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10-24-2008, 07:26 PM   #1
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Pushing film vs higher ISO

What's the difference, visually, between pushing a lower-rated film to, say, 400 ISO as opposed to simply buying a 400 film off the rack? I could understand how useful it could be if you could simply bump it up for one or two shots, but if you have to bang off a whole roll, why wouldn't you just get a higher-rated film? Is it about grain? Contrast? Is it like the difference between a right-handed wrist-spinner and a left-handed offie? (Aussies, Poms, Indians, S.Africans will understand...).

10-24-2008, 07:57 PM   #2
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QuoteOriginally posted by Wombat Quote
What's the difference, visually, between pushing a lower-rated film to, say, 400 ISO as opposed to simply buying a 400 film off the rack? I could understand how useful it could be if you could simply bump it up for one or two shots, but if you have to bang off a whole roll, why wouldn't you just get a higher-rated film? Is it about grain? Contrast? Is it like the difference between a right-handed wrist-spinner and a left-handed offie? (Aussies, Poms, Indians, S.Africans will understand...).
With one choice, you get a 400 ISO film, with the other, you get a high contrast low speed film, likely with more grain than the 400 speed film, but not much more speed than what the box says.
You'll do better with slide film, push processing actually kinda works with it.
10-24-2008, 10:31 PM   #3
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C-41 films are good for bumping it up a few shots - they've got a lot of of latitude.

There are many reasons Lithos pushes a slower film.

One, it's because there's never, ever enough light.

Two, because some of us like the visual results - the contrast, the shadows that are built like a brick...thunderbox, hell, the grain like the of wheatfields of Cana- the WA Wheatbelt.

Three, because some of us are poor and stuff like Delta 3200 or TMZ P3200 are twice as expensive as a roll of Tri-X. (Delta 3200 goes for $15.95 here. Professional slide films - like Provia 400X, go for about $24.)

It's more like getting Warnie to bowl fast on a slow pitch. Mightn't be technically correct, or proper, or accurate, but it sure is entertaining. Granted, watching Warnie having to bowl with a runup of more than ten feet after a night of booze, blondes, Bennies and baked beans would be even more entertaining.

With most films, especially black and white and film you dev yourself, it's hard to push faster than a stop - not because it's not possible, but because there's little info on it. Little point, really. And I can't really afford to blow two or three films finding out what times you need to push, say, an ISO 125 BW film three stops to ISO 500. It's a case of "Why don't you just buy a roll of ISO 400 film?"

Some films you don't have to worry to much about pushing. As mentioned, C-41 has practically limitless latitude, but still, it's better to pick the film closest to the speed you need.

In terms of most-to-least latitude, it goes roughly like this:

* C-41 films
* Cubic-grain BW films
* T-grain BW film
* Slide Film

Of the "dedicated" high-speed black-and-white films - Delta 3200, Neopan 1600, TMZ 3200 - none of those are really at their box speed. It's hard to find hard data on their true speeds, though the Film Developing Cookbook, lists TMZ 3200 at about 800-1000 ISO, Delta 3200 at 1000-1250 ISO, and Neopan 1600 at 650 ISO as their "realistic" speeds.

If you look on their boxes, they won't actually have an ISO rating (because in legal terms, the box speed isn't actually their ISO rating); instead they'll have an "EI" rating - this is what the manufacturer is telling you to expose at and dev at. EI stands for "Exposure Index" and means you're actually pushing the film anyway.
10-24-2008, 11:58 PM   #4
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lithos, your knowledge and love of film is awesome! always enjoy reading your posts

10-25-2008, 12:13 AM   #5
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Yeah, thanks for the lesson mate.
10-25-2008, 12:45 AM   #6
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QuoteOriginally posted by k100d Quote
lithos, your knowledge and love of film is awesome! always enjoy reading your posts
I was just about to say the same thing...

And nice example of Warnie, mate. I fully understand! The thought of that great arse wobbling in off a long run-up at the 'Gabba - jeez! Makes the eyes water.

So from what you and Wheatfield are saying you get more grunt, more contrast and grain, from a film that's pushed up to 400 ISO than a dedicated, out-of-the-box 400? When I got my ME-F a few days ago ('scuse me, I just wet myself with the joy and excitement of it...) I bought a couple of rolls of Ilford FP4 Plus B&W, 125 ISO. Just about finished the first roll and I was thinking of trying pushing it up a couple of stops, because I really love that deep black and heavy contrast look that you showed in a recent thread, Lithos. But you seem to be saying it's probably not worth more than one stop for B&W. So that would be 200, I guess. I might give it a go just for fun, then just experiment with other films.

Speaking of which, Wheatfield, have you tried Bluefire Police film, by any chance? I believe it's made in Canada. Came across it on the Frugal Photographer website and they describe it as medium speed ultra-high resolution, capable of heavy cropping. I'd be interested in your assessment if you've used it. And BTW, I notice a Rottie on your avatar. We had them for 18 years and just love 'em to bits. We're dogless at the moment, but if we ever got another, there's only one breed for us...

Thanks, guys. More stuff to have fun with - I want to live forever!

Cheers,
Les
10-25-2008, 01:37 AM   #7
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QuoteOriginally posted by Wombat Quote
I was just about to say the same thing...

And nice example of Warnie, mate. I fully understand! The thought of that great arse wobbling in off a long run-up at the 'Gabba - jeez! Makes the eyes water.

So from what you and Wheatfield are saying you get more grunt, more contrast and grain, from a film that's pushed up to 400 ISO than a dedicated, out-of-the-box 400? When I got my ME-F a few days ago ('scuse me, I just wet myself with the joy and excitement of it...) I bought a couple of rolls of Ilford FP4 Plus B&W, 125 ISO. Just about finished the first roll and I was thinking of trying pushing it up a couple of stops, because I really love that deep black and heavy contrast look that you showed in a recent thread, Lithos. But you seem to be saying it's probably not worth more than one stop for B&W. So that would be 200, I guess. I might give it a go just for fun, then just experiment with other films.

Speaking of which, Wheatfield, have you tried Bluefire Police film, by any chance? I believe it's made in Canada. Came across it on the Frugal Photographer website and they describe it as medium speed ultra-high resolution, capable of heavy cropping. I'd be interested in your assessment if you've used it. And BTW, I notice a Rottie on your avatar. We had them for 18 years and just love 'em to bits. We're dogless at the moment, but if we ever got another, there's only one breed for us...

Thanks, guys. More stuff to have fun with - I want to live forever!

Cheers,
Les
I'm not going to try to wade through the Aussie whatever the heck you guys call that but..

I haven't used the police film, probably won't. My film interest is 4x5 sheet, I've pretty much gone to digital for everything else.

C-41 film is a develop to completion process. This means that what the box says is pretty much all you will get out of it for speed.
B&W neg film is somewhat more responsive, but no more than a stop of speed increase, and that takes a heck of a lot of extra development.
Slide film (E-6 and Kodachrome) are both more responsive to pushing because of the nature of the process (reversal).

Note, this is a seperate parameter from the exposure latitude. Lithos is spot on with his assessment, though I think B&W tends to have more latitude than C-41, just because of the ability to vary developement. T-grain films are less resonsive to development changes than conventional grained films.

Many years ago, I ran a series of film tests which I posted to the net. I was primarily comparing granularity, and to a certain extent, resolution, though it was fairly subjective, as it was pretty much all visual measurement. One of the films I tested was the old Ektapress 800 film. It was the only C-41 film that responded at all to push processing, and it may have given up as much as a half stop of speed, and that would have been a "two stop" push (according to the Kodak data sheet)
I did extensive sensitometric testing with various black and white films when I was teaching myself the Zone System, and found essentially the same thing as I found with C-41 neg film.
You can alter the characteristic curve and if you have detail in the zone 3 range, it can be brought up to zone 4, but this is not altering the actual measured speed, and you are raising your higher zones much faster, which gives the soot and chalk effect common to over developed films. I did make sure I ran my tests as close to the ISO standard as I was able to.

If you like Rotties, you might like my book:

A Day at the Beach | Book Preview

or some fun pictures of dogs playing on a beach:

A Gallery of Fun

Or even my boy growing up:

Jester's Index Page

Jester is an incredible dog by anyone's standard. His background is mostly Schutzhund on his sire's side (most every dog going back to the early 1900s being either a Schutzhund I or III, and lots of working titles on his dam's side as well.

He is sort of like John Wayne with fur......
He's my third Rottie, and is one of the hardest dogs I have met.
My own training background is obedience and the protection part of Schutzhund, and Jester is hands down the best dog I've ever had the pleasure of training for bite work.
He has a rock solid temperament, loves people, is a bit iffy with other dogs (not surprising for a herding dog), and is completely fearless.
He is also the most affectionate dog I have ever met.

_IGP4153

He's just past 2 years now, and has two obedience titles and 3 points towards his championship. He has excellent hips and good elbows. He has excellent movement, and very good conformation, though I fear he may be a bit easty/westy, but we'll see when he his chest drops and he hits his full weight. Right now he tips the scales at around 47 kilos, with his present build, I expect him to weigh in at around 55-60 kilos when he is done growing. He's a big boy at ~68cm to the shoulder with lots of bone and a well sprung chest.

Last edited by Wheatfield; 10-25-2008 at 01:57 AM.
10-25-2008, 05:04 AM   #8
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QuoteOriginally posted by Wheatfield Quote
You can alter the characteristic curve and if you have detail in the zone 3 range, it can be brought up to zone 4, but this is not altering the actual measured speed, and you are raising your higher zones much faster, which gives the soot and chalk effect common to over developed films.
That's what I was wondering - so the speed actually stays the same but the sensitivity is raised, is that right? Sort of like, the film doesn't know it's been beefed up, but the camera does?
I think I need a Bex and a lie-down to digest all this. I'll still give it a go, though, but I might try HP4 or 5 next time (I'm a bit of an Ilford fan) to really get some crunchy grain.

Oh, those Rottie shots! I melt! Especially love the ones of the two chasing each other round the park bench in the snow. That Belgian shepherd is a handsome dog - I've never seen one. And it looks like Jester loves the water. Our last one was the same, you couldn't keep her out of it. What did you take those shots with - it's one helluva lens; so sharp and clean and contrasty. Great shots.

Thanks for all the info.

10-25-2008, 11:59 AM   #9
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QuoteOriginally posted by Wombat Quote
That's what I was wondering - so the speed actually stays the same but the sensitivity is raised, is that right? Sort of like, the film doesn't know it's been beefed up, but the camera does?
I think I need a Bex and a lie-down to digest all this. I'll still give it a go, though, but I might try HP4 or 5 next time (I'm a bit of an Ilford fan) to really get some crunchy grain.

Oh, those Rottie shots! I melt! Especially love the ones of the two chasing each other round the park bench in the snow. That Belgian shepherd is a handsome dog - I've never seen one. And it looks like Jester loves the water. Our last one was the same, you couldn't keep her out of it. What did you take those shots with - it's one helluva lens; so sharp and clean and contrasty. Great shots.

Thanks for all the info.
I'm going to be a bit of a pedant here.
Sensitivity and speed are the same thing, and that really doesn't change much with overdevelopment. If I had my charts at hand from when I was dialing in sheet film I could post graphs of what I mean.

What happens as we increase development time is that the dark areas (Zone I) don't move, or don't move much, but the brighter areas, where more silver is forming do move towards higher density, with areas of greater exposure moving towards greater density faster than areas of lesser exposure.

I grabbed a screen shot from the Ilford website, included below.
For the sake of discussion, presume that the black line represents normal development, and the turquoise line, which I added, represents more than normal development for this film.
The two lines start out at the same place, irregardless of development time, but the film receiving more development returns greater density from quite low on the exposure range (but not at the speed point) on up.
This is an increase in Gamma (contrast), but not speed (sensitivity).

Film speed is calculated from the amount of light/ development to give a film density of 1 stop over base density plus fog, and that density really doesn't move around much with overdevelopment.

My dog pictures were taken with a combination of the 70mm LTD or 77mm LTD (the backyard pictures) or various lenses, including an Espio 750 for the baby Rottie pictures. The ones on the beach were shot with either the Pentax K 105mm f/2.5 or an old Tokina SD 80-200 f/2.8, which has turned out to be a remarkable performer on the digital, and belies the myth that old glass isn't up to the task of imaging on a DLSR sensor.
I'm glad you liked the pictures.

Last edited by Wheatfield; 02-05-2011 at 08:44 PM.
10-25-2008, 05:27 PM   #10
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You weren't pedantic at all - it was a very clear explanation. I don't have your knowledge of the Zone system - only what I've learned from using Lightzone - but it really helps in understanding all this. I've thumbed through Ansell Adams' books in various bookshops, but they're very dense and go into more detail than I really want. There's plenty of websites, though, so I'll check them out. And I will read up some more about how film is actually constructed and what happens in the developing process. It's pretty interesting stuff.

Thanks again. Time to finish off that roll...
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