Monthly Archives: May 2017

Separation, leads to divorce, and a new coupling.

Sometimes you encounter a lens that has some internal blemishes that you cannot seem to clean off … can look like rainbow rings (ring of fire), a cloudy ring round the edge, a crescent beige tint, bubbles, or even a flowery/snowflake pattern … and it always seems like it’s trapped between two lens elements.

This old LTM lens has an almost complete ring haze. Now, it could possibly be just haze on the back of the element … but I suspected it was more than that.  After talking it apart it was apparent that it was separation of the front two elements.

Yes, in fact it is between two lens elements. Most lens designs require two lens elements to be bonded/cemented together (doublet) with adhesive to eliminate the glass air gap. By reducing exposed surfaces, cementing reduces refraction and ghost images from reflections, and allows the use of thinner flint elements. 

Older lenses used Canada Balsam as it had a high index of refraction, which is optically a good thing to have. It is derived from good ol Canadian trees … yup good ol sap … yes, its not just only for maple syrup.

Development of resins to cement elements started in 1785. Eventually changed to a synthetic resin because of WWII … high altitude aerial photography caused issues with Canada balsalm, so they developed a synthetic cement that could handle low and high temperatures … this is the MIL-A-3920 standard optical adhesive. UV curing adhesives appeared in 1966 to reduce the curing time for high production.

When the “cement” has degraded and no longer seals the two elements together, the separation will create artifacts that will change the refractive properties of the lens. Sometimes it is not very visually apparent … sometimes it is. The only real solution is to separate and re-cement them.

This topic has been discussed much on the web … FotomozaicLargeFormatForumskgrimes

With Canada balsam, it requires heating to soften the resin so the elements can be separated. The newer synthetic resins require special chemicals … and in some cases the elements cannot be separated without damaging it.

Once separated, new resin can be applied to cement the elements. Then new resin can be applied to cement the elements … modern day resins are UV cured, so makes it much quicker to get a lens back to working condition.

Sounds easy … not !!! Heating sometimes does not work, or even worse causes the element to crack … and there are cemented group that are encased in a metal sleeve which has to be removed first (without damaging the glass, and you may have to find something to replace it) … or, as mentioned before, it just doesn’t work.

One day I will make a serious attempt at re-cementing … meaning, my half-ass attempt sucked, and I will try again.

Summers Optical makes many different types of synthetic resins for optical cementing … and you can still buy Canada Balsam, as it is still used for microscopic slide mounting and painting.

Sometimes the lens separation is not so bad in terms of affecting the image, especially if it is around the edges like the lens pictured above … but when it sits right in the centre, it will most likely cause apparent visual effects. Mounting this lens on my Sony NEX-6 and taking some shots, I could not really notice it until I got some light hitting the front and the separation starts adding some flaring/fogging.

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Yashica Mat-124 G … winder side, not side-winder.

This camera has a problem with setting the shutter. A complete wind does not set it, so you can never take a picture … hmm, sounds like something is not coupling correctly.

The first thing you have to do … and you already know this … is to remove the leatherette. Take off the one back/strap holder arm before removing. With the one that I have here it was fairly easy to peel the leatherette off without damaging it. Take your time.

Push out the winding arm pin. Remove the arm and the four items that go with it.

Now you can unscrew the plate.

The rotary disc for the winding arm it attached with a circular nut.

Note the position of the golden arm.

Unscrew it and remove the stuff underneath it.

 

Remove the spring from the counter reverse lever (right), remove screw and take out arm.

Remove the 12/24 exp indicator plate, first pull off the two springs.

Pull out the silver gear.

The counter change gear arm (bottom) is the next to go.

The counter dial has a spring loaded screw in the middle. Take that off with the dial and the dial plate underneath it.

 

 

 

The counter reverse lever (top) is held on by one screw on the right. Slightly lift the arm on the left to pop it off for removal.

One screw holds the winding stopper arm (centre) , and you should release one arm of the spring.

The middle golden gear (bottom) has one pin screw in the middle that is unscrewed clockwise … very important.

 

 

 

Now you can remove the winding assembly by taking out the four screws.

Now you can see the shutter cocking arm … and in my case it is bent upwards. This means that it will never push down to its full distance.

You can try to rebend it back into shape.

If you want to take that part out you will need to remove the front lens/shutter component.

Here is my bad attempt at bending the arm down … which actually caused more metal fatigue, so when I put it back in it bent itself out of shape again.

Note: on the back side of this part is a riveted switch that prevents double exposures … do not damage this part, as it will cause a lot of headaches. If this part does not freely move, the winder will be in a locked position after the shutter is released. I am guessing this is why some people force the winder and bend the arm.

As I mentioned before, the Yashica Mat-EM has the exact same part (just not golden) so you can just replace it.

When putting back together you should be very careful that the arm is positioned above the shutter release mechanism.

You will also need to reload the spring on the counter dial. If the counter dial is not spinning freely, then loosing the screw and move the dial around so it sits properly.

… and be aware of the little springs that are all over the place.


Yashica … MAT-124G … flaw ?

Out of all the TLR’s out there, I’ve noticed that the Yashica MAT-124G is one of the most sought after cameras … even more than the Rollei because it is more affordable (hmm, actually all TLR’s are more affordable than Rollei’s).

The G, is the moderized/improved version of the plain old 124/12/24. The G refers to the addition of gold contacts in the meter. Some parts were changed from metal to plastic, and the chrome is covered in black paint … to make it a darker camera. In terms of IQ, it has the same optical components as the other models … so don’t think the G is the best Yashica TLR in that respect, especially when the price of the G can be much higher.

You can read more at the yashicatlr.com site.

In my repair of this camera I came upon a subject that has been mentioned on the web before … incomplete shutter cocking. After taking it apart and doing a lot of mental battles about how the mechanisms work/interact, I came to the “personal” conclusion that there is a design flaw with the newer winding mechanism.

The shutter cocking plate has an elbow that is pushed down by another arm that is connected to the winder cam plate. As the cam plate rotates it pushes/pulls the shutter cocking arm … this arm pushes down to rotate the shutter cocking plate. The problem I have with the design is how high the elbow sits … it seems to me that they placed it too high … and since the shutter cocking plate moves in a circular motion and the shutter cocking arm moves in a linear motion it (the arm) requires most of its force when starting the movement from its highest position.

Now this all works fine when the camera parts are all in original condition, but I think after some time the arm has a greater chance to become stressed (typically when some users unfamiliar with the camera, force the winder when they shouldn’t). Once the arm is bent it will no longer be able to obtain the full motion to complete the shutter cocking … and it does not take much deviance in the arm … and once the metal gets fatigued it will continue to bend out of shape easier … and even after it is straightened (as the straightening process placed additional fatigue on it) it will continue to do so.

The image (in my repair post) shows my sad attempt at straightening the arm … it’s riveted in place which made it not so easy.

Now … to the good news. I made a guess … yes I still have brain cells that can do that … based on the number of Yashica TLR’s I’ve taken apart, the parts appear to be the same. The Yashica-mat EM that I just repaired (and nobody wanted to buy) now became a parts camera … and my guess is right, same part. I think the E, LM, EM, 12, 24, and 124(G) share most the same mechanical parts.


There be knobs !!

There was one particular “tool” that I mentioned that could be one of the most important ones to have … or have access to … and that is a friend who has a machine shop.

I had completed the work on the Mamiya Six some time ago, but sadly the camera came to me with a missing part … one of the film spool supporters.

I thought, hmmm, possibly my awesome friend Craig could machine a new one for me … and that’s what he did.

The old one is on the right.

It’ not an exact replica, but I was not expecting that, just something similar.

Hey, it works … and looking almost like it’s original is a bonus !!


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