[ZombieArmy]

Just curious. If it doesn't I won't have any qualms about gluing that bad boy down, otherwise I'll try to find another solution.

[TheLens]

Why do you want to glue it? Are you trying to get manual aperture operation with a lens that doesn't have man/auto switch used on a non M42 body? If you do glue it it should still function on M42 bodies but it will be manual aperture only.

[i_trax]

why glueing ? I just bent them and push them in, you can always get them straighten and back to the original condition if needed.

[Ratcheteer]

NEVER EVER USE GLUE - the vapor will find its way inside the lens and cause yellowing

[Lowell Goudge]

There is a very simple mod, which can be made using a 3 mm section out of a plastic tube like that of a ball point pen refil.

You remove the lens mount and slide the tube over the pin between the internal flat plate the pin operates,many the lens mount.

This mod is completely reversible.


In some lenses you can even do this with out removing the mount, because you can see the interior side of the pin and with a slit open the tube slide it over

[Lowell Goudge]

Try this modification
https://www.pentaxforums.com/forums/58-troubleshooting-beginner-help/115841-a...ml#post1199619

[vonBaloney]

NEVER EVER USE GLUE - the vapor will find its way inside the lens and cause yellowing

Typical super glue (I use the thick gel type) will not as long as it is well-ventilated while it dries. (Once dry it is perfectly fine, even on internal parts.) And it wouldn't be yellowing, but a fogging. Gluing the pin down on most lenses works fine and is usually reversible with a drop of acetone. (But I wouldn't glue it if you ever thought you were gonna reverse it as acetone will melt some plastic surfaces so you must be careful.) I've glued lots of them -- cheap lenses that I'm going to keep forever or that have mounts that are difficult or just not worth bothering with opening up and trying to stick sleeves on, etc. There seems to be a paranoia about using glue but if it is ok with you glue is quick (to apply, you must wait for it to dry) and easy and isn't going to harm the lens. Anything involving removing the mount or bending things is actually more risky and easier to bungle.

Certain lenses ARE super easy to alter the mount, so usually it is just a matter of checking Google. But others are very difficult to get the mount off or do anything internally, personally I just glue it and be done with it. Never had a problem, I use those lenses often.

Another word about "reversible" -- even if it is easy to undo what you did, if you have a pin that has been held down for months or years, don't expect it to work just as good as new when you finally release it. These are decades old lenses -- the spring will lose tension. These should be considered permanent alterations. If you want to use the thing on an old m42 camera body with the auto-aperture function intact, then don't alter it, simple as that. If you're going to mod it, just leave it modded, even if you sell it later -- most buyers will want it that way anyway and the ones that don't won't want one that was artificially pinned down for who knows how long and later "reversed"...

[pacerr]

NEVER EVER USE GLUE - the vapor will find its way inside the lens and cause yellowing

Hmmm . . . I've been gluing photo, optical and electronic gear for . . . oh, about 40 years now and NEVER EVER had a problem with it. Of course appropriate, prudent choice of glues, applications and ventilation helps. Know your tools!

Here's another personally tried and true glue option: A drop of a melted piece of low-temp, hot glue gun stick applied with a tooth-pick, allowed to cool and trimmed as necessary with a sharp blade makes a semi-permanent pin fix. Can also be used to hold parts in position for trial fittings for metal and most plastic parts.

Contact cement - the kind you allow to dry for a few minutes before joining the parts - works fine for more permanent applications. Lots of external body trim, light-masking kits and lens rings applied that way even at the factory.

[Ratcheteer]

Hmmm . . . I've been gluing photo, optical

ever wonder why some vintage lens have yellowed even though they don't contain thorium (some east german optics manufacturers were next door to glue factories)

if your confident in your skills and sure you know your glue's good for you, but everyone else caution

on a side note the Mitakon 50mm f0.95 you can buy new off ebay is radioactive (Contains Lanthanum)

[bar_foo]

on a side note the Mitakon 50mm f0.95 you can buy new off ebay is radioactive (Contains Lanthanum)

Lots of stuff contains Lanthanum; if that's your concern you also need to avoid the glass used in fibre optics and most Nickel-Metal Hydride batteries. Most things are radioactive (your body, for instance, with its C14). The issue is the kind and degree of radioactivity.

[pacerr]

. . . some vintage lens have yellowed even though they don't contain thorium (some east german optics manufacturers were next door to glue factories)

What ELSE were they next door to? A dairy farm perhaps? Down wind of what other environmental contamination source(s)? What sort of vintage glue? What scientific evidence links proximity to a glue factory with lens yellowing while eliminating all other casual factors? Are there similar circumstances noted in Patagonia and Pittsburg, or just East German examples?

An individual observing "yellowing" of a lens coincident to the use of an unspecified glue on (or perhaps just nearby?) a lens without eliminating other causes in a repetitive, scientifically repeatable manner doesn't warrant a NEVER EVER caution statement IMO.

Practical personal experience and recommendations by others with a verifiable, credible history of success seems a prudent enough path to me.

[stevebrot]

NEVER EVER USE GLUE - the vapor will find its way inside the lens and cause yellowing

That is a new one for me. Do you have a reference? There are issues related to cement solvents and/or curing vapors*, but yellowing has never been on the list as far as I know.

FWIW, yellowing is usually blamed on:

• Changes to the glass due to radioactive decay --or--
• Use of poor quality balsam cement for grouped elements that discolors with age --or--
• Use of glass with a color cast

Steve

* particularly the curing vapors of cyanoacrylate cement (Super Glue). Those vapors can craze plastic optical elements (think aspheric elements), focus screens, and viewfinder oculars some distance from the point of appliation. I have a very nice Yashica rangefinder camera what was ruined by super glue being applied some distance from the viewfinder that is now opaque. Camera repair techs regularly use various glues and cements, but the list is a short one.

[Ratcheteer]

Lots of stuff contains Lanthanum

you would think chinese manufacturer would use cheaper materials, growing then grinding lanthanum fluoride crystals into flint and crown elements is not a cheap process.
and this lens has 4 elements made of it (speedmaster version 1)

and the price at least 50% cheaper than slrmagic's offering, 70% cheaper than the cosina/voigtlander Nokton (witch has recently been discontinued so expect it to go up) and about 1/8 the price of a second hand leica noctilux

That is a new one for me. Do you have a reference? There are issues related to cement solvents and/or curing vapors*, but yellowing has never been on the list as far as I know.

sorry should of used the word fogging (which is far worse) than yellowing

[stevebrot]

sorry should of used the word fogging (which is far worse) than yellowing

Yes! Far, far worse!


Steve