Camera or film problem?

[mjs1973]

A friend of mine has a Minolta film camera (not a cheap p&s) and asked me about a problem that he has had with it. He said that he put in a new roll of film, took about 8 shots, and it rewond the film. He put in another new roll of film, took 2 shots, and it rewond the film again. The next roll he used, worked fine. So could it be a film related problem, such as something wrong with the DX code on the canister, or does it sound more like a camera problem? He is using a consumre grade Kodak color print film. Sorry for the lack of details but that is all I have.

[Outdoorsman]

A friend of mine has a Minolta film camera (not a cheap p&s) and asked me about a problem that he has had with it. He said that he put in a new roll of film, took about 8 shots, and it rewond the film. He put in another new roll of film, took 2 shots, and it rewond the film again. The next roll he used, worked fine. So could it be a film related problem, such as something wrong with the DX code on the canister, or does it sound more like a camera problem? He is using a consumre grade Kodak color print film. Sorry for the lack of details but that is all I have.

Hmm, this sounds like a good call for the "Camera Talk" guys! If they existed, that is.
This is what I know, so if I'm wrong, let anyone correct me!
The camera should sense the end of the roll by tension, which explains the mystery (to some) why some rolls have an extra frame or two at the end. The camera doesn't know whether the roll is an 8-exposure, 24-exposure, or even 36-exposure roll. When the roll physically runs out, then the camera automatically rewinds. With some people using custom length bulk rolls, you can't make a camera that rewinds after a set number of exposures.
If the camera is rewinding early, then it must be sensing tension on the film. This could be due to a sticky roll, or it could be due to the camera hanging internally, like gears sticking or rollers sticking.
This has never happened to me, so I couldn't say from any experience what it is. Have him try a different film brand, just to be sure. If the problem continues, then the camera should go in for service.
Hope this helps...

[mjs1973]

Thanks for the advice. I didn't know how the camera knew when you got to the end of a roll, I always assumed that it was something written into the DX coding on the film canister. I learned something new! Thanks, I will let him know.

[drg]

First, the ISO DX encoding on your canisters contains three basic items:

1. ISO speed (i.e. 160, 800, 1600 etc.)
2. Number of exposures
3. Film Exposure Latitude. (how many stops of range for print film)

Not all cameras read anything but the speed number. And some older/earlier DX capable cameras read only a limited range for the ISO number.

Inside the camera where the film tucks in, if you only see four contacts, it is only reading the film speed and ignoring the rest of the data. In this case, the camera is probably looking for a change in tension, or if it can't advance the film it rewinds (which may be what is going on with your friends camera).

Most of the later SLR's (virtually everbody, mid 90's on) read the exposure count as well. On cameras that sense this data you will see an offset second row of sensors in the film well and there may be up to 5 or 6 more contacts. There are power contacts as well which I'm not including in the count.

These cameras DO KNOW how long the film is and there are a few cameras that have overides and the ability to do stuff like advance to a particular frame (for mid roll rewind and reloading).

If the Minolta in question is one that has the program card system, the cards can be damaged and not work properly and force rewind. With the cards removed there should be defaults that come into play and that will quickly tell you if that's the problem. If the film after being rewound leaves the film out (the leader) then it's a programmed function and needs to be reset. Unless you want the leader out, again mid-roll change/multiexposure/test strips etc.

If the camera has been used in less than optimum conditions (read this as too much dust or humidity) the sensors may be dirty or corroded.

First, change the batteries to brand new fresh ones and see what happens. Low batteries in a camera with the processing going on that is traditional with Minolta Bodies will cause all kinds of grief. As I mentioned earlier, if the tension is wrong (and low batteries change the feedback from the servo/rewind motor) they will by default rewind.

Let us know what you find!

[Franglais]

....

First, change the batteries to brand new fresh ones and see what happens. Low batteries in a camera with the processing going on that is traditional with Minolta Bodies will cause all kinds of grief. As I mentioned earlier, if the tension is wrong (and low batteries change the feedback from the servo/rewind motor) they will by default rewind.

Let us know what you find!

When my Konica Hexar starts rewinding the film in mid-roll its a sure sign that the batteries need to be changed.

Charles

[Outdoorsman]

[QUOTE=drg]First, the ISO DX encoding on your canisters contains three basic items:

1. ISO speed (i.e. 160, 800, 1600 etc.)
2. Number of exposures
3. Film Exposure Latitude. (how many stops of range for print film)

These cameras DO KNOW how long the film is and there are a few cameras that have overides and the ability to do stuff like advance to a particular frame (for mid roll rewind and reloading).
QUOTE]
Hmm... I've always been told that the film is rewound automatically when the camera senses tension. If the camera only rewound after a set # of frames, you could run into problems if the manufacturer screws up and gives you a short roll- this could mean grinding gears or even burned-up motors, I would think, when the camera keeps trying to advance and there's simply no more film... Not that this would happen often, if ever, but just in case.... or if the code gets haywire, you could end up wasting film or, again, have a camera thinking it's loaded with a 36-expsoure roll trying to advance past the available 24 frames and trashing its guts... or am I still wrong (as usual ;) )?
BTW, where can we find info on this stuff? How did you find this out? And is there any new info on the current standards for our own respective cameras? Do tell!

[drg]

[QUOTE=Outdoorsman]

First, the ISO DX encoding on your canisters contains three basic items:

1. ISO speed (i.e. 160, 800, 1600 etc.)
2. Number of exposures
3. Film Exposure Latitude. (how many stops of range for print film)

These cameras DO KNOW how long the film is and there are a few cameras that have overides and the ability to do stuff like advance to a particular frame (for mid roll rewind and reloading).
QUOTE]
Hmm... I've always been told that the film is rewound automatically when the camera senses tension. If the camera only rewound after a set # of frames, you could run into problems if the manufacturer screws up and gives you a short roll- this could mean grinding gears or even burned-up motors, I would think, when the camera keeps trying to advance and there's simply no more film... Not that this would happen often, if ever, but just in case.... or if the code gets haywire, you could end up wasting film or, again, have a camera thinking it's loaded with a 36-expsoure roll trying to advance past the available 24 frames and trashing its guts... or am I still wrong (as usual ;) )?
BTW, where can we find info on this stuff? How did you find this out? And is there any new info on the current standards for our own respective cameras? Do tell!

- - - - - - - - - -

The Camera Auto Sensing Codes (the Fancy name for DX numbering) was approved by ANSI in final form in late (August I believe) 1996 and was released in 1Q 1997.

Previous and virtually indistinguishable standards documents were around before that by several years. There is some history regarding weirdness in the industry that led to among other fiascos APS. This was part of overall an attempt to standardize and thereby produce better products in the consumer market worldwide. It did indeed drive a lot of sub standard film purveyors out of the general market and stores.

- - - - - - - - - - -

Please note, I said virtually all SLR's read the codes on the film. As far as I'm aware very few if any of the P/S (except the "posh") cameras are so enabled except for Speed. The standard for non-DX film (AGFA had some for a while as did Ferrantia(sp?) was to default to ISO 100. So the SLR cameras need an overide or if you want to push/pull film then theres some button or thing you scroll through a list of numbers to get the one you want.

As far as the exposure count I don't know of any 35mm SLR camera offering some degree of functionality beyond total manual control and has an auto film advance that doesn't at least read the number. The manuals for cameras '98, 99 and beyond that I've looked at including Magic Lantern guides all refer to something regarding exposure count. Some let you count down or up (remaing vs. exposed), one camera (and I don't recall which) winds the whole roll out of the canister and as it is exposed rolls it back.

They all have enough servo feedback control to accurately advance the film, that if the film jams or is at the end it stops advancing and tries to rewind. The last camera I had that actually ate a roll of film was a Nikon F3. Great camera though and it was probably just hot. Only happened once or twice with it as I recall. The old F2 with the motor drive got so it would occassionally just rip the film right out of the can, I always used a changing bag with it when the MD was in use.

So there are safeguards built in (particularly to the consumer oriented cameras) and one reason most don't have a higher fps capability as the motors and associated controls are a lot more expensive on the flagship units. The amount of sophistication in the modern AF SLR system camera is phenomenal compared to even 10+ years ago. They read the lens and some manufacturers of lenses do all kinds of funky stuff regarding flash and lighting (though you will be hard pressed to find out some of their secrets) and you can print data between exposure on the film and on and on.

The exposure latitude number is one I'd always wished more was done with. Nikon and Canon definitely and I also understand Contax used it as part of their metering system in conjunction with program/hyper shift so that rapidly changing light would not "let" the camera make a bad exposure. There never seemed to be a lot of documentation in English though I seen a couple manuals in Japanese that went in to great detail about the "featurism".
Of course this info only really applies to print film.

For some reason DX encoding wasn't very well explained to the general public other than, here it is, use it and .... A lot of this was explained in detail originally by the film reps to photographers and commercial suppliers and there were a few mag articles that is was coming, and then it was here and everybody went on. NBD.

I was working with documenting systems and saw a lot of schemes come and go including bulk reels for micro filming and ficheing holders that were physically keyed to press pins in cameras to indicate speed, exposure, and even material type (so the film base wasn't move to fast as that can cause problems). This was about the time the proposals for CAS was coming along 89 -90? maybe.

If you don't want to wade through the ANSI/ISO document jungle, look here:

http://www.geocities.com/thombell/dx.html

or just Google ISO DX Film (the link above was one of the first that came up) for more info.

Hope this is some help. If you want more let me know.

[another view]

I agree about first changing the batteries, and also checking the condition of the contacts but I'm confused on the film counter DX thing.

In the Nikon N8008s I used to have as well as the F100 and F5 I currently use, I can usually get 37 or 38 frames on a roll of 36. I would imagine that there's a good chance that those cameras would probably read all the DX info (but not sure), so why can I get more than 36 shots? I can set the F5 to stop at either 35 or 36 shots, but that's a camera setting (custom function). Didn't realize that DX was more than film speed!

[drg]

. . .. but I'm confused on the film counter DX thing.

In the Nikon N8008s I used to have as well as the F100 and F5 I currently use, I can usually get 37 or 38 frames on a roll of 36. I would imagine that there's a good chance that those cameras would probably read all the DX info (but not sure), so why can I get more than 36 shots? I can set the F5 to stop at either 35 or 36 shots, but that's a camera setting (custom function). Didn't realize that DX was more than film speed!

You can set the F5 to a manual setting that rewinds on feedback(tension) which it seems is the easiest to set, or the 35/36 setting. But what happens when you shoot shorts (12 exposure test rolls) or 24 exposures? Not having used an F5 for several years, how many contacts does it have in the film cartridge well? As I recall it had more than 4.


The F5 mayalso fall into that grey area of when it was manufactured regarding what it does with the info on the CAS panel. It's a mid-90's design and was released before CAS/DX was finalized I'm sure. The OCR/copy version of the Magic Lantern(copyright 1999) guide I looked at (somebody screwed up the page numbers) talks about revisions of firmware/update and off camera functions (see software note below).

I never owned an F5 but used one for awhile and as I remember the back panel display could show a number/code in addition to the film speed but it contained the speed? like 010032 or something like that with one of the the multitude of Custom functions. First 4 digits are speed, 5th digit is 0-3 (0-not specified, 1-12, 2-24, 3-36 exposure) 6 the digit was only active for print film or showed 0. Something like that. I'm sure I shot partial or short rolls a few times (knowing particularly what I used it for, I ran test strips I'm sure, but that been 7+years ago.)

I do know that Nikons in one form or another let you change to a Manual Mode for just about everything on their better cameras (as they should). The F5 was/is one of those cameras that was complicated enough and with the ability to download shooting data that there were various pieces of software (which may be where some of this gets specified) that did stuff that otherwise on the camera was very hard to do without the manual or the big cheat sheet.

As I mentioned earlier, the manuals from that period seemed lacking. Lots of talk about how well the Matrix Metering worked, when it worked (98% of the time or such). And why spend that amount on camera to use it in manual mode and not be able to use some of the older lenses without modifying the camera. Oh well. . .

Simple question, what happens if you load a 12 (short) or 24 exposure roll of film? The F100 I had just always rewound the film, and there was a setting but I can't find the manual or remember how it worked for the life of me. Still would use that camera except it sounded like a gun going off and no Mirror Lockup.

The Canon EOS-1,1n, 1v specify they rewind on 36, manual mode(no full frame advance detected and then rewind), or the DX code and thats been my experience with them. Its a pretty simple function with the options to leave the leader out etc.

[another view]

I've got a roll of film in the F5 right now but I'll have to look at that. The F100 does have six contacts and like you say it's possibly newer enough to take advantage of all of this (F5 in '96 and F100 in about '99).

Interesting that you mention the noise of the F100, I never noticed it until I went to the S2 digital (no film advance) and the F5 (different sound, a little quieter too). I don't have the Photo Secretary software but there's a lot you can do with it - not sure I need it though.

Thanks for the info!