RonFrank
Contributor
Sorry if you found my remarks insulting.
Here is an explaination of ISO rating.
Using 200 speed film and rating it at 100 accomplishes two things. First it overexposes shots where there is enough light to provide the proper exposure at ISO 100. With negative film this results in oversaturation of the images, and is often done. The second thing it does is that in a situation where there is not enough light to provide good expsosure at ISO 100, it allows one to use the ISO 200 film latitude to capture images that would be underexposed using 100 speed film. As underexposing negative film is a very bad idea having ISO 200 film will provide 1 stop of additional underexposure latitude vs. just using ISO 100 film. As a long time shooter the original poster understands the benifit of rating ISO 200 film at ISO 100.
Push processing is very useful when one is in a situation where the fastest film in the bag is ISO 400, but is not able to shoot at ISO 400 due to subject, or equipment limitations based on the available lighting. A concert or nighttime sporting event would be common examples. In that case one rates the ISO 400 film at ISO 800 for example, and then has the lab push the process adding a stop to the development time to prevent a thin negative. There are certainly drawbacks to doing this, however it's not uncommon to shoot in this manner. Back in the day it was VERY common to rate ISO 800 film at ISO 1600 or even 3200 generally due to the film limitations at the time when shooting nightime pro sporting events. It was so common that Kodak developed and marketed their press film as pushable. The drawbacks of pushing film are increased grain, and contrast. However some do this for the effect even in situations where it is not necessary.
As the original poster did not bring up this option, nor did I suggest it, this may be off topic however it was suggested as something NOT to be done which I disagree with.
Here is an explaination of ISO rating.
Using 200 speed film and rating it at 100 accomplishes two things. First it overexposes shots where there is enough light to provide the proper exposure at ISO 100. With negative film this results in oversaturation of the images, and is often done. The second thing it does is that in a situation where there is not enough light to provide good expsosure at ISO 100, it allows one to use the ISO 200 film latitude to capture images that would be underexposed using 100 speed film. As underexposing negative film is a very bad idea having ISO 200 film will provide 1 stop of additional underexposure latitude vs. just using ISO 100 film. As a long time shooter the original poster understands the benifit of rating ISO 200 film at ISO 100.
Push processing is very useful when one is in a situation where the fastest film in the bag is ISO 400, but is not able to shoot at ISO 400 due to subject, or equipment limitations based on the available lighting. A concert or nighttime sporting event would be common examples. In that case one rates the ISO 400 film at ISO 800 for example, and then has the lab push the process adding a stop to the development time to prevent a thin negative. There are certainly drawbacks to doing this, however it's not uncommon to shoot in this manner. Back in the day it was VERY common to rate ISO 800 film at ISO 1600 or even 3200 generally due to the film limitations at the time when shooting nightime pro sporting events. It was so common that Kodak developed and marketed their press film as pushable. The drawbacks of pushing film are increased grain, and contrast. However some do this for the effect even in situations where it is not necessary.
As the original poster did not bring up this option, nor did I suggest it, this may be off topic however it was suggested as something NOT to be done which I disagree with.
