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FREE BLEACH BYPASS - A rookie takes a risk


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#1 Peter Anderson

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Posted 05 February 2008 - 01:00 PM

Just got off the phone with my local lab, a feature is currently having their stock Bleach Bypassed and they offered my stock a piggyback into their soup at no extra cost to a normail process. If i had the experience i would jump at the opportunity as this is the look i would be going for in my final grade but as this is my first S16mm shoot my nerves are getting the better of me. I shoot in two weeks and am happy to swot up as much as possible on the subject but i really need some worldy help and advice.

So lay it on me...I want to know everything possible about bleach bypass, perils and pitfalls included :)
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#2 John Holland

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Posted 05 February 2008 - 01:11 PM

It must depend on the look you want from your shoot . bleach bypass can be a bit extreme as say whats the subject matter ?
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#3 David Mullen ASC

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Posted 05 February 2008 - 01:23 PM

It must depend on the look you want from your shoot . bleach bypass can be a bit extreme as say whats the subject matter ?


If it's just a test, shoot a version with and with a bleach-bypass to the negative.

Since there is so much density added to the negative by leaving the bleach in, you may want to underexpose by one stop for that version, in which case you could also consider using a slower speed stock, since you'll get to rate it faster.

The main problem with a skip-bleach neg process is that your bright areas get overexposed faster.
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#4 Jonathan Bowerbank

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Posted 05 February 2008 - 03:45 PM

You may want to find out to what degree or percentage the bleach bypass is being run at, too. If it's a level you're comfortable with, take advantage of the savings!
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#5 Peter Anderson

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Posted 05 February 2008 - 03:56 PM

Im a littler confused about bleach bypass on film and on print and my understanding of intermediates is limited.
If anyone could enlighten me it would be much appreciated.
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#6 David Mullen ASC

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Posted 05 February 2008 - 06:29 PM

When you expose film, the exposed silver halide crystals become "developable" so that they are converted to black silver when processed (the unexposed silver halide grains remain silver halide). With color film, an equal amount of color dye is formed along with the silver during development.

The bleach step converts the silver back into silver halide so that the fixer and wash steps, which normally removed unexposed silver halide crystals, leave only color dye.

So if you skip the bleach step, you leave black silver in all the color dye layers formed.

On negative film, the greatest areas of density correspond to the brightest scene areas, so you get black silver in those areas when you do a skip bleach process -- this adds density, exposure, to the bright areas, making them hotter when viewed as a positive (by making a print or looking at in a telecine transfer.)

On print stock, the greatest areas of density are in the shadows, so the black silver left in by the skip bleach process makes the blacks blacker and the shadows darker.

So whether you do it to the negative or a positive, there is an increase in contrast -- but you see that increase mostly in the highlights when you do it to the negative (so bright areas burn out faster) and in the shadows when you do it to a positive like a print (so dark areas go black faster.)

You also get the extra grain from the silver, and since camera negative stock is faster (and thus has larger grains) than print stock or intermediate stock, a skip bleach process adds more graininess when done to the negative. It adds a little when done to the print but not as obviously.

You also are adding black silver into the colors, which can affect them.
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#7 Peter Anderson

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Posted 05 February 2008 - 06:39 PM

You also get the extra grain from the silver, and since camera negative stock is faster (and thus has larger grains) than print stock or intermediate stock, a skip bleach process adds more graininess when done to the negative. It adds a little when done to the print but not as obviously.


Ill be using the process on S16mm 250D. How much more grain will i be looking at? Im interested in a stark, desaturated clinical look so the bleach bypass seems more than suitable but now im worried about noticable grain.
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#8 David Mullen ASC

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Posted 05 February 2008 - 06:46 PM

Ill be using the process on S16mm 250D. How much more grain will i be looking at? Im interested in a stark, desaturated clinical look so the bleach bypass seems more than suitable but now im worried about noticable grain.


err... "7"?

How do you really quantify visible graininess (the RMS granularity number is pretty worthless)?

How objectionable grain is is a matter of personal taste and the degree of image enlargment, and the resolution of the post chain and presentation technology.

If you don't want more grain and were planning on doing a digital color-correction anyway, then don't do the skip-bleach to the negative.

As I said, since you can rate the stock a stop faster when leaving the silver in, you can compensate by using a slower stock, which has less grain.
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#9 Dominic Case

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Posted 05 February 2008 - 08:06 PM

How much more grain will i be looking at?

David's answer sums it up.

Graininess is a subjective quality - an expression of the visual impression of grain. Granularity is the objective measurement of the average size of the actual grains or dye clouds - but doesn't take any visual or perception effects.

Graininess (arising from bleach bypass or otherwise) always depends not only the stock, but also on the subject matter. Low light levels, shadowy subjects, large areas of out-of-focus background or uniform areas like blank walls, all add to the subjective impression of graininess: sharp focus, rim or back lighting, strong shapes and bold movement all distract from a grainy image structure. But the amount that you consider acceptable can only be judged by you and your director.

To put it another way: . . . . . test. Then test again.

One caveat. The normal advice for minimising grain is to overexpose the negative. In the case of bleach bypass, you need to underexpose the negative so it doesn't end up too heavy. Don't worry about the blacks not being black (which is the result of underesposure with normal processing. The contrast will be increased sufficiently for that to not be a problem.
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#10 Peter Anderson

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Posted 06 February 2008 - 03:14 AM

ok so not an easy question to answer - and it seems i was naive in thinking that it could be responded with 'a lot' or 'a little'. My budget is fully stretched and i wont be able to test so It looks like ill have to forego the process. It feels like a shame to miss the opportunity to get experience with a negative process - Faking it digitally doesnt have nearly the same appeal and feels like a compromise in my exploration of cinematography.
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#11 Kevin Zanit

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Posted 06 February 2008 - 04:20 AM

I would not go in blind either. I don't know if it helps, but I posted some of my bleach bypass tests here:

http://www.cinematog...mp;#entry170410

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#12 David Mullen ASC

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Posted 06 February 2008 - 12:03 PM

ok so not an easy question to answer - and it seems i was naive in thinking that it could be responded with 'a lot' or 'a little'. My budget is fully stretched and i wont be able to test so It looks like ill have to forego the process. It feels like a shame to miss the opportunity to get experience with a negative process - Faking it digitally doesnt have nearly the same appeal and feels like a compromise in my exploration of cinematography.



Then find a way to shoot a test!!! How much can a 100' of film cost to test? Or look at someone else's test at the lab.

No one is trying to talk you out of something.

If you're going to be a cinematographer, you've got to figure out ways of trying out new processes. You said you've got two weeks, plenty of time to shoot a test.
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#13 John Holland

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Posted 06 February 2008 - 12:29 PM

I think this guy is a student at a film school [total guess] so 100 ft film lab costs would be quite a lot over here if you have zero budget ,
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#14 David Mullen ASC

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Posted 06 February 2008 - 12:33 PM

I think this guy is a student at a film school [total guess] so 100 ft film lab costs would be quite a lot over here if you have zero budget ,


They are about to shoot a short film and expose hundreds of feet of film... and they can't afford to expose 100' for a test? He already said that the lab wasn't going to charge extra for the bleach-bypass, which is often a $500 set-up fee.

Or if it's just a student film, why not take a chance and use the process? At least the short itself would become your test and you'd learn something.

If you really want to do something, you have to be clever about making it happen.
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#15 John Holland

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Posted 06 February 2008 - 12:39 PM

As i read his first post he shoots in two weeks time so that when the freebee bleach bypass is available so just asumed he cant get a free test before hand .
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#16 David Mullen ASC

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Posted 06 February 2008 - 12:42 PM

As i read his first post he shoots in two weeks time so that when the freebee bleach bypass is available so just asumed he cant get a free test before hand .


Yes, that may be true... though you'd think this show using the process for two weeks must have shot some tests themselves, or the lab must have some samples of Super-16 that has been bleach-bypassed so at least some opinion can be formed about the grain.

Adding grain is inherent to the process. So saying "I love it because it's organic but I don't want grain" is a little like saying "I love grass because it's organic but I hate the color green." The process: #1 adds grain, #2 adds contrast, #3 reduces saturation.

If all you want is #2 and #3, then there are other methods, like digital color-correction, optical printer work in a S16 blow-up process, thru combining color & b&w intermediates, even half-digital / half-film approaches (like shoot reversal for a lot of contrast, then reduce color levels digitally.)
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#17 John Holland

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Posted 06 February 2008 - 12:50 PM

David i am on your side spent my whole film life bending the rules and trying to prove film manufacturers that you can do what ever you want to their products and make the finished item look more interesting always been a rebel . Mind you never have been a great fan of bleach bypass .
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#18 Peter Anderson

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Posted 06 February 2008 - 04:44 PM

I am a student and this is my first 16mm shoot which is why i may seem overly aprehensive. The budget is completely maxed and we're relying a lot on freebies and the generosity of those with experience to help out on what is currently a very ambitious project. If i could have secured any more tests on stock i would have but believe me, its an option that has been exhausted.

Also, Ive not been talked out of anything but I wouldnt feel confident going ahead with something i have limited knowledge of - My intention with the topic was to get as much information as possible.
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#19 David Mullen ASC

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Posted 06 February 2008 - 06:39 PM

If this is your first 16mm shoot... wouldn't you like to see what 16mm normally looks like before you start experimenting with special processes? How are you going to have a frame of reference?

You've got to learn to walk before you learn to run.

"Master your instrument, master the music, and then forget all that poop and just play." ~ Charlie Parker
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#20 Dominic Case

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Posted 06 February 2008 - 07:57 PM

Also, Ive not been talked out of anything but I wouldnt feel confident going ahead with something i have limited knowledge of - My intention with the topic was to get as much information as possible.

Seems like a good result then :rolleyes:

It does sound as though you will have a big enough challenge getting everything right anyway - without the extra risk of non-standard processes. As David says, get the feel of normal stock first. Processes like bleach bypass need lots of testing - and even then there can be unexpected surprises when you actually shoot.

Still, cinematography.com has provided you with heaps of information that you can refer back to another time - when you are ready.
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