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04-05-2009, 07:31 PM   #1
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ISO Curiosity

I bought some Fuji 800 ISO X-Tra which I have yet to try out. I got to thinking about switching ISO on the fly. If I loaded the 800 ISO film, took a few shots inside, then went out side in bright sunny weather and manually adjusted to 100 ISO on the camera what would happen? Being new to film I'm not sure if this would make any difference or not and thought I'd asked the more experienced.

04-05-2009, 07:35 PM   #2
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Your film is labeled as 800 speed right?

Resetting your ISO speed on the camera to 100 will have the effect of overexposing your shot by 3 stops.
04-05-2009, 07:56 PM   #3
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Umm, yeah, film does not change sensitivity when you adjust the ISO setting on the camera.
04-05-2009, 08:06 PM   #4
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negative film can take a lot of overexposure, but 3 stops is a bit much ... you start blowing highlights and get a soft look.

04-05-2009, 08:07 PM   #5
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QuoteOriginally posted by harfooz Quote
Your film is labeled as 800 speed right?

Resetting your ISO speed on the camera to 100 will have the effect of overexposing your shot by 3 stops.
hello,

I am even newer to film as I have yet to receive my first film camera and shoot the first roll
Would it be correct that for color negative film the ASA/ISO indicated value is usually overrated and it would make sense to setup ASA on the camera to a lower value to help prevent under-exposure.
i.e. I have just ordered some Ektar 100, should I dial in ASA 80 or 50?

Is that also true for B&W film i.e. Ilford Pan F 50 or FP4 125?

Thank you.

Luc


BTW ajuett we are both from Burnaby and sometime shooting in the same location (North shore in your web page and mine) :-)
04-05-2009, 08:25 PM   #6
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QuoteOriginally posted by lbenac Quote
hello,

I am even newer to film as I have yet to receive my first film camera and shoot the first roll
Would it be correct that for color negative film the ASA/ISO indicated value is usually overrated and it would make sense to setup ASA on the camera to a lower value to help prevent under-exposure.
i.e. I have just ordered some Ektar 100, should I dial in ASA 80 or 50?

Is that also true for B&W film i.e. Ilford Pan F 50 or FP4 125?

Thank you.

Luc


BTW ajuett we are both from Burnaby and sometime shooting in the same location (North shore in your web page and mine) :-)
Set it for the film rating unless you purposely want to pull the film.
04-05-2009, 08:26 PM   #7
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I realize that film ISO speed is, for lack of a better term, 'hard coded'. All I want to find out was what would happen if the ISO was changed on the camera. Thanks for the answers.
04-05-2009, 08:52 PM   #8
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Changing the ISO setting on the light meter, is the same as exposure compensation.

Have a look at the Exp Comp dial on your SuperProgram. The ISO setting and the Exp Comp are linked together.

04-05-2009, 09:05 PM   #9
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QuoteOriginally posted by KungPOW Quote
Changing the ISO setting on the light meter, is the same as exposure compensation.

Have a look at the Exp Comp dial on your SuperProgram. The ISO setting and the Exp Comp are linked together.
Thanks KungPow, I've played a bit with the exposure dial, very helpful at times. This was just about 'hard setting' the camera's ISO and what it would do to the photo. Regardless, thanks for the info.
04-05-2009, 09:29 PM   #10
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This is one variable I'm happy not to have with film.
Second is WB...
04-05-2009, 11:32 PM   #11
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@octavmandru - White balance is still an issue with film. Shooting under fluorescent lighting in highschool is the reason I learned how to use a flash. Depending on your shooting conditions coloured filters can be awfully handy too or you wind up trying to correct for colour cast when you're printing. As for ISO adjustment on the fly with film, that's where shooting with 2 or more cameras loaded with different film speeds comes in.
04-06-2009, 03:05 AM   #12
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QuoteOriginally posted by lbenac Quote
Would it be correct that for color negative film the ASA/ISO indicated value is usually overrated and it would make sense to setup ASA on the camera to a lower value to help prevent under-exposure.
i.e. I have just ordered some Ektar 100, should I dial in ASA 80 or 50?

Is that also true for B&W film i.e. Ilford Pan F 50 or FP4 125?

Thank you.

Luc
Luc, the best way is to start with the ASA speed the manufacturer has set. Then, depending on the results you get with your camera and the outfit you use to get the film developed and scanned, you may wish to adjust slightly.


Film responds to light in a somewhat non linear curve. The rated ASA represents a compromise between grain, latitude, etc. There are other compromises possible. Sometimes the compromise is influenced by marketing

For example, urban legend has it that one of the C41 B&W films (Kodak BW400CN or Ilford XP2) is actually 'ASA 320' but is rated at 400 due to marketing. HA! Perhaps that 1/3 stop consistently applied... but to what? What is someone actually metering? But it does seem true - these films have greater latitude towards over than under. And on the under direction, very quickly they get into grain hell.


Ektar, I've only shot one roll so far, and that was with a camera whose meter tends to over expose a bit, or bias the shadows. Using Ektar on that camera I'd be tempted to rate Ektar at maybe 1 or 2 ASA-steps over 100.

However, this adjustment for me would be camera specific, that is, unless I see the same trend across several cameras.
04-06-2009, 04:24 AM   #13
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QuoteOriginally posted by ajuett Quote
Thanks KungPow, I've played a bit with the exposure dial, very helpful at times. This was just about 'hard setting' the camera's ISO and what it would do to the photo. Regardless, thanks for the info.
It's good that you're thinking of using the ISO as exposure compensation -- it'll come in handy when you find a good bargain on a camera that doesn't have an exposure compensation dial . Those cameras tend to go for less money, and can be excellent values.

One of my favorite bodies for keeping in my bike's tank bag is an old MG. It doesn't have an exposure compensation dial. So I fake it by changing the film speed dial.
04-06-2009, 06:32 AM   #14
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I have always set Velvia at ISO 40 instead of the ISO 50 marked on the cassette since I feel I get a better result that way. But that is color slide film and not BnW that is far more sensitive to light at ISO 800, but changing ISO 800 to ISO 100 seems to me to be way to much.

Tom
04-06-2009, 06:56 AM   #15
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QuoteOriginally posted by Nesster Quote
Luc, the best way is to start with the ASA speed the manufacturer has set. Then, depending on the results you get with your camera and the outfit you use to get the film developed and scanned, you may wish to adjust slightly.


Film responds to light in a somewhat non linear curve. The rated ASA represents a compromise between grain, latitude, etc. There are other compromises possible. Sometimes the compromise is influenced by marketing

For example, urban legend has it that one of the C41 B&W films (Kodak BW400CN or Ilford XP2) is actually 'ASA 320' but is rated at 400 due to marketing. HA! Perhaps that 1/3 stop consistently applied... but to what? What is someone actually metering? But it does seem true - these films have greater latitude towards over than under. And on the under direction, very quickly they get into grain hell.


Ektar, I've only shot one roll so far, and that was with a camera whose meter tends to over expose a bit, or bias the shadows. Using Ektar on that camera I'd be tempted to rate Ektar at maybe 1 or 2 ASA-steps over 100.

However, this adjustment for me would be camera specific, that is, unless I see the same trend across several cameras.
It makes sense.

Cheers,

Luc
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