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Thread: Changing ISO of film

  1. #1
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    Default Changing ISO of film

    Hi,

    I am very new to the arcane art of changing the ISO of rated DX film...... I think it's called pushing and pulling film... whichever applies to which.......

    Ermm..... let's say that I am shooting in low light and using ISO400, then should I up the ISO number to make the film more sensitive to ambient light or drop it?

    Conversely if I use ISO400 and shoot in bright conditions, then how should I tweak my ISO settings??


    Some very noob questions:
    How much different is tweaking ISO settings and compensating via the camera?
    Why change the ISO anyway?
    Can I switch ISO numbers on a single roll halfway? Like I start of with ISO400 film, shoot like 10 shots then change it to ISO800? Can? What happens when I send to the lab and then dun know I changed the ISO rating of the film?


    Thanks a million in advance!

  2. #2

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    if u're shooting in low light with ISO400..u can either use flash, or push ur ISO to 800 or 1600. Pushing will result in faster shutter speeds, but as a result, ur pics will turn out grainer and not as detailed as when shot on e original speed (depends on how high u push).

    if u use ISO 400 in bright conditions n e meter says u're gonna overexpose....then increase the depth of field, or, put on a filter. Conversely, u can also pull ur film to ISO 200 or less. but then ur pics may turn out to be over contrasty.

    i guess ppl push/pull film to get effects as mentioned above and also, for more stable and appropriate shutter speeds.

    u haveta to let the developer know how many stops u pushed/pulled ur film..so that they can custom the developing time for ur film.

    u cant push/pull halfway thru a roll as far as i noe cos the entire roll will be sent for processing and developing. u will lose shots, depending on wat ISO u told the lab to develop at.

    hope this helps.

  3. #3

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    Hi,
    I am very new to the arcane art of changing the ISO of rated DX film...... I think it's called pushing and pulling film... whichever applies to which.......


    Merely changing the ISO and developing as normal is called rerating. Pushing and pulling involves changing the ISO and then informing the developer to compensate for the amount pushed/pulled.


    Ermm..... let's say that I am shooting in low light and using ISO400, then should I up the ISO number to make the film more sensitive to ambient light or drop it?
    Conversely if I use ISO400 and shoot in bright conditions, then how should I tweak my ISO settings??


    You change the ISO only if the film is not appropriate for use in that condition. For example if you are stuck with ISO100 film at night or you have ISO 800 film in daylight.

    If the exposure is sufficient or within normal parameters, there is no need to do anything.


    Some very noob questions:
    How much different is tweaking ISO settings and compensating via the camera?


    Changing ISO and EV compensation both achieve the same effect. The only thing is that changing the ISO is normally used for an entire roll, whereas EV compensation is more easily accessed and is used on a shot to shot basis. There's no stopping you from doing the reverse though.


    Why change the ISO anyway?


    1)When circumstances force you to do so.(no highspeed film in low light and no flash)
    2)When you prefer the results of exposure.(shootng ISO200 at ISO160 for more shadow detail)
    3)When your camera is known to consistently over/underexpose.(This is better resolved by sending it in for servicing.)


    Can I switch ISO numbers on a single roll halfway? Like I start of with ISO400 film, shoot like 10 shots then change it to ISO800? Can? What happens when I send to the lab and then dun know I changed the ISO rating of the film?
    Thanks a million in advance!


    Your latter shots will be 1 stop underexposed then. But usually this can easily be salvaged through print compensation.

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    Newbie here. Since this thread related to my doubt, I will ask my question here also. I loaded ISO200 film into my camera. I set the camera so that I wont detect DX setting of my film. The ISO setting in the camera is set to 3200.

    I shot about 10 shots, then I realized the ISO is wrong. I set the correct ISO to 200 in my camera. My question is, what happen to the 10 shots that I took using 3200ISO setting? is it underexpose? thanks

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    Quote Originally Posted by hanoman
    Newbie here. Since this thread related to my doubt, I will ask my question here also. I loaded ISO200 film into my camera. I set the camera so that I wont detect DX setting of my film. The ISO setting in the camera is set to 3200.

    I shot about 10 shots, then I realized the ISO is wrong. I set the correct ISO to 200 in my camera. My question is, what happen to the 10 shots that I took using 3200ISO setting? is it underexpose? thanks
    That depends on how you develop the roll.

    If it's develop at ISO 3600, then your laters shoots will be overexpose...

    If it is develop at ISO 200, then your first 10 shoots will be underexpose...

    Oh ya, it also depends on how much the film can be push pull.... Normally, you don't push/pull 4 stops on a film which is the case in your example.

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    Oh man! I think I will scrap the whole film and use a new one. I will happy shooting with the remaining film.

  7. #7

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    Those shot at ISO3200(4 stops under) are gone. Just continue with the rest of the roll at rated ISO.

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    Quote Originally Posted by hanoman
    Newbie here. Since this thread related to my doubt, I will ask my question here also. I loaded ISO200 film into my camera. I set the camera so that I wont detect DX setting of my film. The ISO setting in the camera is set to 3200.

    I shot about 10 shots, then I realized the ISO is wrong. I set the correct ISO to 200 in my camera. My question is, what happen to the 10 shots that I took using 3200ISO setting? is it underexpose? thanks


    Wah!! 4 stops under is like quite a lot leh!! Never tried rerating film before...

    Just to clarify my understanding:

    Let's say shooting in low light, and I have ISO 400 film, this means that the film speed requires a certain exposure time, and I want to shorten it. So I set the ISO at 800 instead, one stop down (or is it half?). This means now that the film will be exposed for a shorter time. So will this mean that the shots will look underexposed even when developed with due compensation by the lab?

    Cos I thought under low light, u want more light to enter the camera but u cannot afford the long shutter speeds, so u use faster film. But by pushing the ISO up for a slower film, u are in effect underexposing the shot right? Details will be lost?

    I'm rather confused......... when the lab compensates for what your changed, let's say from 400 to 800, does it mean now that they extend the development time? If so, then does it mean that it would be good to use ISO400, push i to ISO800 and develop it at ISO400 still. In this case, then wouldn't the photos look better?

    Am I making sense???

    I ask this because in another thread, Zerstorer told me that using ISO800 film is not advisable for elarging up to 8x12. This being the case, I will probably shoot on ISO400 film. But this means that the film may not be fast enough... and I might get rather long shutter speeds...... my concern is that the speed may dip below 1/30 sec... cos at 1/30 sec camera shake is only acceptable for my handholding...... my hand not very steady lar...... so the shots are not as sharp as they should be....... I'm rather hoping that with the flash I'll get 1/60, or 1/45. I might set to manual for 1/45 to capture more details....... so the other option is to change the ISO rating of the film.......

    Thanks a million for all who have replied thus far!! And hanoman u are welcome to use this thread to ask your own ISO questions........ I'm learning from what u asked as well!
    Last edited by TME; 30th September 2003 at 05:42 PM.

  9. #9

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    Quote Originally Posted by TME
    Just to clarify my understanding:

    Let's say shooting in low light, and I have ISO 400 film, this means that the film speed requires a certain exposure time, and I want to shorten it. So I set the ISO at 800 instead, one stop down (or is it half?). This means now that the film will be exposed for a shorter time. So will this mean that the shots will look underexposed even when developed with due compensation by the lab?
    Shooting ISO400 film at ISO800 will underexpose it by one stop. You can deal with it in 2 ways. Process as normal and compensate in the prints, or push-process(extend development time) 1 stop. For the first method, you will get the increased grain and duller colours typical of underexposed shots. The second way will result in more contrasty and perhaps slightly grainier shots but the main thing is that the negative will be darker and more correctly exposed.

    I ask this because in another thread, Zerstorer told me that using ISO800 film is not advisable for elarging up to 8x12. This being the case, I will probably shoot on ISO400 film. But this means that the film may not be fast enough... and I might get rather long shutter speeds...... my concern is that the speed may dip below 1/30 sec... cos at 1/30 sec camera shake is only acceptable for my handholding...... my hand not very steady lar...... so the shots are not as sharp as they should be....... I'm rather hoping that with the flash I'll get 1/60, or 1/45. I might set to manual for 1/45 to capture more details....... so the other option is to change the ISO rating of the film.......
    Note that you will be shooting with flash, when you are using flash, the shutter speed hardly matters. You can use the same shutter speed with ISO400 film as you do with ISO800 film. The only difference would be the effect of the ambient light in the shots, the net flash exposure will still be the same. This means that your subjects will be correctly exposed no matter what shutter speed you use, only the background light will be affected. In any case a 1 stop difference isn't much of a difference in real terms.

    ISO 800 film might allow you to capture ambient light shots, but those will be few and far between since you are covering the table shots. Whether
    ISO800 is acceptable for you for S8R depends on your tastes.

  10. #10
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    Quote Originally Posted by Zerstorer
    Shooting ISO400 film at ISO800 will underexpose it by one stop. You can deal with it in 2 ways. Process as normal and compensate in the prints, or push-process(extend development time) 1 stop. For the first method, you will get the increased grain and duller colours typical of underexposed shots. The second way will result in more contrasty and perhaps slightly grainier shots but the main thing is that the negative will be darker and more correctly exposed.


    Note that you will be shooting with flash, when you are using flash, the shutter speed hardly matters. You can use the same shutter speed with ISO400 film as you do with ISO800 film. The only difference would be the effect of the ambient light in the shots, the net flash exposure will still be the same. This means that your subjects will be correctly exposed no matter what shutter speed you use, only the background light will be affected. In any case a 1 stop difference isn't much of a difference in real terms.

    ISO 800 film might allow you to capture ambient light shots, but those will be few and far between since you are covering the table shots. Whether
    ISO800 is acceptable for you for S8R depends on your tastes.

    OOooo........... I see the light......... kekeke........ thanks a lot!!!

    I prefer very fine grain prints....... so I guess I will dispense with pushing the film.....

    As for ISO800...... haiz...... then I must take a look at an 8R enlargement of a shot under low light to decide.......

    With regard to the shutter speed and film speed thing...... do I understand u correctly that the shutter speed can be kept the same, but the flash duration and/or the film speed will compensate for the amount of light required to get the same exposure?

    Sorry but another question: If I am using ISO400 and on A priority at f/5.6 + flash. If metering the scene gives me 1/60 sec, I could slow down the shutter to 1/45 or 1/30 sec to capture more ambient light right? Then this gives me both a correct subject exposure and the ambient lighting that I am seeking? Is this correct??

    Thank you Zerstorer for being so patient.......

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    Quote Originally Posted by TME
    Sorry but another question: If I am using ISO400 and on A priority at f/5.6 + flash. If metering the scene gives me 1/60 sec, I could slow down the shutter to 1/45 or 1/30 sec to capture more ambient light right? Then this gives me both a correct subject exposure and the ambient lighting that I am seeking? Is this correct??
    i'm guessing you would be switching to full manual mode to adjust the shutter speed with the originally intended aperture used for metering in A-priority? this is not advisable as it will result in an overexposed shot, after all not only is the subject being lit by the flash, it is also being illuminated by the ambient lighting, thus the overexposure.

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    Quote Originally Posted by wacko
    i'm guessing you would be switching to full manual mode to adjust the shutter speed with the originally intended aperture used for metering in A-priority? this is not advisable as it will result in an overexposed shot, after all not only is the subject being lit by the flash, it is also being illuminated by the ambient lighting, thus the overexposure.
    Yes, of course must switch over to full manual. But will the overexposure be significant. We are talking of low lighting conditions in the first place, meaning to say that the ambient light is insufficient in the first place to light the subject properly. The flash is then used to light up the subject properly while the camera meters the exposure for the background. In which case, if the shutter speed drops, the ambient exposure will increase so that more ambient light is captured but the flash power remains the same so the subject remains exposed as without any exposure compensation. The relative increase in ambient light is minimal I guess in this case since it is already considered low light conditions...... so the effect on the subject is not very sigificant or cannot be seen in prints from negatives at least lar........ for slides I think the slides will wash out even with 1/2 stop overexposure........

    Err.. correct or not my reasoning?? I still very newbie to this..... but this is what I have unerstood (righly or wrongly) from the ongoing discussion in this thread.

    Thanks wacko for raising this issue.. look forward to your reply......

  13. #13

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    Quote Originally Posted by TME
    Sorry but another question: If I am using ISO400 and on A priority at f/5.6 + flash. If metering the scene gives me 1/60 sec, I could slow down the shutter to 1/45 or 1/30 sec to capture more ambient light right? Then this gives me both a correct subject exposure and the ambient lighting that I am seeking? Is this correct??
    Yes. This is what I do everytime. However, becareful of going below 1/45 if the subjects are not perfectly still as the ambient light may cause blurring.

    Quote Originally Posted by wacko
    i'm guessing you would be switching to full manual mode to adjust the shutter speed with the originally intended aperture used for metering in A-priority? this is not advisable as it will result in an overexposed shot, after all not only is the subject being lit by the flash, it is also being illuminated by the ambient lighting, thus the overexposure.
    As long as one is using either an Automatic or a TTL flash overexposure will not occur.

    Flash durations are typically shorter than 1/10000 of a second as such, any shutter speed you use below that doesn't affect the flash exposure at all, but only affects the ambient light you can capture.

    For auto/TTL flash, the flash is cut the moment the sensor detects sufficient exposure, there is no chance of overexposure regardless of the shutter speed you use, afterall this is how the principle of slow sync flash works.

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    does TTL still function in full manual mode? just wondering, cos i don't have much experience with that combination. i know on my rather old DC, the flash fires in full power (default) when in M mode, no E-TTL, not sure if newer cams are different.
    Last edited by wacko; 1st October 2003 at 05:12 PM.

  15. #15

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    Quote Originally Posted by wacko
    does TTL still function in full manual mode? just wondering, cos i don't have much experience with that combination.
    Yes it does. Unless you switch the flash mode to manual.

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    Quote Originally Posted by TME
    As for ISO800...... haiz...... then I must take a look at an 8R enlargement of a shot under low light to decide.......
    Well, I shoot with ISO 800 films and enlarge it before. Not very grainie to me... But then again, I was using Fuji Press 800... If you want, maybe I can bring down that 8RC print for you to see during the upcoming SEED...

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    Cool!! Now I know what sort of conditions and camera settings to expect..... so I won't be agonising then if the shots will turn out or not........ can spend all my energy on composing interesting shots..... like what JOho did.... he did a lovely job on his friend's wedding..... if only I had a DSLR...... can shoot like siaoz.... anything I want and also guarantee that I get good shots cos can preview and erase if I dun get it the first time around........

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    Quote Originally Posted by Kira
    Well, I shoot with ISO 800 films and enlarge it before. Not very grainie to me... But then again, I was using Fuji Press 800... If you want, maybe I can bring down that 8RC print for you to see during the upcoming SEED...

    Paiseh..... when is the SEED? Haven't been to one yet...... trying to get as economical as possible film..... Superia 400 is only $3.30 while the 800 is like $6.80...... so that's still okay by me...... but I guess Press 800 is going to cost a lot more...... can post the price here and availability? Thanks!

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    Quote Originally Posted by TME
    Sorry but another question: If I am using ISO400 and on A priority at f/5.6 + flash. If metering the scene gives me 1/60 sec, I could slow down the shutter to 1/45 or 1/30 sec to capture more ambient light right? Then this gives me both a correct subject exposure and the ambient lighting that I am seeking? Is this correct??
    Isn't this called slow sync? I know my camera can do this even when in aperature priority mode.....

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    Quote Originally Posted by TME
    Paiseh..... when is the SEED? Haven't been to one yet...... trying to get as economical as possible film..... Superia 400 is only $3.30 while the 800 is like $6.80...... so that's still okay by me...... but I guess Press 800 is going to cost a lot more...... can post the price here and availability? Thanks!
    If I'm not wrong, Press 800 is only around $7++ the last time I check....

    SEED is next wed at Peninsula Plaza food court...

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