Solving Travis's streak problem

[sait_akkirman]

I am repeating my reply here because I have had this problem

with more than 1 Leica body. I think it is another important Leica

problem that should be known. Specially if you are testing to buy

a new or second hand body. The problem is streaks parallel to

the long side of film manifesting themselves mainly at 1/1000

sec (sometimes at 1/500), and specially noticable when you

have an even subject matter like blue sky.

"Travis, I know exactly what the problem is, because I have had it

too in exactly the same place. It happens when the edge of one

of the blinds (the metal strips) is not absolutely straight and

smooth up and down. It happens mainly at 1/1000 and

sometimes at 1/500 depending on subject matter. At 1/1000 the

shutter slit is very narrow, and where there is any imperfection on

the metal edges (e,g. like a pimple sticking out) that spot causes

slightly less exposure at that height on the film. As the shutter

travels across the film this manifests it self as a darker (less

exposed) strip on the film. At slower speeds the shutter slit is

wider, so the proportion of the "pimple" to the size of the slit is

much smaller, so it does not show itself as an exposure

difference. The fact that streaks are strong on one side and they

dissapear towards the other is because your slit is uneven from

left to right. I f you make tests you will probably find that at 1/1000

one side of your frame is darker than the other side due to

unequal shutter blind travek speeds. If all this does not make

sense, get in touch with me. "

[jackflesher]

Seems to me since the shutter travels horizonatally in the M that

a "pimple" on the side of one of the curtains would create a

horizontal streak on the film, not the vertical streaking Travis

had...

[randy_samos1]

The example that Travis provided was from the camera being held to do

a portrait format shot. The streaks are horizontal in the frame.

<p>

/r

[sait_akkirman]

Thanks Randy.

[randy_samos1]

You're welcome Sait.

<p>

Earlier on in this thread, I was trying to say what you just did, but

had to speak from lack of experience. I've seen/heard of this problem

LOTS of times with Horizon panoramic cameras, but I had expected the

machining on the Leica shutter to be a large cut above that little

overrated gem.

<p>

I'm a bit dissapointed to find out I was wrong in that assumption. :(

<p>

/r

[travis2]

Thx Sait.

 

<p>

 

Jack, the streaks run PARALLEL to the length of film in all problem

pics. So, the BUMP ON SHUTTER EDGE theory HOLDS.

 

<p>

 

 

Just to clarify that I understood what Michael, Randy and Sait said

earlier in my thread

 

<p>

 

 

I believe that if there is a BUMP on the upper shutter edge of one of

the curtain cloth, then as the shutter slit travels across the film,

the track of streaks will be formed in line with where the BUMP spot

is, BECOS LIGHT WILL BE BLOCKED. aM i RIGHT?

 

<p>

 

SO, according to my pics, I think there are a FEW BUMPS on the upper

edge.

 

<p>

 

I hope i know what I just said!;))

[travis2]

Question is, if there are BUMPS, how do I pry open the two shutter

and then smoothen the edges???

 

<p>

 

damn.;)

[travis2]

Sait, I seriously think you have gotten the REASON for the streak

problem. How did you learn of this, and what did u do to correct it?

 

<p>

 

 

It seems very logical, the bump/pimple theory.

 

<p>

 

Randy, credit goes to u too! Brilliant.

[sait_akkirman]

Travis, when the problem shows at the top of the neg, (don't

forget that the film is travelling upside down in the gate), you

really have to look at the lower portions of your curtains. If the

problem is on the following curtain edge it is easy to check - you

turn the speed to "B" setting, without a lens on the body, push the

button to let the first curtain go then put a pencil, or similar thing

into the open gate and let the second curtain loose and let it

settle against the pencil. Now look at the edge from both the

back and the lens sides of the camera with a magnifier to find

the imperfections. (I do not accept any responsibility for this

suggestion if anything goes wrong). If the problem is on the first

curtain then I am afraid it is a repair persons to dismantle the

whole thing and check the curtain edge. The repair has been

done successfully on my particular camera.

[sait_akkirman]

Repair should be done by someone qualified. Settling for a

lower 1/1000 actual speed (eg 1/700) might also ease the

problem as the slit then will be wider.......

[travis2]

Sait, got it.

 

<p>

 

Thx for finally solving the mystery.

 

<p>

 

Really appreciate it.;)

 

<p>

 

At least I know now why I had to part with it.