pushing C41 film -- contradictions

[jimdesu]

Hi there,

 

When I shoot B&W film (usually panF), I like to give a zone-III

pre-exposure, a 5-stop underexposure and a 5-stop push (well, I tell

*them* to give it the push, since I don't develop my own negs). I

like the results that I get from this, and was wondering if I could do

the same thing with C41 films. I searched around on the archive here,

and see two contradictory types of statements:

 

* You can push process C41 just fine, but expect color shifts

 

* You should never underexpose C41 film.

 

Which should I believe? Is it contextual and they're both right?

[anupam]

<i>I like to give a zone-III pre-exposure, a 5-stop underexposure and a 5-stop push</i>

<p>Can you post a sample of the results you get from this. Just intruiged.

<p>Thanks,

<br>-A

[steve_levine]

A color tri pack emulsion, and a silver based B&W film have very little in common in this regard. As you know with silver B&W films the box speed is simply a guideline, or a starting point. The developer, film speed ,time & temp combinations are limitless!

 

Color negative emulsions on the other hand, are best exposed at a single speed and developer combo. The only time these are pulled/pushed is when you seek some special effect. For example if you needed more speed, or wanted to increase contrast. All most all of the C41 push/pull questions here at PN are from people that have made meter/ISO setting errors.

 

Most labs that offer push/pull for color or B&W films usually only offer a 1 or 2 stop service. Asking them to push any film 5 stops is sure to raise their eyebrows.

[alan_olander1664878205]

You torture your film and then have someone else develop it? I can't imagine any decent results coming from this!!

[randrew1]

Puch processing (extending development) of any film will result in higher contrast, more fog, and maybe a little bit more speed. This depends on how you measure speed. If you look at the density of a grey card exposure, then you will see more "speed". If you look at the threshold speed in the deep shadows, then you wont see much increase in speed. A so-called push 2 development might yield a half stop in threshold speed increase. There are product to product differences, but what I've written in this paragraph holds in general for B&W, color neg, and color transparency film.

 

The problem with pushing color negative films is that the red, green, and blue layers don't all push at the same rate. The more you push, the more likely you will have mismatches between the three color records. Many slides films were designed for pushing and have reasonably matched red, green and blue response. Very few color negative films were designed for pushing. Some of the Fuji Press films and Kodak Ektapress films mentioned pushing, but most color neg films don't mention it and aren't particularly well matched when you push them.

 

I've met photojournalists who frequently pushed film by one, two, or sometimes three stops. While the deep shadows might not move along with the rest of the tone scale, they were getting something that they wanted from the extended development. My personal bias is to rely on under-exposure lattitude with normal processing rather than deal with the increased contrast I see with push processing.

 

The bottom line is try it and judge for yourself. (But I'll be surprised if you find anyone who will offer push 5 service on a color film.)

[rowland_mowrey]

James;

 

OTOH, what no one mentioned is that color negative films tend to have a lot of latitude without pushing. Therefore, they tolerate quite a bit of over and under exposure without the need to change the process at all.

 

See the thread here, keyword "armchair" and author "Dainis" for examples, and also my followup thread with additional examples.

 

Ron Mowrey

[James G. Dainis]

<a href=http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=008mLp> <U>Keyword "armchair" author "dainis"</U></A>

 

<P>I think the practical limit of developer would be a 2 stop push. The film could be in the developer for a day or two and I think there would not be any significant density increase of the highlights than that. So, you pre-expose to zone III, which gives the film a zone III wash, then you underexpose (say a gray card, zone V) by five stops. The gray card would still be on zone III due to the pre-exposure. Then you give an N+5 development. Again, I think that would only amount to about an N+2 (or maybe N+3). You may then just be raising the gray card back up to zone V (although I would suspect Zone IV. I haven't figured out yet what that would do to the shadows or highlights. Could you elucidate?

[jimdesu]

Well, I've never tried to explain it, but here goes.

 

Give the thing a zone-III pre-exposure, fogging at that level. Normally speaking, if you subtracted five stops, your Z-V exposure would land under Z-III and be lost, as would everything under zone VIII. When you pushed the film, your shadows & mid-tones would be horribly compressed, resulting in an ugly, thick negative. But, with the pre-exposure, it doesn't work this way. Because you're already (way) off of the toe on the H&D curve, all the light that hits the film makes *some* difference. Your highlights at zone VIII that would normally land at Z-III don't make a Z-III exposure, because it's already there! Instead, you end up with twice the amount of exposure, putting you up to Z-IV. All of your exposure is compressed into the range between zones III & IV. When you give the film a five-stop push, you blow out that exposure back up to the zone IX range. I meter specular highlights at zone VIII; if you wanted to keep them without risking blowing them out (for instance, if you were measuring a forehead highlight), you might give a four-stop push instead. What you end up with is a relatively thin, low-contrast negative, with a lot of mid-range tone, and little to speak of for shadows. At this point, I scan it and start playing around in Photoshop, adding contrast back where I want it.

 

I wish I had a picture to post, but I had to re-install windows, and don't have anything on disk anymore but some shots on Impressa. I really like Impressa (and have a small cache of it in the fridge), but wish I could shoot it at 1600 and get even less contrast with it, hence my post.

 

(o:

 

James

 

PS. I know it's asking someone to torture the film, but it means I don't have to keep a bunch of chemicals in the house. :)

[jimdesu]

P.P.S. I don't have anything to show as an example, but check out pictures online by William Mortensen to see the sort of look that it generates (I got the idea from him).

[rowland_mowrey]

The problem is, as stated above, that each layer develops at a different rate. In fact, each of the 9 or more emulsions in every color film develops at a different rate.

 

In all films, this is designed to come together at the proper development time and give identical curves, otherwise you can get crossover.

 

It does not need to happen, but it most often does. It is minimized in the "Press" films, or those designed for pushing.

 

This problem even happens to some extent in B&W films if you over or under develop them. After all, they are blends of 3 or more emulsions themselves.

 

I prefer just over or under exposure with normal process times. Sometimes I pull 160VC when I make internegatives, but thats about it.

 

Ron Mowrey

[scott_eaton]

<I><b>All most all of the C41 push/pull questions here at PN are from people that have made meter/ISO setting errors. </i></b><P>I disagree with Rowland on this one. He's being too kind and should substitute 'lawn-chair' with 'arm-chair'.<P>Uh, hey Steve, I'm shooting a wedding with my RB this weekend. Can you lend me some 1600 speed print film in 120 format?<P>This topic occasionally pops up, and what's such a riding joke about it is the biggest 'experts' on the topic woulnd't know what <i>frikken end</i> of a dip -n- dunk C-41 processor to load the film in.<P>I mean seriously,I used to drop close to a thousands rolls a week of nothing but professional C-41 film for clients, and yeah, we'd get a weirdo now and then who'd insist on pushing his VPS and Gold 100 a stop because of some article in Pop Photo. The resulting prints didn't look that great because of the shifting in the dye layers as described above and increased contrast, but it worked...I guess. <P>Then again we'd get lots of rolls of Kodak Ektapress 400/800, and Fuji NHG II (now NPZ) to push, and the results were much better because those films, as indicated on Fuji and Kodak's web sites, are *designed* to handle extended developer time with minimal dye shifting. So, why the heck should we listen to Steve and the other guy tell us "it ain't so" when those of us who've <b>actually worked</b> on professional C-41 lines know what can/can't be done?<P><I>Which should I believe? Is it contextual and they're both right? </i><P>Pushing C-41 film accomplishes the same thing as pushing conventional B/W film, excpet with C-41 film you're dealing indirectly with the dye coupler action. You basically increase middle/highlight density, and hopefully push those values far enough away from base d-min to get a decent looking scan/print. Same logic/same goal. Under exposed print film yields grainy, muddy prints without digital correction, but pushed C-41 film (assuming the film is a type designed for pushing) will hopefully yield at least better middle tonal values to work with vs mud, which is the whole idea. Nothin' fancy or contradictory about it.

[scott_eaton]

<I>P.P.S. I don't have anything to show as an example, but check out pictures online by</i><P>I don't have anything I can post due to copyright restrictions, but if I were to scan and post my NPZ shots processed normally, and shots pushed a full stop (I used to push a lot of 120 NPZ), you or nobody else here could tell the difference without squinting.

[rowland_mowrey]

Scott;

 

I really don't know what you are implying that I said, but when you read what you posted and compare it to my posts, you are really agreeing with me except for the last paragraph.

 

You say there that you are just dealing with dyes not silver, but you have left out the effects of diffusion and that of having 9 different emulsions. The diffusion rates through a film 9x thicker than most B&W films, the rates of development of 9 emulsions, and the coupling rate of at least 6 - 9 different couplers lead to huge variations in rate throughout a color film. This can be quite undesirable.

 

As we BOTH said, the press films have been designed to minimize this. Other films have not. Therefore pushing is 'iffy' for most any color film but less problematic for the press films.

 

I have done a lot of processing Scott, as well as film and paper design. I don't recommend pushing or pulling, but if necessary, one should stay within a stop of the rated speed.

 

Gee, it sounds as if we agree, but you still like to sound as if we disagree.

 

Ron Mowrey

[bernhard]

I don't know of any lab that would do a 5 stop push on C41 film, labs that will agree on pushing 3 stops are rare enough. So here's the practical end to that little exercise in "film torture".

[elliot_n]

'If I were to scan and post my NPZ shots processed normally, and shots pushed a full stop

(I used to push a lot of 120 NPZ), you or nobody else here could tell the difference without

squinting.'

 

I haven't tested NPZ, but I have tested all the Portra films, and a 1 stop push yields a

significantly different print from Normal processing with all of them.

[andrew_john_chapman]

You can push C41 no problem, the problem thesedays is finding a lab that does it.