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h_A_Z

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Hey guys. I just got myself a M6 and very new to film. My Q is this, lets just say I put in a 400 film and set the knob at the back to 800, will my film me faster compared to if I just set it to 400? Where can I get more info on this? Looked thru all the threads but cannot really find the answer to it. Sorry if this really sounds like a silly Q. Thanks guys

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Hey guys. I just got myself a M6 and very new to film. My Q is this, lets just say I put in a 400 film and set the knob at the back to 800, will my film me faster compared to if I just set it to 400? Where can I get more info on this? Looked thru all the threads but cannot really find the answer to it. Sorry if this really sounds like a silly Q. Thanks guys

What does "will my film me faster compared to if I just set it to 400?" mean?

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Guest jarski

if you use different than true speed, developing should take this into account.

 

those who are developing their own films probably can give precise info and some links to study.

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Hey guys. I just got myself a M6 and very new to film. My Q is this, lets just say I put in a 400 film and set the knob at the back to 800, will my film me faster compared to if I just set it to 400? Where can I get more info on this? Looked thru all the threads but cannot really find the answer to it. Sorry if this really sounds like a silly Q. Thanks guys

 

The underlying sensitivity of the film does not change. If you set the dial on the back to 800, then you will effectively be underexposing by one stop if you follow the meter.

 

If you subsequently get the film developed as normal, then all of the images would be a bit 'thin' and unsatisfactory.

 

If you get the film developed 'push 1 stop' (more time in the developer usually), then you will get negatives with a good density, but they will be a little more grainy and I think more contrast as well. It's not uncommon to do this, so as to be able to shoot in lower light or to get the grain/contrast effect.

 

Note that once you start shooting the roll of film at a particular ISO then you need to shoot the whole roll at that ISO, because the 'push developing' applies to all of the shots.

 

One thing to keep in mind, the M6 has a maximum shutter speed of 1/1000. If you shoot at 800iso, then on a nice sunny day you will forced to stop down to f11-16 in order to keep within the shutter speed limit. Usually I end up shooting at 400iso, and carrying a 3 stop neutral density filter so that in bright sunlight I can still have some variation in aperture.

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It's called "pushing" film, and you won't go to gaol for it. What it means is you are rating the film at a higher speed, and this is taken into account during processing. Tell the lab. Yes, you can do it and the film is indeed faster. Some films can be pushed more than others. I've never seen much point in it -- better to load an 400 or 800 ISO film in the first place. Unlike digi, you can't change the ISO halfway through the roll!

 

Enjoy the M6 -- it's a terrific camera! And do also try some slide film.

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That's not strictly true, David.

 

I have been in a situation where I had one minute to try to get a shot in a situation that would never repeat itself. I was about 5 shots into a roll of Tri-X. So, I set my M7 dial to 1600, took what I could inside a dark room, then put it back to 320 when I left. I developed to film as I normally do, and still got useable negs from the 1600.

 

All that this proves is that Tri-X is an amazingly flexible film, but in extremis, anything is worth trying.

 

I wouldn't normally do this of course, nor would I push film that hard. (I actually pull all my b&w film)

 

The massive development chart at digitaltruth.com is a great place to start if you want to push develop your own film

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My only experience of pushing (or it could have been pulling) was by mistake (i.e., forgetting to adjust the film speed dial). Results -- with color neg 400 as I recall, weren't too bad.

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Technically speaking, your film "ISO" will NOT change - instead, you will need to become familiar with the term "EI" ("exposure index"). As in "I shot my ISO 400 film at an EI of 1600."

 

ISO is the specific film speed measured by the manufacturer according to International Standards Organization (ISO) procedures and that does not change regardless of how you set the meter - EI is what you choose to set on the meter, if different than the ISO.

 

"Pushing" film, as mentioned, means setting an EI higher than the ISO, and then increasing chemical development (either through more time in normal developer, or by using a special high-activity developer) to generate more silver from the underexposed crystals.

 

>>>The extra development is a required part of the process - changing the meter dial alone isn't enough. You must add development time if processing the film yourself - or be sure to tell the lab you need push processing if using a lab. <<<<

 

("Pulling" film means setting the EI lower than the ISO, and then underdeveloping to prevent too much silver forming in the final image - usually to lower contrast in contrasty scenes).

 

Color negative films (and the B&W films that run through color neg chemicals, like Ilford XP2) do NOT take pushing very well - the shadows become very thin and noisy and the colors go off. One stop at most.

 

Color slide films get grainy but can usually handle up to a 2-stop push (i.e. 400 ISO to EI 1600)

 

Some traditional B&W films take pushing very well - up to 3 stops, or 4 depending on one's standards. There's a long history of dramatic low-light shots made with "pushed" ISO 400 films from an era when there were no films of ISO 800 or 1600.

 

The rule of thumb is - increase development time by 40% for every doubling of EI.

 

1 stop = 1.4x the time = 400>800

2 stops = 2x the time = 400>1600

3 stops = 2.8x the time = 400>3200

4 stops = 4x the time = 400>6400

 

Grain increases - because you are basically building up more silver on the few exposed crystals through extra development to replace silver lost to crystals that never got enough light.

 

Contrast increases because the shadow areas, which were already not getting much light, don't get enough to react at all (don't reach exposure threshold), whereas the bright areas are getting more and more silver added through the extra development.

 

The attached shot (ISO 400 Tri-X or HP4 exposed at EI ~6400 or more - rural racetrack lighting and a 28mm f/3.5 lens) gives an idea of how pushed B&W images look - inky, completely blank blacks and only the brightest areas registering much at all.

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This is one of the ones I pushed to 1600, but which was developed as if 320

 

Inside Oskar Schindler's factory, Krakow

 

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Thanks for the replies guys. The thing is I am so used to using digital which means I can change ISO whenever I need a faster shutter speed. I guess there is alot to learn with film :)

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h_A_Z,

This answer may go beyond your needs, but it is a trick that not many know about. If you use a C-41 process B&W film, it has essentially no grain (it has no silver halide crystals, only layers of light-sensitive dye) and will tolerate all sorts of abuse in terms of under and over exposure, as long as you develop it in a compensating developer such as Diafine (which has the same development times for all films at all speeds) you can even change ISO during the roll and the film is still to be developed the same way. If you are ever in some out of the way place and the only film you can find is a C-41 colour film, you can do the same thing - but obviously with Diafine or similar you are going to end up with B&W negatives (and they will have the usual orange film base, but they will scan OK). I prefer some grain, myself.

 

You shouldn't worry about this yet. At your stage the rules should be that you set ISO correctly, and don't change it mid-roll. It does mean you will sometimes have the wrong film loaded for the conditions/subject/time of day - but that's film, and planning ahead and being prepared are part of what you learn. The only way round is to carry a second body so you can have fast and slow films, or colour and B&W. I suppose you could use a flash too, but I prefer to avoid them. Later you can play with exposing whole films at speeds other than the ISO marked on the box. As far as I know the only way to change mid-roll is to use a compensating developer, and even then, I don't bother - after all if I change the ISO because it's darker I may underexpose the shot by, say, two stops. If I don't change the ISO I will end up doing the same within the limits of my fastest aperture and slowest shutter speed I can hold. The film and the developer won't know the difference, only the meter in the viewfinder will say anything different. And I might forget to change it back.....

 

BTW, developing B&W at home (especially with time-insensitive developers like Diafine) is actually easier than getting to the post office and sending your film away!

 

Chris

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H A Z,

 

Even in digital you are not changing the characteristics of the sensor; it only has one true ISO. The underexposure in digital is also made up in processing.

 

No one mentioned "pulling" film. That is shooting at lower ISO than the rating. It too is made up in processing, by developing less. The contrast is lower.

 

So you can increase contrast by pushing; and you can decrease contrast by pulling. Now that is what the Ansel Adams Zone System is all about. Measure the contrast of the scene with a spot meter; determine the contrast range you need; and then expose / process to get the right contrast from the filem. Works well with single sheet view cameras. I guess if you carried enough Leica bodes you could do the same thing with 35mm film.

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Technically speaking, pushing film in development doesn't increase film speed. You might get a 1/3 of a stop extra, but that's about it.

 

Saying that, there are perfectly good reasons for pushing film (underexposing and compensating in development), especially if you are printing in a darkroom and/or like higher contrast pictures.

 

If you are scanning, you can get quite far in photoshop compensating for underexposed images that have not had their development compensated. You do this by increasing the contrast. If you do extend development, things work a bit better in my experience, particularly with grain in the shadows. Less manipulation is then required in photoshop.

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What Adan said. It's worth remembering, though, that the ISO number on the film cassette is the manufacturer's recommended exposure index, which may or may not be the same as the actual ISO speed, though it's probably pretty close.

 

Andy's story a few posts back

So, I set my M7 dial to 1600, took what I could inside a dark room, then put it back to 320 when I left. I developed [the] film as I normally do, and still got useable negs from the 1600.

could mislead inexperienced people. It only made sense to set the M7 dial (i.e. the EI) to 1600 if Andy planned to push-process the film accordingly. If he intended to stick with his usual processing he'd have done better to leave the EI at his usual 320. That way, anywhere there was enough light he'd have got a "correct" exposure, and in other places he could have set the camera for maximum hand-held exposure (e.g. 1/15 at f/1.4) to minimise the amount of underexposure.

 

Using EI 1600 instead guaranteed that all the interior shots were underexposed by just over two stops. I guess that Andy subsequently decided that the interior shots weren't important enough to be worth sacrificing the rest of the roll for.

 

The true lesson from the story is how much exposure latitude B&W film can have - especially when there's a really skilled person making the prints.

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John

 

Like I said. The shots I took at 1600, but developed at 320, were useable. There's one shown above.

 

I also explained that this is due to the flexibility if Tri-X. If I'd had long enough to take a whole roll there, I'd had processed it at 1600. As it was I was there long enough for about 4 shots. I'm too tight to throw away the remainder, as 1600 is unusable in normal daylight conditions.

 

I don't have a Summilux, btw. Not everyone does.

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>>>The extra development is a required part of the process - changing the meter dial alone isn't enough. You must add development time if processing the film yourself - or be sure to tell the lab you need push processing if using a lab. <<<<

 

Color negative films (and the B&W films that run through color neg chemicals, like Ilford XP2) do NOT take pushing very well - the shadows become very thin and noisy and the colors go off. One stop at most.

 

I read on another thread that the XP2 is pretty forgiving for the purposes of pushing and pulling. Not right then?

 

If I push the XP2, do I have to tell the lab to push process, or is push (or pull) process necessary only for "real" black and white?

 

Thanks!!

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John

 

Like I said. The shots I took at 1600, but developed at 320, were useable. There's one shown above.

 

I also explained that this is due to the flexibility if Tri-X. If I'd had long enough to take a whole roll there, I'd had processed it at 1600. As it was I was there long enough for about 4 shots. I'm too tight to throw away the remainder, as 1600 is unusable in normal daylight conditions.

 

I don't have a Summilux, btw. Not everyone does.

 

So when you took the shots, you got enough light on film to register an image. The film was still 320 or 400 ISO and was processed normally without additional contrast. The setting on the camera is simply for the meter, not the film. The way you metered the scene was such that instead of getting a shot that was two stops underexposed, you got one that was closer to what would be correct for ISO 320. This was either by accident, equipment error, or else you simply had enough latitude on the film to get a enough density for the image to work acceptably for you, even though it was underexposed. "Correct exposure" does not really have a general definition. Tri-X does not have so much exposure flexibility when compared to a double layer film such as Plus-X which can still produce decent images after extreme over exposure.

 

There is a fair amount of lack of technical understanding on this thread. Adan has it down... listen to him. My first year text on this subject was "Photographic Sensitometry" by Todd and Zakia. That book will explain it all to you if you care to read it. But this subject is becoming pretty antiquated.

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Back when dinosaurs roamed the earth, I was intrigued with the concept of "available darkness" photography. Armed with my Leica III & trusty Summarex loaded with Agfa Isopan Record, I explored dim light at ISO 12,000 ( a 31 minute push in 1:40 Rodinal ). The results were unique. The images, as printed on a grade #6 Brovira, looked like a Navaho sand-painting. They could be reproduced without a half-tone screen. The lesson: just because you can do it doesn't mean you should. The QUALITY of light is more important than the quantity. I switched to ISO 20 films, to truly appreciate my Leitz lenses.

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