Canon 650 read the film speed wrong, or did it?

[brian_m.1]

I loaded a roll of 200 ASA Fuj film and the camera read it as ASA 320. I have had this camera since new and it has never got the film speed wrong. I am wondering if it's not the film itself. I can reset the film speed manually but not sure I have too.  Anyone seen anything like it?

[Ken Katz]

I never had this happen but always checked the ASA set by the camera before using.  It it possible for the camera to misread the ASA, so I would definitely set it manually.  EOS 650 is quite old or there may be some dirt or corrosion on the sensor in the film compartment.

[gordon_yee]

The DX codes for ASA 200 and 320 differ by one digit. Try cleaning the contacts in the camera's film chamber. Also clean the DX coding contacts on the film canister to remove any debris.

Film DX Coding – A photographer’s life hack - Photo Thinking - Technique

[brian_m.1]

Would I be off too much if I leave things as they are? How many stops?

[AJG]

46 minutes ago, brian_m.1 said:

Would I be off too much if I leave things as they are? How many stops?

2/3 of a stop underexposed should be the result.  You could probably set exposure compensation to overexpose to compensate or just avoid shooting with slide film which is more fussy about exposure.

[Ken Katz]

As AJG answered, 2/3 of a stop underexposed.  For shooting color print film it would not be a significant issue, but I prefer not to underexpose that type of film. Color print film has a whole lot of latitude for overexposure but far less tolerance for underexposure.   2/3 of a stop under is more likely an issue with color slides.  Seems the easiest solution is just change the ASA setting manually and check it each time you load film.  Cleaning the contacts on both the film cannister and camera would also make sense before you load another roll.

Edited January 9, 2023 by Ken Katz

[rodeo_joe1]

DX coding usually relies on the cassette being conductive or reflective. So dirt on the cassette or camera contacts/sensors can easily give a wrong reading. 

Most cameras allow for a manual override of the DX coding, since some cassettes don't have a code. Just set the correct ISO manually - it's a trivial issue. 

[BeBu Lamar]

Replace the film and see. One of the patch is conductive when it's supposed not. So it's not dirty but perhaps some of the paint is lost. 

[John Seaman]

If it still doesn't work I would tape over the contacts on the cassette and set the ISO manually.

 

[Tony Parsons]

Was this just on the one film, or is it a persistent error ? 

[brian_m.1]

Greetings!

Now that I have the said roll back, I thought you might be interested in what happened. Nothing! Exposures came out perfect. As AJG mentioned, the 2/3 stop was not enough to make a difference. I have attached a few shots. Don't remember if I used flash or not. Might have. What do you think? BTW, wiped down the contacts, loaded a roll of 400 Kodak Gold and it read it just fine. Oh, what happened to Modern Film Cameras? 

[glen_h]

You should be able to tell from the look of the negatives.

Well, with the low gamma of color negatives, it isn't so easy. 

In any case, they are supposed to do well with one stop under, up to two or three stops over, exposure.

It might be that the shadow of the dog is the wrong color, but then again,

I don't know what color it is supposed to be.

[brian_m.1]

Whatever ASA the camera read, the dog still came out cute, and that's what is important!