reality check

[ann]

i read the following statement (elsewhere) and in over 60 years of photo education and work i have never heard or read anything like this statement.

was i out of the room when the fax was sent :rolleyes:



"See, it's not the film that the camera detects to determine film speed. It's that little black and silver box code (DX code) on the side of the cannister. The house brand ISO 400 film has cannisters with a ISO400 DX code on them. The house brand ISO 800 film has ISO 400 film in the cannisters marked with an ISO 800 DX code. The ISO 200 house brand film has ISO 400 film in the cannisters that are marked with ISO 200 DX codes.

See, some photographers mess with push/pull processing which means that they intentionally increase or decrease exposure for a given situation. And since film has this ability to be pushed and pulled they have made cannisters that fool your camera into thinking it has three ISO rating's to choose from, taking this forgiveness of film into consideration"

i am certainly willing to learn new things and in fact try something new everyday, but perhaps i best turn in my insturctor's badge if the above is true and i am clueless.

i am asking here , as there tend to be very few "bs fools" on this site with a high ratio of those who know what they are doing.

 

[donbga]

i read the following statement (elsewhere) and in over 60 years of photo education and work i have never heard or read anything like this statement.

was i out of the room when the fax was sent :rolleyes:



"See, it's not the film that the camera detects to determine film speed. It's that little black and silver box code (DX code) on the side of the cannister. The house brand ISO 400 film has cannisters with a ISO400 DX code on them. The house brand ISO 800 film has ISO 400 film in the cannisters marked with an ISO 800 DX code. The ISO 200 house brand film has ISO 400 film in the cannisters that are marked with ISO 200 DX codes.

See, some photographers mess with push/pull processing which means that they intentionally increase or decrease exposure for a given situation. And since film has this ability to be pushed and pulled they have made cannisters that fool your camera into thinking it has three ISO rating's to choose from, taking this forgiveness of film into consideration"

i am certainly willing to learn new things and in fact try something new everyday, but perhaps i best turn in my insturctor's badge if the above is true and i am clueless.

i am asking here , as there tend to be very few "bs fools" on this site with a high ratio of those who know what they are doing.

This maybe true Ann, especially with color negative films (that is color neg having a two stop latitude.) I think this maybe the result of some camera bodies not being made smart enough to read DX codes uniformly or properly.

I vaguely recall reading about this some where. It had no significance to me since I don't have cameras that read or use DX codes. My wife once had an Olympus Stylus that did that but we gave that to one of our nieces so I can't test for that condition now.

Don

 

[Jordan]

Ann -- DX-coding is certainly well-known -- I'm not sure there are any large commercial manufacturers who sell film without DX codes. Whether store-brand film is really all ISO 400 film loaded into 200-, 400- and 800-coded cartridges, I can't say.

 

[ann]

interesting, thanks don.

as i don't use color film nor use dx coded cameras.

so does that mean the "lab" does the correction for development, or with color does it make a difference?

 

[donbga]

interesting, thanks don.

as i don't use color film nor use dx coded cameras.

so does that mean the "lab" does the correction for development, or with color does it make a difference?

The wide latitude of modern color negative film made by Fuji and Kodak virtually assures over exposed negatives will be printable with acceptable quality, requiring only standard film development. Since virtually all of the processed films are printed by machine, computerized printers easily handle the density ranges of the negatives. Of course modern color paper plays a role as well.

Don

 

[ann]

jordan

i am well aware about dx coding, what i am not aware of would be the loading of the same film in different canister coded with a different iso than what the film was intended .
i over ride the coding as my EI is never the same as the box speed. I have tested all equipment to come arrive at my specific needs.

 

[jd callow]

Ann,
None of my cameras read the DX code. I don't know of any colour 400 iso film that won't be noticeably under exposed at an ei of 800 (most 400iso film pushed 1 stop would, in my world, equate to an EI of ~640 with 1 push in dev time), but then I test for my equipment and it must be that all of my meters and camera's are and always have been at least a stop off. Or at least that is what I am lead to believe by the experts found elsewhere.

 

[ann]

well, i am still amazed that a standard 400 film would be dx at what ever except 400. that is all i was trying to find out as i found the statement made by the quote i posted as very unusal. But as i am not a color person i thought perhaps i really was out of line thinking this is crazy.

 

[livemoa]

I find it hard to believe that a company would run the risk. To easy to check by standardised checking. Think of the opportunities for legal actions by consumers.

I do know photographers who use dx cameras and reuse film canisters for bulk loading and take advantage of the dx code to "fool" the dx system for plus or minus zone system stuff in 35 mm.

 

[Rick-in-LB]

If I remember correct, age showing here, when you look at the sprocket of the film it has the ISO printed there. I do not think that the companies would go and spend extra money to have this here if they were the same. But I don't know what big business thinks these days.

 

[ann]

rick,

that makes sense. perhaps i need (?) to buy a roll and have it developed and see what the rebate says.

 

[pellicle]

Ann

i read the following statement (elsewhere) and in over 60 years of photo education and work i have never heard or read anything like this statement.

...

"See, it's not the film that the camera detects to determine film speed. It's that little black and silver box code (DX code) on the side of the cannister.

still following to this point

The house brand ISO 400 film has cannisters with a ISO400 DX code on them. The house brand ISO 800 film has ISO 400 film in the cannisters marked with an ISO 800 DX code. The ISO 200 house brand film has ISO 400 film in the cannisters that are marked with ISO 200 DX codes.

See, some photographers mess with push/pull processing which means that they intentionally increase or decrease exposure for a given situation. And since film has this ability to be pushed and pulled they have made cannisters that fool your camera into thinking it has three ISO rating's to choose from, taking this forgiveness of film into consideration"

All cameras I've ever heard of have the ability to manually over-ride the DX code on the can. Packaging other than the right stuff in the can seems like its aimed at "an incredbile dummy" market. Still ... who am I to say. Perhaps some 'houses' (I'll assume training houses) have people whom they can't rely on to override that setting.


was that on target or did I miss the point in my reading comprehension?

 

[ann]

i understood the point about the dx coding on the cannisters and how that could be changed.

what i didn't (don't)understand is the idea the all the ISO are the same 400 film with just a different code with "changes" them to 800 , 1600, etc.

there are a few cameras on the market that will not allow one to override the code as they don't allow one to manual change the ISO; however, off the top of my head i can't be specific as to which ones. i want to say a nikon 80 but am not sure. From time to time i have a student who comes into a class with something that can't be manually changed.

 

[pellicle]

rick,

that makes sense. perhaps i need (?) to buy a roll and have it developed and see what the rebate says.

pop into the dark room pull out a few cm then develop that in a tray ... should save a 36 roll to remain useful as 30 or so exposures will remain

 

[ann]

true,

however, i rarely if ever use color film, but i suppose i could get a roll and then give the rest to a student.

 

[lxdude]

"See, it's not the film that the camera detects to determine film speed. It's that little black and silver box code (DX code) on the side of the cannister. The house brand ISO 400 film has cannisters with a ISO400 DX code on them. The house brand ISO 800 film has ISO 400 film in the cannisters marked with an ISO 800 DX code. The ISO 200 house brand film has ISO 400 film in the cannisters that are marked with ISO 200 DX codes.

See, some photographers mess with push/pull processing which means that they intentionally increase or decrease exposure for a given situation. And since film has this ability to be pushed and pulled they have made cannisters that fool your camera into thinking it has three ISO rating's to choose from, taking this forgiveness of film into consideration"

I cal Bull***t. Fraudulent behavior like that would open them up to legal action. The edge of the film would reveal the truth, unless the manufacturer went to the trouble to identify the film itself differently, which hardly seems worth it. Also, what house brand? What manufacturer? All of them, or just some, or just one?

Aside from that, though, this sounds like a case of a little knowledge being a dangerous thing. The writer cites push/pull processing instead of exposure latitude to "explain" the assertion. Push/pull processing is irrelevant. The writer uses the ability of film to be pushed or pulled as an example of film's "forgiveness", though that's only true with modified processing, which the (supposedly all the same) films won't be getting. Does this person think that films of different speeds require different processing? If that person knew what they were talking about they would have talked about exposure latitude, yet it's not mentioned. That makes me think they are full of it. That and the fact that any time someone repeatedly starts sentences with "see," my experience tells me they think they know more than they do.

I believe the origin of this is that many point and shoot cameras do not sense the full number of increments on the ISO scale, and rely on exposure latitude to cover for them. Instead of the full six contacts, some only have three, which let them read ISO 100, 200, 400 and 800. If you put in a 1600 speed film, it will read as 100. :eek:
Better ones, like my Pentax Zoom 90, have four contacts. That enables them to read from 25 to 3200, if their circuitry allows, but only in full stop increments, like 25, 50, 100, etc. Each number is used for the two next-higher speeds; i.e., 64 and 80 read as 50, 125 and 160 read as 100, etc.
I think this has gotten turned around in some people's minds as the film itself being labeled untruthfully.

 

[lxdude]

i understood the point about the dx coding on the cannisters and how that could be changed.

what i didn't (don't)understand is the idea the all the ISO are the same 400 film with just a different code with "changes" them to 800 , 1600, etc.

there are a few cameras on the market that will not allow one to override the code as they don't allow one to manual change the ISO; however, off the top of my head i can't be specific as to which ones. i want to say a nikon 80 but am not sure. From time to time i have a student who comes into a class with something that can't be manually changed.

A lot of consumer SLR's didn't allow ISO to be set. My Pentax P3n doesn't, and my old Nikon F401 (N4004) didn't either, IIRC. Stick on foil labels for cartridges are available to change ISO. Porter's camera store has them, I know. It's also possible to use tape and scrape off paint from the cartridge to modify it.
BTW, DX coding also tells the number of exposures. This enables the processing machine to know where the end of the roll is. Some cameras use the information to immediately advance to the end of the roll, then count backwards as the film is retracted into the cassette as the roll is used.
The DX coding also gives the exposure latitude of the film, which the processing machine uses during printing.

 

[ann]

lxdude,

the dx is not the point of this thread, it was a statement made by someone that i found unbelievable.

 

[lxdude]

lxdude,

the dx is not the point of this thread, it was a statement made by someone that i found unbelievable.

Sorry, just corroborating your statement regarding cameras without manual ISO setting, and throwing in info on how to fake them out. Again, sorry.

As stated in my first post, misunderstanding the limitations of some DX reading cameras may have been the origin of the thinking behind the statement, which I also find unbelievable.

 

[ann]

i understand, but i am still at a lost to find out the correctiness of the statement.

i talked to the folks at my local camera store (very responsible , knowledgeable folks) and they are as confused about that statement as i was. I thought perhaps i didn't get the fax

 

[lxdude]

Do you mean you're trying to verify if it's true or not? I have no idea where to find that information except to run tests. It's certainly the first I've heard of it, and the original statement states it as fact without backing it up.
I'm not surprised it's confusing to you or the camera store people. It's a confused statement.

The original statement, taken as a whole, indicates to me someone without much real knowledge. It just looks like another bogus statement based on incomplete knowledge and/or half-truths and/or faulty understanding and possibly the desire to claim devious behavior on somebody's part. It sounds good on its face, but I doubt it will stand up under scrutiny.

I think the fact you have never heard or read of it tells you just about everything.

If some company did label one film with different speeds to fool people into thinking they're getting something they're not, especially given that higher speed films usually cost more, it would be detestable. Also, IMO, legally actionable.

 

[ann]

yep, that is what i was trying to do. I thought it was outrageous to state something like that and frankly based on other comments from this person my feeling is they really have a poor background of knowledge.

it is amazing how much BS can be found these days.

Also, no one else called him on this bit of information, which i would have done, but wanted to do some research to be sure i had my facts correct.

thanks for taking the time to response to an older thread.