[zeebanker]

Gentlemen,
For your viewing pleasure (and my continuing edjumacation) I present two more Craigslist lenses:

Exhibit A: Cosinon 200mm F4. This one is missing a diaphragm. I shook it, looked at the front, back, shined a flash light into it. No F-stop. Nada. Can an aftermarket diaphragm be installed? It seems to take decent pictures and is otherwise ok (manual of course). Can it be repaired or should I only use it as a wide open lens and play with exposure time and ISO when taking pictures?

Exhibit B: Vivitar 35mm Wide Angle F2.8. This one was given to me for free by its previous Craigslist owner. Several questions:
a. Can the diaphragm be repaired? Can I "gently" push on it to see if it pops in? Or should it be replaced? Can it be replaced?
b. What type of mount is it? It appears to be a screw type and appears to have two different "mounts": an outside ring of about 30mm diameter and once that's removed, an inside ring of about 20mm diameter. I'm pretty sure an adapter exists, just don't know what its called.
c. Should I even bother trying to fix this?
d. If not salvageable as a lens, what potential uses could its parts have?

As always, your thoughts/input much appreciated.

PS: I now believe that I got carried away when I bought this box of lenses from said Craigslist vendor and overpaid. Lesson learned.

Oh, and my body is a K5-iiS

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Last edited by zeebanker; 09-12-2020 at 08:03 PM.

[pepperberry farm]

I'll step in and give an opinion:

you wasted your money... unless there were other lenses in that mystery box, these two will make for pretty bokeh/background noise for other shots....

the Vivitar may be fun to play with to see if you can put it back together, but beyond that..... nope...

[c.a.m]

Hi @zeebanker,

Your useful pictures and annotations provide a clear illustration of the problems. I'm afraid that neither lens is functional nor repairable.

Assuming that you can mount the Cosina on your camera, you could possibly use it fully open at f/4. I'd suggest that you take care when mounting it, in case the mount has been damaged. There are a couple of user reviews here: Cosina MC Cosinon T 200mm F/4 Lens Reviews - Cosina Lenses - Pentax Lens Review Database

I'm not sure about the mount on the Vivitar. A bent blade means the diaphragm is kaput.

- Craig

[Just1MoreDave]

The Vivitar might be repairable with some work. One possibility: just remove the broken blade. Maybe the aperture is round enough. Blades are so thin, creases are difficult or impossible to remove. Sometimes the guide pins have sheared off. Techniques for repairing sheet metal are hard to scale down to that size.

You'd think that a clever third party lens maker would standardize the aperture mechanism and make the same thing for several lenses. But it seems like every lens is a collection of custom parts for just that lens. So you probably won't find an aperture for the 200mm, even if it was carefully removed for some excellent reason.

[zeebanker]

I'll step in and give an opinion:

you wasted your money... unless there were other lenses in that mystery box, these two will make for pretty bokeh/background noise for other shots....

the Vivitar may be fun to play with to see if you can put it back together, but beyond that..... nope...

Because you asked...

Also included in the mystery box in addition to the two beauties above are:

Three lenses:
1. 135mm F2.8 prime lens. Says "PK" on it near the mount. Don't know what that means. Has some oil on the diaphragm blades. Seems to work ok. Not sure if its an auto.
2. Albinar 28mm F2.8 Macro. Seems to work fine.
3. SMC Pentax M f50mm F1.4. Works fine.

Bonus material:
1. Pentax MV1 body
2. Two vintage lens cases, smell old and moldy, but look cool.
3. A Vivitar flash (untested, not pictured)


What do you think? Happy to ship the MV1 body to anyone who might want it for cost of shipping. Or should I donate it to the forum?

---------- Post added 08-11-20 at 07:13 PM ----------

The Vivitar might be repairable with some work. One possibility: just remove the broken blade. Maybe the aperture is round enough. Blades are so thin, creases are difficult or impossible to remove. Sometimes the guide pins have sheared off. Techniques for repairing sheet metal are hard to scale down to that size.

You'd think that a clever third party lens maker would standardize the aperture mechanism and make the same thing for several lenses. But it seems like every lens is a collection of custom parts for just that lens. So you probably won't find an aperture for the 200mm, even if it was carefully removed for some excellent reason.

One possibility: just remove the broken blade. Maybe the aperture is round enough.

Great idea. I'll give it a try. The thing expands and contracts fine, just that when partially open, there's that extra gap in the blades through which light enters. Could cause some vignetting but can't hurt trying. I'll still need a mount adapter though.

[pepperberry farm]

Because you asked...

Also included in the mystery box in addition to the two beauties above are:

Three lenses:
1. 135mm F2.8 prime lens. Says "PK" on it near the mount. Don't know what that means. Has some oil on the diaphragm blades. Seems to work ok. Not sure if its an auto.
2. Albinar 28mm F2.8 Macro. Seems to work fine.
3. SMC Pentax M f50mm F1.4. Works fine.

Bonus material:
1. Pentax MV1 body
2. Two vintage lens cases, smell old and moldy, but look cool.
3. A Vivitar flash (untested, not pictured)


What do you think? Happy to ship the MV1 body to anyone who might want it for cost of shipping. Or should I donate it to the forum?

"PK" means it is a Pentax K-mount lens - cool mystery box of lenses....

[LensBeginner]

The only thing of interest (to me... not sure about the value of the body) is the 50/1.4, which is not a bad lens *at all*.
The rest is... uhm... forgettable.
The cases look like they are in good condition, so if you don't need them you can probably resell them.

BE AWARE of trying the flash on a modern (digital) body: you should first check the voltage yourself and/or check a vintage flash voltage spreadsheet, as some reach dangerously high values (in the 200s of V) and can fry your camera/damage the hotshoe.

Depending on how much you paid for the lot it could have been a bargain or not.

[Astro-Baby]

The lens cases, if they smell mouldy, smell of trouble. They can be a breeding ground for fungal spores. A light misting of IPA and a monster hit of UV light might kill or retard it.
Many of these look like leather but in fact are cardboard with just a film of PU leather on the top so dont immerse them in water or else thay may just disintegrate.

The pentax f1.4 would be worth having so long as it doesnt have fungus or balsam seperation. The others are ho hum by my reckoning. The two beauties....well the Vivitar may possibly be repairable so long as the diaphragm blade has not creased. You would have to extract the iris mechanism and take it to bits, they are always very fiddly to mess with.

The missing diaphragm, thats game over. Are hou sure its missing ? It could just be stuck wide open due to oil contamination or other drek or maybe a disconnect inside.

As per a previous poster I am always amazed at Japanese cameras that thy never ever seemed to use any common components. Every model seems to use entirely new parts even whene theres no real need. Even bog standard parts like battery covers have different diameters, threads, depths etc even on different cameras from the same manufacturer which always seems bonkers to me.

[GUB]

Exhibit A: Cosinon 200mm F4. This one is missing a diaphragm. I shook it, looked at the front, back, shined a flash light into it. No F-stop. Nada. Can an aftermarket diaphragm be installed? It seems to take decent pictures and is otherwise ok (manual of course). Can it be repaired or should I only use it as a wide open lens and play with exposure time and ISO when taking pictures?

If it is sharp enough wide open for you to enjoy using it then just go out and use it. One less adjustment available can be great for creativity. If you feel it is a little soft wide open or perhaps lacking a little contrast then an option is to find an appropriate black washer to drop in where the iris should be. Or even simpler and very effective on a longer focal length like this lens is to cut a black paper washer that fits within the filter thread up against the front element. These lenses can bring out the creativity in you.

[Lowell Goudge]

It is a waste of time IMO to fiddle with the aperture. I tried once with a 135 macro bellows lens. If the blades are dislodged, it is almost impossible to correct the defect, which is likely worn out crimps in the blades at the hinge point, that keep them in place. It takes a tone of time to rebuild and realign the blades, and you may need to machine small pins to act as new pivots. All for a lens that you should be able to replace for $20. Maybe, and this is a risk, you could look for a badly scratched similar model and build one from the two.

Otherwise I agree with everyone else, the M50/1.4 is the only thing of value

[jatrax]

I think many of us (I certainly did) go through a stage where we think we can 'save' some old piece of gear. And sure once in a while it happens. But you need to decide if you are a photographer or an old lens fixer. The skills are not mutually exclusive but learning either well takes a long time. And time spent on one is time not spent on the other.

I didn't catch what you paid (and it doesn't matter) but you got one moderately good, manual lens, the Pentax 50mm. A quick check on an auction site shows that lens sells for between $50 and $100 depending on condition. Buying off brand, vintage lenses is a crap shoot. Unless you do extensive research you are really flying blind. You might find a gem but you have to sort through a lot of dross to find it. Far better to stick with OEM glass that is thoroughly documented and reviewed. For Pentax you can look at 3 different M42 series, then in K-mount you have K, M, A, F, FA, DA, DFA. More lenses than anyone can try in a lifetime.

If you want to learn lens repair this is a good way to get some practice, though as noted above I doubt you could actually repair these as parts are not going to be available.

[zeebanker]

Thank you all for your responses, suggestions and guidance. I now do believe that I've overpaid for the mystery box (actually I did get to see what was inside and I paid USD100). Nevertheless, its been a great experience, I learned a lot (apparently the 135mm F2.4 was made in East Germany?) about what to look for in buying used lenses and, I'll have a blast taking the lenses apart and playing with them. I intend to only keep the 50mm F1.4 and the Albinar (until I acquire a real macro lens).

Anyone want the two leather cases? I'm not sure how much they go for, but happy to let them go. Make me an offer (at least cover shipping costs . Same deal for the camera body.

[jatrax]

Also note that old flashes sometimes use very high trigger voltages. High enough to fry a modern digital camera. Do not try that flash on your camera until you have verified the trigger voltage is around 12v or less. Some used voltages over 100v.

[zeebanker]

Also note that old flashes sometimes use very high trigger voltages. High enough to fry a modern digital camera. Do not try that flash on your camera until you have verified the trigger voltage is around 12v or less. Some used voltages over 100v.

Thx Jatrax. I have a flash that I bought new with the body, so I don't intend to use it. Didn't even test it.

[jatrax]

If you have not found it yet here is the link to the Lens Database here on the forum: Pentax Lenses - Pentax Lens Reviews & Lens Database

And if you want to check that flash look here: Photo Strobe Trigger Voltages I would check myself before using but if its on this list it will give some guidance.