What actually happens when you push film?

[Ruhayat]

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Hi.

 

I'm new to film pushing and pulling. But pushing sounds like a great way to get cheap fast B&W film to me. So I've been doing it more regularly these days, especially in low light. My two faves are Neopan 400 pushed to 800, and Lucky B&W (Chinese film) 100 pushed to 400. I have also tried pushing Tri-X 400 to 800, but the results were not as satisfying to my eyes as Neopan 400.

 

My question though is:

With pushed Neopan 400, I notice every now and then a couple of frames in a roll would have a greyish tone overall rather than the expected more solid black and white. It's almost like the picture is made up of grey haze. What's happened here?

 

Sorry I can't upload samples since I don't have a scanner, and the scanner my printer uses is not worth bothering with. I'll try and look for samples online and show you what I mean. In the meantime, has anyone come across a similar issue and know what I'm talking about?

[Ruhayat]

I guess in a way I'm asking, are there any special considerations one needs to take when using pushed (or pulled) film? Like, do you need to adjust to compensate for exposure or treat it differently than you would if you were shooting the film at the rated speed? I've been treating the pushed film as if natively it's at that speed. Eg, if I shoot Neopan 400 at 800 I treat it as if I'm shooting a roll of real Neopan 800.

 

Any advice with regards to handling pushed/pulled film would be most welcome.

[ndjambrose]

You treat pushed film exactly as you would if it were the stated box speed. You make it effectively that speed by your choice of development - no other compensation needed.

 

Couple of things though:

 

A one stop push isn't going to show you much. B+W film has a wide exposure latitude and a one stop push might easily be equivalent to a one stop exposure error. In other words, not really dramatic enough to see anything remarkable. You could probably get the same image by just developing at box speed.

 

Tri-X performs well in the range 1250 - 1600. If you're going to the effort of using extended development times you might as well make it worth your while and take it a little further.

 

Results are impacted greatly by your choice of developer. Some are better than others for a specific film stock. It's useful to experiment and see what you prefer. For example, I prefer HC-110 for Tri-X - lovely contrast and wide tonal range, but I've also tried XTOL and TMAX developers, and they all produce a slightly different result.

 

You can push film even further - as far as four stops - by using two bath development, where the film is processed in two different developer solutions, one for highlights, one for shadows. This gives a more even overall development at higher speeds, with less aggressive contrast. Diafine is a particularly suitable two bath developer.

 

There's less scope with pulling film, as it's harder to compensate for the exposure you made on film that was already receptive to light at a given EI. As a general guide, you can pull one stop and push three or four.

 

Finally, not all films are equally suitable for push or pull development. Some emulsions can go further than others.

 

Can't comment on your gray frame without seeing an example. It could be any one of a number of things.

[Ruhayat]

Wow. Thanks for that. Must try Tri-X at 1600, then. And also, for now I'm having my film processed by a fairly reliable shop -- found them after a couple of trial and errors with others. But I've already enrolled for a B&W processing course... can't wait.

 

Oh, and may I say that I've also been a great fan of your work for a while now. Excellent stuff! The Sugababes set is one that I particularly keep returning to for inspiration everytime I'm invited to go on location for friends' music videos. Never could get a similar mood and "feel", though. I still suck at composition when using a rangefinder, for some reason.

[sjt1]

OK here's my attempt at explaining pushing.

 

When you push a film, you deliberately underexpose it - i.e. if the meter says 1/30 at f/2 at ISO 400, and you want to push to ISO 800, you expose at 1/60 at f/2. This obviously causes less light to reach the film. The areas that receive least light are the dark parts of the picture (again obviously).

 

When you develop, you compensate for the underexposure by increasing development (e.g by increasing time or temperature). This has the effect of increasing contrast, because the areas that received adequate exposure will be increased in density on the developed negative, but in the dark parts there will not be enough exposure to make much difference. If you do not increase development you will likely get a flat (low contrast) negative, and if you increase too much you will get a very contrasy negative - this is because the highlights have lots of density but still the shadows (that did not get enough sensitisation through underexposure) will be almost see through on the negative.

 

The general effect of pushing is to lose detail in the shadows, and this is why they say "expose for the shadows and develop for the highlights" - in exposure, you generally want to make sure you have enough exposure to get detail in the shadows, and in developing you are aiming to get a good (not too flat or too contrasty) negative.

 

To find out more about this I suggest googling for the zone system - this tells you about how light levels in the scene translate into negative and then onto print densities. I learnt about it by reading "The Negative" by Ansel Adams. The other thing you might want to google for is characteristic curves or H&D curves - these show the response of a film's density to light levels and development - the more development you give a negative, the steeper the density slope (and therefore the higher the contrast).

 

Hope this is useful

[ndjambrose]

Ah - I wrote the above as if you were doing your own. If you're sending it out to a lab it's even harder, as you have to factor in how much you trust the lab and the quality of their work.

 

B+W processing is super easy - you may not even need a course. There are plenty of videos on YouTube that show you how to do it, not to mention lots of forums and websites dedicated to explaining it in depth. A fair bit of expertise in this forum too.

 

And thanks for the comment about my work. The Sugababes was particularly easy so not sure how much I can take the credit - they're not hard to photograph ;-)

[tobey bilek]

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At the proper speed rating, you get details in the dark near blacks. Pushed film is underexposed and overdeveloped and the details in near blacks are lost.

 

The only way to get details in darks is to expose it there. There is no other way.

 

Classic rule is exposure controls the darks, development controls the highlights. This does not change and there is no magic developer that puts significant details in the shadows.

 

The increased development time make the neg more printable, but no more shadow detail appears.

[ndjambrose]

The only way to get details in darks is to expose it there. There is no other way....there is no magic developer that puts significant details in the shadows....

 

That's broadly true of single solutions, but not with two part compensating developers, which are more capable of bringing out shadow details. Hence my reference to Diafine, which is probably unsurpassed in that area.

 

An interesting video and some examples of TX pushed two stops, with results shown. As you'll see, in these examples Diafine brings out a very pleasant level of detail in the shadows even with two stop underexposure.

 

Processing Black and White Film for Scanning – Diafine and TX!

[Ruhayat]

Thanks again, Neil (and everyone else). I usually just tell the sales assistant to have the film processed as 800 or 400 depending on the speed I pushed it to. Is there any other info I should be giving them?

 

The girl who takes the orders is not so knowledgeable, but the shop owner is, so he might be able to interpret any other instructions. Asking him to use specific chemicals and processes might carry a cost, though... I'll try asking him that the next time. Hopefully I can experiment with your recipes once I know how to do it myself.

[Ruhayat]

I found this in a book, "The Complete Guide to Night and Low-Light Photography", by Lee Frost:

 

"The consequences of uprating and pushing film are that you get an increase in grain size, increase in contrast, and in some cases the appearance of base fog, which makes the image look rather washed out."

 

This "base fog" sounds like the phenomena I was talking of. I just wonder what causes it, though, since it only happens infrequently... only 1-2 frames per roll (sometimes none at all). Lighting conditions doesn't seem to be a factor -- one frame could have this fog, and then the next one I take on the same spot won't. Some kind of roullette that you just have to live with, then?

[Ruhayat]

Example of the "base fog". (This is someone else's picture, since I don't have a scanner to give my own examples):

 

2146/1819 on Flickr - Photo Sharing!

 

This fog gives you a greyish frame which is even more evident when viewed at smaller resolutions. Like you've put mosquito netting over your lens or something. I have 4-5 frames that looks like this.

 

This one also has slight fog:

2056/1715 on Flickr - Photo Sharing!

 

...whereas this one taken on the same night doesn't:

2144/1719 on Flickr - Photo Sharing!

 

You can quickly see which shots have it and which don't in this collection here:

http://fiveprime.org/flickr_hvmnd.cgi?search_type=Tags&photo_number=50&photo_type=250&noform=t&quicksearch=1&sort=Interestingness&textinput=m6+lucky+pushed

[ndjambrose]

Example of the "base fog". (This is someone else's picture, since I don't have a scanner to give my own examples):

 

2146/1819 on Flickr - Photo Sharing!

 

This fog gives you a greyish frame which is even more evident when viewed at smaller resolutions. Like you've put mosquito netting over your lens or something. I have 4-5 frames that looks like this.

 

This one also has slight fog:

2056/1715 on Flickr - Photo Sharing!

 

...whereas this one taken on the same night doesn't:

2144/1719 on Flickr - Photo Sharing!

 

You can quickly see which shots have it and which don't in this collection here:

The World's Best Photos of m6 and lucky and pushed - Flickr Hive Mind

 

Those are all examples of bad scanning, not bad development. Each of them lacks a proper levels adjustment which gives the impression of incorrect gamma - the 'fogging' you mention. It can be fixed instantly.

[Ruhayat]

Those are all examples of bad scanning, not bad development. Each of them lacks a proper levels adjustment which gives the impression of incorrect gamma - the 'fogging' you mention. It can be fixed instantly.

 

Ah. I see. The fogged photos I have also have this effect and they're straight from the printer, not scanned. The effect looks just like that cat picture -- it's consistent across the frame and not just concentrated in particular areas. I'm not unduly concerned, since it happens quite rarely, but I am interested to know what might trigger it so that I can take precautions.

 

Thanks for the insights into pushing. I think I sort of get it now. Of course, there's now the jungle of developers and processing times to look forward to. Whee.

[Xmas]

Hi

 

Try

 

ILFORD PHOTO - Push Processing

 

Noel

[Nikkor AIS]

For the best results @ 1600 asa and beyond kodak T-max 3200 is the the one. This shot here was taken @ 6,400 ASA on T-max 3200 developed in T-max developer. While pushing Tri-X and Even T-max 400 is possible for best results get the film made to push. As a base line follow the instuction on the package and tweek time/temperatue as required.

 

http://rogaltacdesign.smugmug.com/Other/Early-Work/Untouchable-1989/839775645_v6D5q-L.jpg

 

 

Gregory

[pico]

Most excellent comments.

 

Some people use a 15% sodium sulphite/water solution when pushing. This helps compensate, but also soften the grain which is apparent at the edges.

 

If the OP studies Adams' The Negative, he should be aware that the outcomes are far better than the book's pictures show. Reproduction does not do them justice.

 

Another very good book is Way Beyond Monochrome. Highly recommended.

[ndjambrose]

Ah. I see. The fogged photos I have also have this effect and they're straight from the printer, not scanned. ...

 

Unless you've specifically asked for optical prints your prints will have been scanned and then made digitally. Usually they're made on a Noritsu QSS or Fuji Frontier minilab scanner and then output onto photographic paper. The fogging you've seen can (and should) be removed at the scanning stage -- presumably it was not picked up by your printer's quality control.

[giordano]

Base fog affects the entire film, not just the image areas, and definitely not some pictures but not others. The area around the sprocket holes should be perfectly clear. If you suspect base fog, compare these areas with those on a film that was processed normally: if there's no difference then whatever the problem is, it's not base fog.

 

Base fog can be caused by exposure to x-rays and cosmic rays; by exposing the film to light before or during development; and by overdeveloping to such an extent that even areas of emulsion that weren't exposed to any light (e.g. around the sprocket holes) are partially converted into metallic silver - or a combination of them.