Dumb Question On Exposure

[DRabbit]

I'm just now exploring film for the first time (seriously). I've been into photography since the dawn of digital though and have come to learn about exposure, so I do understand how aperture, shutter speed and ISO all work.

What I don't understand is film speed and how it relates to ISO settings on the camera. With digital, increasing ISO increases sensitivity and results in more noise.

I know from the old film days that very high ISO films are grainier. In those days though, I was only using automatic cameras.

Lets say the film is ISO 400. With the camera set at ISO 400 I'd expect "normal" exposure rules.

I assume but increasing the ISO setting on the camera to 800 that would increase sensitivity and allow me to shoot at a faster shutter speed or smaller aperature.

But how does that work exactly? Can you increase the sensitivity of 400 film? OR does the way the camera is set always have to match the film? Does it let more light in at the expense of more grain, or is that just a product of the film itself? Is that what "pushing" means? (I feel really stupid).

I feel REALLY dumb asking this questions since I've been taking photos for a long time... but the film world is new to me, so I hope you'll allow my ignorance and help a girl out 😉

Thanks...

 

[italy74]

Ciao Amy
A few things to answer you:
1) whatever camera reads a so-called DX code which is on the film roll, so everything is automatic. For what I know, the only film roll (if still on the market) where you have to set manually that code is a b/w slide made by Scala. However I personally advice you not to use a whole roll manually set to another DX value than that expected. If you would ever do so, you have to tell to who prints the pictures because he will adjust his printing parameters to the shift you did. Keep in mind however that a + 1 EV (from 400 to 800) usually won't affect that much the image, but it will result grainier and you might lose some contrast or having too much in the shadows. In general, the IQ will be worse but still acceptable unless you have to use them professionally

2) Another simpler method to "fool" the preset iso value is - like on digital - turning the exposure compensation dial on your camera. Again, + 1 EV usually is not a problem, over that value you have to consider what you're shooting: slides are of course much more sensitive than negatives or (even better) b/w film rolls which have usually the highest pushability among film. Some claim you can get even + 4 EV, I wouldn't go over + 3 in any case. Here you get the same effect explained above: a worse IQ but you might easily deal with that.

Slides: + 1 / 1.5 EV at MOST (slides must be usually exposed for the lights, so they will give their best underexposing them -0.5 EV)
negatives + 2 EV at most: they must be exposed for the shadows and thus is good having them overexposed +0.5 EV
b/w: as I told you, if you have a very good one who develops and prints manually, you could try to work within the + 3 EV at most but this will however make your images much worse. In this case, I really suggest point 3) here below.

3) of course the simplest thing is changing roll 😉

4).. by the way which camera do you have?

 

[DRabbit]

Hi Dino,

So let me make sure I understand. ISO setting on the camera, in theory, should match that of the film. In practice, the camera will automatically KNOW what ISO the film is (because of a code on the canister). My obsessive nature means I'll set the camera to match just to be safe 😉

And generally speaking, you can't, or typically don't want to, change the ISO as a means to adjust sensitivity. You use exposure compensation for that.

Did I get that right?

I haven't bought the camera yet. I'm leaning towards the Zeiss Ikon ZM or the CV Bessa R3a. 35mm Rangefinder is my medium of choice right now 🙂

 

[DRabbit]

Wait wait wait... just a thought... the setting on the camera for ISO, is that what is telling the built-in meter (if there is one) what to meter the incoming light against? (hope that makes sense)

 

[MartinP]

I'd suggest Googling for H&D curves (Hunter & Driffield, two early researchers, graphs showing density and log exposure) and other sensitometry related information. I don't have a handy source online unfortunately. You could also look at a library copy of Basic Photography (Langford).

The silver in any particular film is affected by light in only one way, depending on the size/shape of the grain, built in sensitizers etc. so what you do in 'pushing' is make what would be a thin area of silver (not much affected by light) a bit thicker by increasing the development time and growing the clumps of silver-grains a little more. The problem is that your entire picture then has less available density range between black and white in the scene, compared to the part of the film range affected.

Some films are designed with very long, flat H&D curves to enable a variety of changes in exposure-index depending on how you choose to use it. Typical of this sort of film is Ilford Delta 3200. Note that the ISO rating is only a carefully standardised test to give an indication of how a film behaves, so lots of people make little adjustments in their own work. The manufacturer's data is generally an optimal compromise though, so one doesn't 'have' to change anything really !

There are lots of people with more knowledge and more teaching ability here though. For example, you could also have a look at Roger Hicks website for good explanations (there is a link over to the left side of the RFF site).

Good luck, and have fun.

 

[Al Kaplan]

In general both B&W and color negative films can be under or over exposed by one stop without disaster while slide films need more accurate exposure. Color negative films for some reason (too complicated to explain here) give slightly finer grain when slighty overexposed but you risk losing detail in the highlights. Overexposed B&W will be grainier.

Getting back to B&W, the development affects both film speed and contrast but you either have to do your own or use a custom lab. NO, you can't do some frames at 100 and others at 400 on the same roll. If you want top quality results the code on the film cartridge may or may not give it to you. You'll have to shoot and process a few rolls to find out. Shutter speeds aren't always accurate, meters aren't always accurate, your developer might be giving your film more or less sensitivity, and you have to standardise the way you measure the light, such as taking a reflected reading off a grey card or using an incident light meter.

 

[italy74]

Ciao Amy
sorry it's me who had mistaken, of course I forgot we're on a RF site so you effectively MUST set the DX value BEFORE shooting (if you will go for a Zeiss Ikon (highly recommended), there's an upper dial to turn) - sorry, I was thinking with an SLR mindset. Once ISO dial has been set, the camera will be able to evaluate the CORRECT shooting times depending on the film roll you have put on it. Of course if you set it wrong, the camera just doesn't know that and will expose for the setting YOU did. She won't care your pictures will be later darker / brighter than necessary. She (its exposure meter) will reason with the ISO that YOU set.
Then yes, to have faster shooting times the simplest thing is working with the EV compensation dial

About your other question, it often happen that, for one reason or the other, or just for your sake, you work with compensation dial, but this is usually limited to a particular shot or series of shots that require an adjustment (i.e. a bright white bride dress or wall or a large black/shadowy area..)

PS another thing: be aware that while Zeiss Ikon might be better overall and BETTER for wide angles, the R3A has a particular viewfinder which makes it better for longer lenses (from 40mm onwards) so it's necessary to know what you like to shoot. Within 50mm (if you can afford that) go for the Ikon, otherwise the Bessa might be your choice

Remember I'm talking focal-lenght wise ONLY, depending on the characteristics of the viewfinder

 

[DRabbit]

Again, thanks for the info.

So, generally speaking, on a RF, the setting on the camera should match the ISO rating of the film. The setting on the camera itself is what tells the camera how to expose the incoming light against the film being used. (did I get that right?)

Thanks for the search tips Martin... I'll do some googling.

Al: I figure there will be some testing on my part to see what films I like best and how they work. I'm starting with B&W Arista Premium 400 because I've heard it's similar to Tri-X, which I have liked in looking at others' photography. Initially I won't be doing my own developing, but I did find a good local lab that a couple of photographers I know use. I'll be doing my own negative scanning.

 

[italy74]

Yes Amy,
if you want your pictures correctly exposed you should match camera dial with the iso on your roll; of course you might want to experiment a little and in the end is your choice setting which iso for which roll.

 

[Al Kaplan]

That should work! Just try to start out using one film at one speed. Learn one thing at a time. As you go along ask the guys or gals at the lab for advise and suggestions too.

 

[DRabbit]

You guys rock! Thanks so much 🙂

 

[italy74]

Pay attention Amy,
film is way more addictive than digital if you're bitten.... 😉

 

[DRabbit]

LOL Dino... Hey, this all started because I bought a thrift-store Polaroid camera a few weeks back. Since then I bought 3 others and now I'm on the hunt for 35mm film cameras... I think your warning has come too late 😛

 

[italy74]

Just a question...
were you shooting with a M8 or RD1 to be interested in RF ? Or is it a "street photography" thing and everyone told you that RF is usually better? or just that SLR are too bulky?

However, if you could ever afford that, I'd strongly suggest a Biogon T* 2/35 to be coupled with your Ikon. Both silver if you like them trendy or black if you want to be even stealthier

 

[DRabbit]

I have an M8 and RD1. I feel like I want to explore film and since I LOVE shooting with a rangefinder, looking for a film one (rather than a film SLR) makes the most sense.

I already have the 35 f/2 Biogon. LOVE the lens! I have the 50mm f/2 Planar as well. They are my two favorites.

 

[italy74]

you, what a lucky girl !

 

[DRabbit]

Thanks Dino 🙂
It's part of why I feel drawn more to the Zeiss camera... I think my two Zeiss lenses would pair up nicely with it 😀

 

[wolves3012]

What I don't understand is film speed and how it relates to ISO settings on the camera. With digital, increasing ISO increases sensitivity and results in more noise.

I know from the old film days that very high ISO films are grainier. In those days though, I was only using automatic cameras.

I assume but increasing the ISO setting on the camera to 800 that would increase sensitivity and allow me to shoot at a faster shutter speed or smaller aperature.

But how does that work exactly? Can you increase the sensitivity of 400 film? OR does the way the camera is set always have to match the film? Does it let more light in at the expense of more grain, or is that just a product of the film itself? Is that what "pushing" means? (I feel really stupid).

Many automatic cameras can read the DX code on the film canister. Most older cameras can't, so they have the setting dial for you to tell the camera what film you're using. This only affects the metering, the meter needs to know the film speed in order to recommend a setting or to set the exposure on an AE camera. Using the compensation dial really is only for over-riding the camera's meter when you think it's wrongly assessed your shot (backlit subject, for instance) - you can also achieve the same effect by lying to the meter and setting the wrong ISO on purpose if there's no over-ride control.

Don't confuse the setting with that on a digital camera, where you set the speed rating you'd like it use and it changes the "film" to match. Setting a higher ISO on a film camera just means all your shots will be underexposed. Setting a higher ISO on a digital maintains correct exposure but gives more noise.

Push-processing refers to the compensation that can be made, to allow for incorrect exposure, when the film is processed. The whole film is affected, so you can't mix-and-match like you can with digital. The penalty of push-processing is more grain, probably more than using a higher speed film. That's the simplified version, some films are more tolerant than others and the only way to know is to try them out and see what the results are like. The whole area is quite complex!

 

[DRabbit]

Thanks Wolves... some info I've learned already in the course of this thread, but you explained it all quite well and easy to understand.

 

[Al Kaplan]

Essentially the camera and meter can REACT but not THINK. That's your job.