What could have caused this? Portra 400

[BrianShaw]

Thanks. As I said I have no experience of non auto-rewind cameras - well a Yashicamat many years ago but I may have never rewound it backwards -well not unless the rewind action was nearly as easy as the correct way and by all accounts from others here this seems unlikely. So based on everything you describe in terms of what you did and the user did I am left with a nagging doubt about why neither of you noticed anything difficult unless it indicates that the rewind backwards may not have been the cause

pentaxuser

I 'm not doubting, but puzzled... I have never experienced this "wound backward" experience or phenomemon.

Doesn't film on that Minolta, and every Nikon I use, always get bent in the opposite twist direction when it gets pulled onto the takeup spool... I think so. Why is winding backward any more of a bend than that?

 

[pbromaghin]

I 'm not doubting, but puzzled... I have never experienced this "wound backward" experience or phenomemon.

Doesn't film on that Minolta, and every Nikon I use, always get bent in the opposite twist direction when it gets pulled onto the takeup spool... I think so. Why is winding backward any more of a bend than that?

I was going to ask the same question regarding Minoltas.

 

[Donald Qualls]

Hell, that makes me feel old.

Yep, me too. I learned to rewind 35 mm film in 1969. Summer camp, borrowed Yashica rangefinder (don't recall what model, it was almost fifty-five years ago, after all). I've used or owned a couple power rewind P&S cameras, but the ones I use most now don't even have a crank, just a knurled knob.

 

[MattKing]

Picture the path of film in a properly operating 35mm feed cassette. The film is coming off the edge of the roll and heading straight out the felt loaded exit slit.
The it gets to the end of the roll - it is stopped and winding further just adds tension to the film affixed to the spool.
So you click the rewind button and go to rewind the film - probably by turning the crank in a counter-clockwise direction. That causes the film to be smoothly rewound in the opposite direction from how it was fed - smoothly through the slit and straight on to the outside of the building rewound roll inside the cassette - emulsion facing toward the centre of the spool, just as it was before you put it into the camera. Great, no stress.
But if instead you rewind in a counter-clockwise direction, you will be pulling the film down across the cassettes slits edge, and then on to the spool with a reverse curl - with emulsion facing out, rather than in.

 

[reddesert]

It's got to be pulling sharply over the cassette inside edge, not the reverse curl itself, that is the problem. Film is flexible, and gets wound in the reverse direction on many takeup spools, but the takeup spool has a nice smooth radius unlike the cassette inside edge.

 

[snusmumriken]

Picture the path of film in a properly operating 35mm feed cassette. The film is coming off the edge of the roll and heading straight out the felt loaded exit slit.
The it gets to the end of the roll - it is stopped and winding further just adds tension to the film affixed to the spool.
So you click the rewind button and go to rewind the film - probably by turning the crank in a counter-clockwise direction. That causes the film to be smoothly rewound in the opposite direction from how it was fed - smoothly through the slit and straight on to the outside of the building rewound roll inside the cassette - emulsion facing toward the centre of the spool, just as it was before you put it into the camera. Great, no stress.
But if instead you rewind in a counter-clockwise direction, you will be pulling the film down across the cassettes slits edge, and then on to the spool with a reverse curl - with emulsion facing out, rather than in.

Erm, haven’t you got clockwise and counterclockwise reversed, Matt? Or am I being stupid?
You are not stupid. I must have been looking at a mirror when I was thinking of this .
Thanks - It is fixed now.

 

[MattKing]

It's got to be pulling sharply over the cassette inside edge, not the reverse curl itself, that is the problem. Film is flexible, and gets wound in the reverse direction on many takeup spools, but the takeup spool has a nice smooth radius unlike the cassette inside edge.

Probably, but I could also see it bunching up a bit inside the cassette, in protest against the backwards winding.

 

[foc]

This might help explain how stress marks appear.

 

[MattKing]

Thankyou - I was looking for a graphic like that!

 

[snusmumriken]

This might help explain how stress marks appear.

View attachment 334894

I’ve learned a new word: ‘paster’. Does that refer to a bit of tape, or to those loose bits of plastic that grip a projection on the film?

 

[foc]

Thankyou - I was looking for a graphic like that!

You are welcome.

Sometimes an image and some text is the best way to explain something.

 

[foc]

I’ve learned a new word: ‘paster’. Does that refer to a bit of tape, or to those loose bits of plastic that grip a projection on the film?

Since it is an Eastman Kodak graphic, I would assume that the "paster" is the tape used to attach the film end to the spool in Kodak cassettes.

 

[M-88]

Thanks. As I said I have no experience of non auto-rewind cameras

And now I'm curious which Pentax do you use, an auto-rewind 35 mm or straight-up Pentax 645/67?