Basic film question

[pridbor]

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Being new to film, gone for 12+ years as many of you here, now having to ask simple basic question of you gents. So is it possible to change the ISO setting on a per photo basis, that's extreme I know but...like going from a 200 film to a 100 or 400 setting due to the scene?

 

Even when I used to shoot film before have I ever done so nor thought about it, not professional mind you just an eager amateur. I have both R and M cameras, the M7 very new and never seen the dial on the back before, so real newbie on M system.

 

Thanks in advance

 

Preben

[pico]

Presuming that you are talking about B&W film here.

 

Film has exposure latitude, although accomplished experts would not suggest that one rely upon it. A stop on either side of the stated ISO is going to yield an image. In other words, if you have ISO 400 film, you can suffer through an exposure of ISO 200 or ISO 800.

 

If you shoot a C-41 film, the latitude is greater.

 

Very much of the B&W work shown here is not exposed 'properly', but the results succeed.

.

Edited November 11, 2016 by pico

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[gbealnz]

Never tried it, but wasn't that an "attribute" of Ilford XP1?

Gary

[chris_livsey]

Modern C41 colour film has around 14 to 15 stops dynamic range (depending on how you tolerate/can scan/use the toe/ and the top roll off of the curve) a standard scene, if such a thing exists, has 5 to 8 stops so you will have up to 5 stops up or down to move for excellent results, more if you do some work on it.

 

There are numerous posts showing this latitude, here is one showing Portra 400 up to +10 stops over base exposure:

 

http://www.johnnypatience.com/download/johnny_patience_portra_400_0_to_10.jpg

Which, interestingly, is the only one I know of that directly compares two commercial scanners from the same Lab.

 

Here is another showing different film stocks:

 

http://canadianfilmlab.com/2014/04/24/film-stock-and-exposure-comparisons-kodak-portra-and-fuji/

 

And note that perhaps counterintuitively B/W film is less tolerant.

http://canadianfilmlab.com/page/2/

 

 

Exposure on film is very different from digital in several ways and similar in some.

No "hard stop" : Digital has a hard cut off with overexposure over 255 (is it?) no data, full stop, film rolls off at the top increasing exposure produces progressively less effect.

They are similar in the toe: Digital disappears into the noise floor but not in a hard way, the cut off is dependant on your RAW process capability and camera noise handling and your tolerance for noise in the shadows, film is similar but you have less manipulation but scanners vary in what they can "see" in the toe.

 

200 to 400 is a walk in the park unless your subject has a massive tonal range and yes exposing "properly" obviously optimises quality but 1/3 stop you would be pushed to see without a densitometer, the old point and shoot and they weren't called that, "box" cameras had at best two speeds usually one and three f stop settings, they worked because film is tolerant and modern film is vastly more tolerant.

 

Remember, if you are selling expensive meters or sophisticated in camera metering or offering a workshop or a course or just writing an article/blog these facts may not suit your marketing message that high skill and expensive equipment is required to have a chance of producing a usable image at all.

 

Finally yes that is how C41 B/W like XP1 worked it wasn't magic it was science.

 

And to really stir the pot the Ansel Adams et al Zone System was specific for individual exposures on sheet film whose emulsions are no longer made and bear scant resemblance to modern coatings, it is incredibly good to understand it and appreciate seeing the light but not to "impose' it as a current world view of how to work with pleasure in film.

Edited November 12, 2016 by chris_livsey

[pridbor]

This requires my reading iyour text and the links more than once! I assume that "over the top" relates to overexposure and that "in the toe" to the other end of the scale namely under exposure? If so why doesn't digital cut off hard at "0"?

 

Thanks

 

Preben

[chris_livsey]

This requires my reading iyour text and the links more than once! I assume that "over the top" relates to overexposure and that "in the toe" to the other end of the scale namely under exposure? If so why doesn't digital cut off hard at "0"?

 

Thanks

 

Preben

 

Whilst it is not essential to know about film curves to take excellent photographs when discussing dynamic range and latitude, which is what your OP was about essentially, it helps.

 

This curve is usefully and rarely marked in fstops so makes it more easily understood, sorry about making you click again 

http://motion.kodak.com/KodakGCG/uploadedfiles/motion/TI2647.pdf

page 4 top RHS

(Don't worry about the tungsten and funny process this is movie film it's just a good graph to understand a curve)

 

The "best" and recommended for highest quality results is to place your exposure on the straight line portion, the "over the top" as you say is high exposure where you can see the curve begins to loose "straightness" only just on the remarkable film at +8 stops.

The toe is at -6 -7 ish where the incoming light is not enough to fully 'activate" the light sensitive crystals in the emulsion so you get underexposure.

 

In digital the photoreceptor site has a hard top as I said because at some point the incoming light fully saturates the receptor so more light has no more effect on the output, at the other end the cut off is not abrupt as light, as single photons, will continue to register a signal down to zero EXCEPT there is no hard zero because the receptor site, and the electronic circuits associated with it, have electrical noise that generates random low level signals, the light registered disappears into this noise floor. The point at which zero is declared depends on the electronics, the standard for noise set and the ability of RAW processors (including the in camera one if you shoot jpeg) to "dig out" a useful output at the bottom between noise and signal know as the signal to noise ratio S/ N.

 

Simple advice is if shooting colour as C41 negative film set your M7 to one stop overexposure so for Portra 400 set 200 that is because as you will have seen on the many links   overexposure is "safer" for getting good colour and a result, this is counter to digital where the highlights must be protected (against that hard top they have).

 

On B/W start at box speed then try up or down even half a stop where you will find the results you aesthetically want by experiment.

 

I doubt you are shooting E6, reversal colour film, but if you do treat it as digital, box speed and spot on exposure, this is because E6 has much lower dynamic range and therefore much less latitude, this is the nature of the E6 emulsions.

[pico]

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About exposure: an associate of mine shoots 4x5" and intentionally overexposes to a remarkable degree so that his enlargements have long exposures,  and his prints are remarkable. Go figure! I'm not smart enough to understand

[Tom R]

About exposure: an associate of mine shoots 4x5" and intentionally overexposes to a remarkable degree so that his enlargements have long exposures,  and his prints are remarkable. Go figure! I'm not smart enough to understand

 

That's not so incredible, assuming that they are doing their own processing. If I recall correctly (it's been a few years), I would regularly pull/push 35mm films and then compensate by plus/minus 20% development times, or sometimes change the developer all together. I'm betting that only worked on older emulsions, however. Moreover, I don't know how many people mix their own soup: for example D23 (D-76 modulo the hydroquinone and borax (IIRC)) was great for pulling 1-2 stops, whereas Gene Smith would soup Tri-X 2:1 (that is ... the opposite of 1:2 parts developer to parts water), and expose Tri-X at 1200-1600 given the conditions, etc.

 

I am confident that many contributors to this forum have much information they could provide on exposure latitude --especially for B+W films.

[philipus]

At the risk of stating the obvious, rather than go through the hassle of changing ISO per shot, just adjust aperture or shutter speed to get the same result.

 

I've shot rolls of Portra 400 this way from about EI100-EI1600, in indoor settings. There will be post-processing necessary to get acceptable images but if that's the only film one has (or one doesn't have a flash) then it's better than no picture at all. 

 

Like others have said going a stop above or below will usually be completely fine with C41 or B&W. In fact, I virtually always overexpose by C41 by up to two stops (meaning I shoot all my Superia 400 at EI100 and my 200 at EI100 or even EI50). For a hybrid, scanning workflow, having extra light in the shadows is beneficial for reducing scanner noise in these areas of a photo. 

 

Br

Philip

 

Being new to film, gone for 12+ years as many of you here, now having to ask simple basic question of you gents. So is it possible to change the ISO setting on a per photo basis, that's extreme I know but...like going from a 200 film to a 100 or 400 setting due to the scene?

Even when I used to shoot film before have I ever done so nor thought about it, not professional mind you just an eager amateur. I have both R and M cameras, the M7 very new and never seen the dial on the back before, so real newbie on M system.

Thanks in advance

Preben

[EoinC]

I generally overexpose my B&W films by 1 stop against box speed, and carry this through until hitting the limits imposed by aperture / shutter speed (I try, unite successfully, not to carry tripods and ND filters). When I reach either limit, I start "trading off" to stay where I want, until the 2nd limit kicks in. Once that is reached, I generally trade off exposure for getting a shot, which may or may not be terminal.

 

All of this is generalised, as there are times when 'correct' exposure is not what is desired (eg wanting silhouettes).

[Guest]

You can use stand development for varying ISO in different frames on the same roll. I wouldn't do it for merely going from 100 to 200 ISO, but from 400 to 800 and 1600 makes more sense. For Tri-X, for example, you can use a 1:100 dilution of Rodinal for 1 hour, inverting gently after 30 minutes. What you need to do is to use at least 3.5 ml of Rodinal per 35mm roll. So, when you dilute 3.5 ml of Rodinal in 350 ml, you make have to sure that your tank is large enough to use all of the diluted developer. Some small one-roll tanks have a only 240 ml capacity; filling one of these will give you 3.5 ml of Rodinal and will result in underdevelopment — I just experienced this with a lab and my negatives that were correctly exposed came out extremely underdeveloped ("very thin"): you can tell because the TRI-X writing and frame numbers were so light on the negative as to be virtually unreadable.

 

You can do a web search on stand development to see why this works. Stand development seems to be controversial but I like it, particularly when there are very bright highlights, as in harsh tropical light. Here are four shots from the same roll using stand development, two exposed at ISO 400 and the other two  at ISO 1600. (Incidentally, the last photo is taken in horrible, flat light in a chopping center basement).

 

 

M6 | TRI-X @ 400 | Summilux-35 ASPH-FLE | Stand development

Chiang Mai

 

 

M6 | TRI-X @ 400 | Summilux-50 pre-ASPH | Stand development

Chiang Mai

 

 

M6 | TRI-X @ 1600 | Summilux-35 ASPH-FLE | Stand development

Chiang Mai

 

 

M6 | TRI-X @ 1600 | Summilux-35 ASPH-FLE | Stand development

Chiang Mai

 

_______________

Alone in Bangkok essay on BURN Magazine

Edited November 13, 2016 by Guest

[philipus]

Very nice photos, indeed. One can also use Diafine which is considerably quicker than stand and, in my experience, gives much more consistent results. Also allows developing different kinds of B&W roll in the same tank which is convenient.

 

You can use stand development for varying ISO in different frames on the same roll.

[250swb]

At the risk of stating the obvious, rather than go through the hassle of changing ISO per shot, just adjust aperture or shutter speed to get the same result.

 

 

The bit above needs saying again, this thread should be titled 'over or under exposing film on the same roll' and all changing the ISO is doing is fooling the meter, and clearly sometimes the photographer.

[chris_livsey]

At the risk of stating the obvious, rather than go through the hassle of changing ISO per shot, just adjust aperture or shutter speed to get the same result.

 

Philip

 

It's the legacy of shooting digital which is why I launched into my rather long winded explanations of how film works differently missing that excellent point.

[Guest]

The bit above needs saying again, this thread should be titled 'over or under exposing film on the same roll' and all changing the ISO is doing is fooling the meter, and clearly sometimes the photographer.

 

Yes, but by the time you've reached the maximum aperture of the lens you're using, say f/2 (or less if you need for DOF reasons), and the fastest shutter speed that won't blur the subject, say 1/60 sec or faster, you'd better be conscious how many stops you want to push the film in development (assuming you've seriously underexposed most of the frames on the roll) — and for that it's useful to reset the meter's ISO from, say 400 to 1600 and think in terms of needing to push the development two stops. A lot simpler and less error-prone than keeping the meter at 400.