopping for a lens in that range and this one was in mint condition at a great price so I picked it up. I tried it out on a Pentax digital body and found that it was overexposing. I put it on one of my Super Programs and opened the film back so I could watch the aperture and sure enough, it is closing almost imperceptibly more slowly than it should. I mean, you really have to be paying attention and watch several times to really be convinced that the lens has a problem.

I sent an email off to Vivitar and they replied very quickly that this lens was made before the company was bought out by another so they conveniently washed their hands of the problem, ststing that they would not attempt a repair.

I figure that I'm not into it for that much and a repair may exceed the value of the lens so I might just attempt it myself. Has anybody here ever disassembled this lens? I've spent some time poking around for a tutorial with no success. Can anyone point me to an online tutorial or video of this lens being torn down or reassembled?

What you describe sounds like a normal aging issue. Any competent repair shop should be able to restore functionality. If it's really supposedly rare it should be worth a few dollar investment rather than risking its eternal damnation.

ctrout said:

I figure that I'm not into it for that much and a repair may exceed the value of the lens so I might just attempt it myself. Has anybody here ever disassembled this lens? I've spent some time poking around for a tutorial with no success. Can anyone point me to an online tutorial or video of this lens being torn down or reassembled?

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The value of the lens is irrelevant -- the question is, is this a lens you want to use, will use, even need to use?

If so, spend the bux to get it fixed right. I doubt it will be much more than $100, and that's not much for a prime piece of gear.

Please provide a picture of the camera mount end of your lens.
How good are your mechanical skills?

ctrout said:

I figure that I'm not into it for that much and a repair may exceed the value of the lens so I might just attempt it myself.

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If it is not an expensive lens and you can cope with failure then have a go yourself. Looking at a photo of the lens it looks fairly easy to get near the shutter leaves. The smallest drop of lighter fluid on the end of a needle will spread like wild fire on the leafs. So don't splash it around or flick the aperture arm quickly. Just move it slowly and keep the lens on its side till it does. Let it dry then the leafs should work freely. The lighter fluid un-glugs the old oil. Too much lighter fluid will remove the oil and the leafs will go dry so use the smallest drop you can. I have fixed a few like this and they are still working fine. Good luck.

Aperture blades should be dry, no oil. The aperture mechanism should be dry, no grease.
Lighter fluid is the worst degreaser one can use on a camera.
Naphtha, lighter fluids main ingredient is used in contact cleaners but the lighter fluid mix is a -10 in camera repair.

I looked at the web pictures, I want to see Ctrout's.

shutterfinger said:

Aperture blades should be dry, no oil. The aperture mechanism should be dry, no grease.
Lighter fluid is the worst degreaser one can use on a camera.
Naphtha, lighter fluids main ingredient is used in contact cleaners but the lighter fluid mix is a -10 in camera repair.

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Uh Oh! I stuffed up there. Should have joined APUG earlier. "Every day is for learning". Look forward to the correct solution.
Robin.

We may have to agree to disagree on the use of lighter fluid. About 10 years ago one drop of it on a Q tip cleared up a sticky GIII shutter and it's been working fine ever since.

I don't know if I would use it on aperture blades, however.

My very old Betax shutter was sticking pretty bad - dismantled somewhat and washed moving parts in Ronson Lighter fluid - left dismantled to dry - that was months ago and it is working flawlessly since...?

ransel said:

My very old Betax shutter was sticking pretty bad - dismantled somewhat and washed moving parts in Ronson Lighter fluid - left dismantled to dry - that was months ago and it is working flawlessly since...?

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There are many of us who have had similar experience. Washing with lighter fluid and drying works for some shutters yet others, like SynchroCompur, really want their lubrication too. I've heard of folks doing similar with SLR lenses to free up sluggish aperture blades. But I'm not daring enough to do that with any of mine.

i have a little shutter, can't remember the name of it, it was harvested off of a folder
it was sticky so i flused it out with lighter fluid, ronsionl or whatever it is called ... and
it works EVEN WORSE than it did before. lighter fluid isn't the answer to every sticky shutter,
some maybe, yes, others, no,

My experience with distilled spirits ( Ronsonal , etc ) has been a god send all but once and that was
with an Iskra 1 . That it dissolves oil and grease doesn't mean those contaminants evaporate with the fluid.
Inadequate flushing , just leaves the old oil or grease someplace else . If it's of low value and you have
little to loose , then go ahead . It's your adult choice . Peter

Naphtha the main ingredient in lighter fluid will dissolve plastics and rubber used in shutters. The turn of the century shutters to the early 1930's I assume were all metal so any degreaser that was not acid was usable.
Ilex shutters use hard rubber shutter blades, other makes use rubber bumpers inside the case (Wollensak) and plastics are in most flash sockets.
Naphtha diluted 50% to 60% with alcohol makes a good cleaner that will not damage parts and dries quickly.
Lacquer thinner is a very good cleaner but it will remove the bluing off the shutter and aperture blades and strip the finish off the case.
90% Isopropyl Alcohol is a very good cleaner and costs about the same as lighter fluid. It is not as flammable as lighter fluid but will cause paint to peel off if used in an ultrasonic cleaner and run 3 or more connective 5 minute cycles which gets it hot enough to burn. I will continue to throw a lit match to lighter fluid every time I read it recommended for shutter/camera cleaning.

Robin, the aperture lever operated by the camera and its return spring may use grease from the factory. Its a trace amount and one will not see it and its only where the operating ring touches or rides against the lens barrel.

Ctrout, from pictures on the web you may need to remove the rear element to prevent accidental damage, this will depend on the camera mount system. The screws that hold the mount ring to the lens barrel may be set with a thread locker that has to be dissolved to remove the screws, finger nail polish remover should work for this. Extra fine powdered graphite can be used on the aperture blades to improve their operation.
When removing internal lens cells their exact position must be maintained on reassembly. Some lens use stop ridges inside the lens others use stop rings that must be unscrewed before the next lens element can be removed. Count and record the number of turns. The outermost elements may have shims under them, they must be reinstalled on reassembly.

shutterfinger said:

Naphtha the main ingredient in lighter fluid will dissolve plastics and rubber used in shutters. The turn of the century shutters to the early 1930's I assume were all metal so any degreaser that was not acid was usable.
Ilex shutters use hard rubber shutter blades, other makes use rubber bumpers inside the case (Wollensak) and plastics are in most flash sockets.
Naphtha diluted 50% to 60% with alcohol makes a good cleaner that will not damage parts and dries quickly.
Lacquer thinner is a very good cleaner but it will remove the bluing off the shutter and aperture blades and strip the finish off the case.
90% Isopropyl Alcohol is a very good cleaner and costs about the same as lighter fluid. It is not as flammable as lighter fluid but will cause paint to peel off if used in an ultrasonic cleaner and run 3 or more connective 5 minute cycles which gets it hot enough to burn. I will continue to throw a lit match to lighter fluid every time I read it recommended for shutter/camera cleaning.

(snip).

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These are excellent things to call to everyone's attention... with the exception of your lit match.

One additional reminder - Isopropyl Alcohol is also part water. So dry quickly and thoroughly to avoid rusting.

I won't have to worry about all of the warnings about damage to shutter parts since the shutters in every single K mount camera ever made are in the camera body and not in the lens. I'll keep it in mind though if I ever go inside of one of my Mamiya RB67 lenses.

BrianShaw said:

Isopropyl Alcohol is also part water. So dry quickly and thoroughly to avoid rusting.

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90$ Alcohol has 10% water. I take shutters out of the ultrasonic cleaner with 90% alcohol and let it sit on the bench for a few hours to a day or two depending on my schedule and never have rust start to form. If shutter or aperture blades were on the verge or rusting before the alcohol bath then they are still prone afterwards.
Soak rusted parts in cider vinegar for 15 to 30 minutes, rinse with cool water, dry, apply oil, graphite or similar dry lubricant, metal bluing to prevent rust forming again. Parts with rust removed in cider vinegar will start rusting again within 30 minutes if not treated promptly.

ctrout said:

I won't have to worry about all of the warnings about damage to shutter parts since the shutters in every single K mount camera ever made are in the camera body and not in the lens. I'll keep it in mind though if I ever go inside of one of my Mamiya RB67 lenses.

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Will we (I) ever see a picture of the rear of your lens or do you feel competent to tackle it?

As I have read elsewhere and based on the parts diagram of the lens, it appears that the diaphragm is located behind the second element and is accessed through the front of the lens. As soon as I get my hands on a proper spanner, I'll probably just tackle it myself. If I'm going to be involved in this hobby, I should probably eventually start learning how to do some of the more common maintenance tasks. I mean, if I was able to keep F-4s, F-16s, A-10s, and F-15Es flying for 21 years, I don't see why I couldn't take a crack at this mechanical device.

ctrout said:

I mean, if I was able to keep F-4s, F-16s, A-10s, and F-15Es flying for 21 years, I don't see why I couldn't take a crack at this mechanical device.

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Definitely have a go. I got a free Tamron zoom 70-210 that was growing mushrooms inside. It took me 2 days of occasionally studying it to work out how they put it together. Eventually realised it was a bit like a rubics cube. The centre cylinder has a couple of black screws. Take them out then the tube spins to reveal more screws. Once all removed the zoom just pulls apart into two sections. All the elements and diaphragm are then accessible. That lens is like new again now and takes nice shots (for a basic Tamron).
Robin.

ctrout said:

I mean, if I was able to keep F-4s, F-16s, A-10s, and F-15Es flying for 21 years, I don't see why I couldn't take a crack at this mechanical device.

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I was one of the best on troubleshooting guidance and flight control systems on the AGM28B Hound Dog missile that launched from a B52. The upgraded version of that guidance system was used in Boeing 747 aircraft. My mechanical abilities intimated some coworkers and complimented many others.

This style spanner http://www.ebay.com/itm/FOME-Spanne...182755?hash=item3adc1fec23:g:wwAAAOSwol5YveDU is very good for lens/camera work.
They show up for less money on occasion.

That is the spanner that I'm looking at. I found it on Amazon for about the same price.

The SKGrimes round tip spanner is a good complimentary spanner for repair work.
http://www.skgrimes.com/products/spanner-wrench
It is most helpful in disassembling lens.

I have a couple of the Vivitar S1 28-90 lenses, one of which I dismantled. I took it apart a few years ago and now I'm a bit hazy as to why I did. Probably stuck aperture blades. Whenever I encounter this condition, I always begin by approaching the iris from the rear. Many times, this is the way to go. For example, with the Vivitar S1 24-48mm, the aperture blades can easily be accessed when approached from the rear. I guess I must have run into a problem with the 28-90 though, because I ended up totally dismantling the lens. It's still in pieces and the reason why is because of the small screws that thread into the barrel which have nylon-looking bushings. These screws with bushings ride in channels in another collar, which controls the way the element groups zoom in and out. A weak link about this lens is these screws easily strip out of the barrel they're threaded into, and when this happens, you have two choices -- find a way to cement the screws into place or junk the lens. I did the latter because in the process of discovering how the lens operated, I managed to shred a couple of the nylon bushings. Everything about this lens is fragile on the interior, so if you're really gonna dismantle it, treat it as if it is made from egg shells.

I also have the replacement to this lens, the S1 28-105, and I have a couple of them, one of which I dismantled, but the reason why I dismantled it was because the zoom stopped working the way it was supposed to. Here's what happened. When I first got the lens (off eBay or shopgoodwill, one of the two), the zoom operation was very stiff, so I figured if I just push-pulled on it several times that might help loosen things up. Well, I guess I push-pulled too aggressively because when I took it apart, a few of the screws with bushings had become stripped out of the barrel. So that lens got added to the junk pile, too. So, a word to the wise: if the zoom operation is stiff, don't over-work it. Easy does it and all that until you've had the lens properly serviced.

I've been using naphtha for years as a general solvent, but I've always kept in mind this simple truth -- the solvent may loosen up gummed up stuff, but that stuff is still there after the solvent evaporates. So that stuff has to be cleaned away completely. The solvent helps in the cleaning process. I usually use Q-tips and blunted toothpicks for this. Then when the item is cleaned, the gummed up stuff can be replaced with the proper lubricant. I usually use a drop or two of light machine oil, but of course I leave the iris blades completely dry. Sometimes I'll use alcohol or acetone (fingernail polish remover) as the solvent, but I always have to clean up the residual water that's left behind when I use alcohol, and I have to be careful of how I use acetone, since it can melt certain types of plastic and strip some types of paint. Naphtha is just more benign and practical -- to me.