Recurring spot in images

[Jimmyp82]

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Hoping this is a simple one and its a dust spot on the lens (althought I can't see anything on the lens...) These crops are taken from three different film, the film before these I can't see the spot. Any ideas? All the same place on the negs.

 

 

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[69xchange]

Might be a pin hole in the curtain causing a light leak. Was the camera exposed and facing the sun with the lens wide open for an extensive period of time recently?

[Jimmyp82]

No I don't believe so... When I take the lens off is that the curtain I can see? 

[69xchange]

Yes, without film loaded, open the back door and remove the body cap. Next bring it into a dark room with a flashlight and shine the flash light into the front mount opening. From the other side ( rear ) with the door open, check for any pin hole light leaks. Advance the shutter as well to check the second curtain. 

Edited September 7, 2024 by 69xchange

[Jimmyp82]

Second curtain? How many curtains are there? Sorry this may be a really stupid question! 

[69xchange]

3 minutes ago, Jimmyp82 said:

Second curtain? How many curtains are there? Sorry this may be a really stupid question! 

Two, they travel horizontally. The width of the slit in between the two curtains is determined by your shutter speeds. The slower the shutter speed, the wider the slit is to allow longer light exposure onto the film. Anyways check the curtains in a dark room with a flashlight to determine if there are any holes in the curtain that is causing that spot in your negatives.

Edited September 7, 2024 by 69xchange

[Jimmyp82]

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Good knowledge thanks! I have a film in there now but as soon as it's done I'll check. What sucks is even if I do have a hole in the curtain due to the repair time with leica I can't see myself repairing it any time soon. Spot tool in lightroom very quickly sorts the spot but it's annoying for sure. Is it really easy to burn a hole? 

[69xchange]

1 minute ago, Jimmyp82 said:

Good knowledge thanks! I have a film in there now but as soon as it's done I'll check. What sucks is even if I do have a hole in the curtain due to the repair time with leica I can't see myself repairing it any time soon. Spot tool in lightroom very quickly sorts the spot but it's annoying for sure. Is it really easy to burn a hole? 

Yup. Easy to burn hole if the camera and a super fast lens like 1.4 is wide open and pointed at the sun. Always good practice to stop the lens down or put a cap on when not shooting. 
 

Also, is this a used camera? Which model M is it?

[Jimmyp82]

MP, had I from new along with a 35mm summicron. 

[Jimmyp82]

Well I want to finish the film before I do the test as stated above, but I did just take a macro shot with the lens off, so front side of the curtain, admittedly it wont be as clear as shining light through it, but this was done with a canon r5 and the rf 100mm macro lens with flash so pretty detailed and I couldn't see anything of note in terms of a hole or scratch etc

[69xchange]

7 minutes ago, Jimmyp82 said:

Well I want to finish the film before I do the test as stated above, but I did just take a macro shot with the lens off, so front side of the curtain, admittedly it wont be as clear as shining light through it, but this was done with a canon r5 and the rf 100mm macro lens with flash so pretty detailed and I couldn't see anything of note in terms of a hole or scratch etc

I see, you wouldn’t be able to tell with that method. It’s best to just wait till you finish the film and then do the test mentioned above. 

[earleygallery]

Definitely a pinhole in one of the curtains. You might be able to do a repair yourself, there are a few methods. Google it.

[Jimmyp82]

Will snap away some pics tomorrow and try the test. It must be very very small as on the photos it only shows as a smallish dot rather than a glowing light leak type effect. I've seen the method of repair which seems fairly straightforward, but is it really worth it when the effect of a whatever hole there might be is minimal? 

[TomB_tx]

https://www.dagcamera.com/store/p145/How_Long_Does_It_Take_To_Burn_a_Hole_in_a_Shutter_Curtain%3F.html

[Jimmyp82]

Well I used up the rest of the film, went into a pitch black room and detached the lens and opened the back up, then shone a fairly bright headlamp from front to back. Clicked the shutter and looked and wound on and looked, did this twice. I can't see anything like a bright spot, now maybe my eyes aren't the best, definitely possible! Going to get my wife to check later. But I'd imagined it would stick out fairly clearly. 

[adan]

Just for the record, with a 35 Summicron on an M4-2 (same shutter for all intents and purposes) - a low sun burned a hole in my shutter curtain in less than a minute (walking 30feet/10m between shots with the lens cap off while the lens pointed at the sun (hanging at my hip). Well, OK. I burned a pinhole in my shutter by failing to recognize the risk. 

https://www.dagcamera.com/store/p145/How_Long_Does_It_Take_To_Burn_a_Hole_in_a_Shutter_Curtain%3F.html

And a burned hole can look as black as the shutter curtain (basically, black shutter cloth/rubber turned to black charcoal at that location) and hard to see (although it may have a semi-charred brownish rim.

And need only be a small fraction of a mm in diameter (a pinhole, as in pinhole cameras) to produce a permanent hole that can fog the film in an even shorter fraction of a second (on the close order of the shutter speeds we use to expose the film also - 1/1000th of a second - or less).

It is also the case that the light leak, if present does not necessarily have to be visible - film is sensitive to cumulative exposure over minutes, hours and days. A handful of photons per minute will eventually created an exposed spot on the film. (Maybe faster - but that would depend on the ISO, and reciprocity characteristics of the specific film).

This is a basic "feature" of Leica (and some other) rangefinders cameras:

- quite scorchable rubberized-silk shutter curtains (silk is like a stronger version of cobwebs - just spun by moths). Silk scorches at 298°F/142°C)

- no SLR mirror to block focused (highly concentrated) lens light from reaching the shutter cloth in between shots (or at any time).

- the black shutter curtain absorbs light and heats up to charring temperature faster than light-colored cloth.

One reason Canon used stainless steel foil for their top-end 1950's RF shutters. (But those made a slightly louder "clack" than rubberized cloth.)

 

[Jimmyp82]

A near microscopic hole is possible if the 'burn in' dot is appearing before the image is made, as you said cumulative build up of light in between me taking a shot. So it should be much more pronounced when the time in between frames is greater in that case. 

My wife just took a look again couldn't see anything. Checked, clicked shutter, checked again, wound on, checked again, clicked shutter and checked again. Nothing visible to our eyes at least. 

Edited September 8, 2024 by Jimmyp82

[TomB_tx]

To make your eyes more sensitive do this in a darkened room after sitting in it without light for at least 5 minutes. Use a small flashlight to shine in the camera from close to the lens mount so it doesn't spoil your night vision. It could be in either of the two curtains, so check in both the wind-on and exposed shutter positions. Looks like the dot is slightly below center on the curtains.

When checking for small light leaks in my darkroom it may take 15 minutes in complete darkness before my eyes get sensitive enough to see small leaks.

Edited September 8, 2024 by TomB_tx

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[Andy_Shields]

I'd bet my life there's a hole in one of your curtains. Honestly you should be able to see it with your naked eye in a well lit room. I assume you are looking at both curtains when inspecting? It'll look like a little snag in the dead center in your case. If your camera is always advanced it'll probably be on the first curtain. If you advance only just before shooting it'll likely be on the second curtain.

[a.noctilux]

Maybe use a magnifier to inspect about/around the center of the cloth curtains.

From front and from rear.

When you see "something"put on that a dab of black ink (not much Sharpie came to mind), then try to take some pictures.