Pushing ISO

[Guest NEIL-D-WILLIAMS]

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So I have a new roll of Tmax400 and going to shoot at night..... pub kind of shots.

Should I just set my ISO on the Leica M6 to 800 and shoot away or leave it at 400 and add 1 stop of shutter speed each time I take a picture???

Thanks

 

Neil

 

 

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[andybarton]

Set the ISO on the meter to 800

 

Don't forget to adjust the development time to compensate.

[Guest NEIL-D-WILLIAMS]

Adjust development time say for 800 ISO too??

 

 

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[andybarton]

Yes.

[Guest NEIL-D-WILLIAMS]

Cheers mate

 

 

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[andybarton]

Let this be your guide... a really good starting point until you work out your own sweet spot. A great iPhone App available too

 

Every film and every developer at all sorts of ISOs. Pushed, pulled or straight down the middle

 

http://www.digitaltruth.com/devchart.php?Film=TMax+400&Developer=HC-110&mdc=Search&TempUnits=C

[Sergius]

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I think Tmax pushed to 800 has same development time of 400.

[semi-ambivalent]

Let this be your guide... a really good starting point until you work out your own sweet spot. A great iPhone App available too

 

Every film and every developer at all sorts of ISOs. Pushed, pulled or straight down the middle

 

http://www.digitaltruth.com/devchart.php?Film=TMax+400&Developer=HC-110&mdc=Search&TempUnits=C

And don't forget www.filmdev.org

 

s-a

[mikemgb]

Let this be your guide... a really good starting point until you work out your own sweet spot. A great iPhone App available too

 

Every film and every developer at all sorts of ISOs. Pushed, pulled or straight down the middle

 

http://www.digitaltruth.com/devchart.php?Film=TMax+400&Developer=HC-110&mdc=Search&TempUnits=C

 

I have this app, it is amazing, you want to know how to cross process XP2 in Ilfosol-3? It has that information.

[Chuck Albertson]

I think Tmax pushed to 800 has same development time of 400.

That's Kodak's recommendation. Try it and see if it works for your pictures, if not add a couple minutes to the ISO 400 development time.

[AlanG]

If you don't alter development how can you possibly be "pushing" the film by setting it to 800 ISO? You are simply underexposing by a stop according to your meetering. You then try to get a "good" image by compensating for the underexposure during the printing or scanning process.  ISO is a technical specification that represents a specific D log E curve and I don't think a film can't have two of them for two different ISO numbers no matter how you process it.

 

By the way, when you push film you no longer have an ISO characteristic curve but have an Exposure Index (EI) instead because it no longer meets the required curve shape.  That shouldn't stop you from pushing film and if you like the look you get from a given approach, it works for you.

[EoinC]

In agreement with Alan, changes during shooting are under- or over-exposing the film. The pushing and pulling is in the developing of the film.

[adan]

As a rule of thumb, pushed development should be about 1.4x the time in the developer per stop of underexposure (doubling of the ISO) - funny how the square-root-of-2 keeps showing up in photography.

 

E.G.

Normal dev. time for normal ISO 400 = 5 mins.

Expose at 800, develop for 7 minutes

Expose at 1600, develop for 10 minutes

Expose at 3200, develop for 14 minutes, etc. etc.

 

Now, the deal with underexposing is that you will lose shadow detail no matter how you develop. You don't get a "real" increase in film speed (i.e. shadow detail) because the silver in film requires a basic minimum "trigger" exposure to react at all. Strongly compensating developers or techniques (e.g. Diafine) can squeeze out every last silver grain, and gain you perhaps a quarter or half stop ISO gain over general-purpose developers (D-76, etc.) As measured by shadow detail. But that's it.

 

However, pushing with extra time will get the OVERALL or average density of the negative up to something usable: thin or non-existent shadow detail, "normal" density in the midtones, overly-dense or "blocked" highlights. The classic, contrasty "charcoal-and-chalk" look of push-processed film.

 

http://static.ofriwolfus.com/gallery/001.jpg

 

That may be why Kodak "allows" you to simply develop as normal for a small 1-stop underexposure (400 at 800) - the shadow detail is lost forever the moment you underexpose either way, but normal development will keep the highlights from overdeveloping and blocking (and getting very grainy). Plus it allows you to cheat one or a few shots on an otherwise normally-exposed roll, without overcooking the normally-exposed pictures.

 

As to the original question: Unless you have a tripod, choose your aperture and shutter speed to avoid motion blur, then meter to figure out what ISO is needed to achieve those camera settings (800, 3200, 6400). And use those settings, and give appropriate extra development. What you get is what you get.

 

One of Robert Heinlein's favorite words applies throughout photography - "TANSTAAFL" ("There ain't no such thing as a free lunch.")