M42 aperture pin question

[jito]

So I bought a few m42 lenses.
Some have an aperture pin (that's what I read on wikipedia, I wouldn't know what that is otherwise), I'm not quite sure what to do about it as it seems to prevent the aperture blades from closing.
My m42 to eos adapter presses the pin down but not all the way down.

I think I would preffer to open the lens and remove the pin. It shouldn't bee that much of a big deal, is it?
I recall a topic talking about this but I can't find it. Could anyone point me the right direction or give me tips on how to remove it?

[peterqd]

Hello and welcome.

The pin is used by old M42 cameras to close the the aperture blades "automatically" at the instant the shutter fires. This allows wide-open focussing. These cameras have a bar inside the camera mount that pushes in the pin and this closes the blades to the setting you have selected. So removing the pin won't force the blades to close, it will prevent you from ever closing them!

Does the lens have a sliding switch marked A-M or (rarely) O-C? IF so, slide this so that M or C is visible. This puts the lens into manual mode and the blades should open and close as you alter the dial. If it doesn't have a switch then there are ways of adapting the pin to remain depressed. What lens is it please?

[hoanpham]

fujinon m42 lenses have only auto mode. It is possible to convert (reversible) to manual mode. I have done for all my fujinon and m42 with no A-M switch.

You open up the rear, cut a 2mm plastic tube from a q-tip or electrical wire, and insert into the pin to prevent it sticking out.

I got help from this forum for info.

[Ymmot]

What you are probably referring to is the modification of russian helios lenses without A/M switch. They sometimes remove the mount and add a sleeve of wire insulation or the round hollow part of a q-tip around the pin on the inside such that it remains depressed. I have also seen people bending pins and shoving them in or glueing with superglue (really bad ideas ).
So unless you really dont want to sell your lenses anymore or you are comfortable with small mechanics and opening lenses, there is too much margin for error to destroy a perfectly good lens. Note that i have never done this, first check for A/M switches.

As you mention that your adapter does press the pin but not enough i would say you do have an adapter with a flange for doing this (they also come without), so maybe the simplest solution is to find some thin rigid flat plastic less than 1mm thick or something similar (cardboard or paper might release fiber so watch out with that) and cut some rings that you could insert between the lens and the adapter (on top of the flange for pressing the pin of course, not on the outside ). Dont make them to thick or add too many, as then you will not have infinity anymore.

[Lloydy]

http://chris.stingray.free.fr/Tuto/Modif_H44M4/Pinoche_H44M-4.html

This is a good description of modifying the Helios by sleeving the aperture pin, other lenses will be different but not hugely. It's not a difficult procedure.

[kansalliskala]

[ramiller500]

If the lens is cheap and readily available, why not superglue the pin to keep it depressed, if you need that? You can buy a duplicate, unglued lens.

Make sure to keep the glue off your hands and other parts of the lens.

[Attila]

In a machinery shop you can order a simple ring what is fit into your m42 adapter and you will have an adapter with flange which is press pin on any lens pushed. I have this kind of adapter and don't need to ruin any lens.

[luisalegria]

Ditto with Attila and Ymmot -

Best to get an M42 adapter that presses the pin properly. They exist on ebay, they are cheap and they solve the problem completely.

[edz]

Word of caution: my adapter (m42 -> m4/3) had a ring/lip which interfered with an aperture tab on one of my lenses so I had to increase the hole's diameter slightly.

[MalcolmL]

This is a semi - permanent fix for digital:

1) with some strong wire cutters clip the end off the pin
2) Choose a small screw tha just gains traction in the shaft for the pin (say from an old lens you have dismantled)
3) Stop aperture down fully (this will prest the aperture only)
4) Screw your screw into shaft until aperture is full stopped down and a little more (say 1/4 turn of screw)
DO NOT OVERTIGHTEN SCREW AS YOU MAY BUST THE STOP DOWN LINKAGES
Test mechanism.
This takes 10 minutes and always works. No need to open lens. But the lens will never auto stop down again unless a new pin is inserted. make sure your screw is not too long as it may imapact on the camera's contact pins or mechanical components just inside your lens mount.
It is a good fix. I personally dont like superglue.
Malcolm

[jito]

Hey all,
thank you for the replies.

The lens is an hanimex MC 28mm f2.8. I got it really cheap together with a vivitar 200mm.

The aperture ring was not working at all, whether I press the pin or not.

I was too curios, I decided to open it. Turn out that when the pin is pressed, there is a lever that pulls a spring around the core piece. That pring is long and it's supposed to pull the aperture blades. Problem is, that spring got relaxed and doesn't have enough pull to move the bladse. Particularly when the lens is assembled (the body of the lens set up appears to add some extra friction to the blades).

If I move the aperture ring so it stays on the lowest possible aperture (highest F number) and press the pin, I can see the blades moving, but for most of the aperture range, the pull is simply not enough.

I'm not sure I'll be able to fix this lens or even put it together for that mater. I guess I could put it back together without the aperture blades so it would stay always wide open, but that's very lame.

One thing I noticed is the amount of tiny pieces and how fragile the whole thing is. This is kind making me keep off auto M42 lens. This is simply prone to fail and malfunction. I'm guessing the fully manual m42 lens have a more robust build. Can anyone confirm or correct this?

I'm using a cheap set of watchmaker screwdrivers. They are not suited for such duty, I have a hard time applying the necessary torque. Could some one recommend me a cheap set of screw drivers and other tools used to repair camera lens? I don't really know what to search for on ebay.

[luisalegria]

Some lenses are more robustly built than others. There are possible problems with preset lenses also.

Usually the older they are the sturdier they are, also the name brands are better made.

Pentax Takumar M42 lenses have excellent mechanics, I never saw one yet with a gummed blades or weak spring problem.
Ricoh, Mamiya, Vivitar and Soligor lenses are pretty good. Vivitar and Soligor sourced from many manufacturers but mostly these are well made.

The problem with yours probably isn't really a weak spring but old lubricant on the aperture blades that makes them stick. This is more resistance than the springs can handle. The easiest fix is to put some lighter fluid (Naptha) on them, you will probably see them magically start working. The difficulty here is that as soon as the lighter fluid dries the problem will come back. You must patiently work the aperture while putting in more lighter fluid, and while its wet wiping the blades off with a cotton q-tip to remove the dissolved oil. After several treatments most of the oil will be removed and it should be working normally.

[fuzzywuzzy]

[kansalliskala]

[peterqd]

Hanimex..... hmmm

This was a cheap and poor quality brand in my younger days, and I would expect that it's probably not worth the effort of repairing it when you can buy top brands so cheaply these days. Use it for practising repairs by all means, but I would advise you look for a better quality lens.

If you particularly want a cheap M42, one of the Helios 44 versions would be no more expensive but far better quality.

[jito]

Post

@fuzzywuzzy Except for the color, that looks exactly like mine, same ebay seller and everything. One thing I've noticed is that the screw thread doesn't have the same length across lenses. The diameter is the same, but some lenses have more turns tan others. I haven't tried many 'auto' m42 lenses, but I doubt an adaptor will be able to perform equally on all of them. I'm not sure how old cameras got this right, I guess they used some kind of harder spring to press the pin.

I took a few test pictures wide open and they looked ok. Nothing too impressive, I would say it has similar performance to my canon 18-55 it lens at 28mm, which is not bad but a bit boring so to speak.

I am indeed using this for repair practising and learning. Don't we all like to break stuff ? I certainly do.

@peterqd The helios44 (according to a quick google search) is a 58mm lens. I was looking for something that would capture more wide angle for landscapes and the like. But I'm open to more suggestions from the soviet union.

It's the first time I open a lens, I don't know if the build is cheap, it definitely doesn't feel robust.

Another thing I don't get is why do lens come with a set of discrete aperture values instead simply allowing the user to freely rotate the ring. This lens has a few dents on the inside of the aperture ring and a deeper dent on the lens barrel where a tiny metal sphere sits. If we rotate the aperture ring, the sphere will sit between the barrel dent and a different aperture ring dent. Ok, this does look cheap.

Anyway, after I get a decent set of screwdrivers I will make these modifications (more like shortcuts) if I can:
1. remove the sphere (continuous aperture selection)
2. remove the whole 'auto mechanism'. Dimmer focusing but at 28mm this should hardly be a problem

[luisalegria]

Continuous aperture without "clicks" was not an advantage to users of SLR's back in the old days.

You wanted the aperture to stay where you set it, without the "clicks" it could be moved accidentally without realizing it, by your hand when you were focusing perhaps, and there wasn't any AV mode to cover the mistake ! Its also good to be able to feel the stops while looking through the finder at the meter while adjusting exposure, etc.

Most old 35mm lenses have the same construction you describe on your Hanimex, with the dents/grooves and the little ball, even the highest quality models of their time.

Many of the better makes had aperture clicks in between full stops to give a little finer control but I don't think this is very useful.

[peterqd]

Of course, the best type of lens if you want a "clickless" aperture setting is a preset type, such as the Helios 44-2 or if you want wider, a Mir 1B (37mm). With these lenses you set the smallest aperture you require with one ring (which does have clicks) and open and close the blades to that setting with another ring which rotates freely. On old cameras this was useful for focussing wide open and then stopping down to your chosen setting without needing to remove your eye from the viewfinder. On modern cameras with AE, they are fun to use because you can set them at the smallest aperture permanently and use the stop-down ring to control the shutter speed and depth of field, a kind of bokeh control!

If you want wider than 58mm and a free aperture control, the Mir 1B is a great choice. USSR lenses were still being manufactured in what we in the west would consider old-fashioned designs right up till recently (and still are in some cases). If you want really cheap, you could look for old pre-set wide angle lenses such as Optomax or Soligor etc but remember they were obsolete many years ago so they're going to be very old.

[DSG]

M42-Sigma SA adapters have almost always had a built in flange to compress the AA pin, long before M42-EF adapters did.
The first M42-SA adapter to hit the market just after the SD9 was released was the CSM42, from about 2003, which had no flange but this was followed by the CSM422 which was the first version with the flange. Both were made to very high quality but were quite expensive, costing about £50 ($80). Later, when these were discontinued, the Japanese JTAT company started producing their version, which is still available and for the same price. It was'nt long before cheaper Polish made adapters were available...Initially the first batch came without the flange but thereafter they all had the flange. The Polish made versions are made from anodised Aluminium, instead of the usual Chrome plated Brass and are available in Black or Silver finish. They cost about half as much as the JTAT version. The Polish guy actually did a brief run of Chrome plated Brass adapters too, and these cost about £35 each but as soon as they were all sold he continued production of the anodised Aluminium versions only.
Now we have to contend with the commercial might of China...Who seeing the similarity between the SA mount and the PK mount, have started to flood the market with very cheap Chrome plated Brass versions, costing about £5-£7...The problem is, they are little more than modified M42-PK adapters, so they are noticably shallower than proper M42-SA adapters, effecting both the accuracy of the lenses focus scale and the ability to reach infinity focus correctly, if at all (the Chinese adapters, being shallower, can allow the rear elements of some M42 lenses to hit the dust protector before infinity can be reached), and none of them contain the necessary AA pin compressor flange, making them totally useless with many M42 lenses.
I can speak from experience because I have a CSM422, a JTAT version, a Polish black anodised Aluminium version, a Polish Chrome plated Brass version and I even bought two of the Chinese versions to try out, just because they were so cheap.
Its frustrating seeing EF versions, with the flange, and even with an AF confirm chip, going for about the same price as Chinese M42-SA adapters which dont have the flange , but my next camera will probably be a Canon so I plan to take full advantage of this

[peterqd]

We've discussed adapetrs with or without flanges extensively in the past. If you have an "Auto" M42 lens without an Auto-Manual switch then you need to use a flanged adapter or find some other way of depressing the pin. Otherwise, if you do have an A-M switch, it is better to use a non-flanged adapter and set the switch to manual.

Some flanged adapters can prevent the lens from screwing fully into the adapter because of protrusions on the rear of the lens. This example shows the protrusions on a S-M-C Takumar 3.5/28 binding on the flange of a chipped adapter, and the lens fitted on a non-flanged adapter. In this case the lens will not screw completely home in the chipped adapter, and the aperture dial is jammed because the lever is binding on the flange.


And in this picture the rear element of a Super-Takumar 1.4/50 jams in the hole in the adapter before the infinity stop is reached.

[DSG]

[uttam.hathi]

the best way is to do a tedious autopin fix without damaging and keeping it reversible.
I have done that for my unsung but a great Voigtlander ultron 50 1.8:
the link
https://www.flickr.com/photos/34859797@N07/sets/72157639638310116/