Increasing the ASA?

kr236rk · Aug 27, 2024

Hi,

Simple question -

If I set ASA 200 on my camera, for an ASA 100 film, will it give me a darker negative, please?

Allowing less light into the camera ought to achieve this, for this method, I feel.

ND filters won't do it, because the camera's light meter will automatically compensate.

Thank you.

Chan Tran · Aug 27, 2024

Yes but let me make it clear.
1. You either have the camera on some form of automatic exposure (aperture priority, shutter priority or program) or you follow the meter exactly if you use manual mode.
2. The negative will actually gets lighter (less dense) but you will get darker print.
But depending on which camera you use there are several different ways to achieve this.
1. If the camera has the exposure compensation you can dial in some negative value.
2. You can use the camera in manual exposure and set the aperture/shutter speed so that the meter indicates underexposure.
3. You can use AE lock feature to lock on to a bright spot.

grain elevator · Aug 27, 2024

In addition to point 2 that Chan wrote, the negative gets lighter ("thinner") but prints won't necessarily change in brightness. Your typical machine print will only have less shadow detail and worse colours, but the machine adjusts brightness to be the same.

Ian C · Aug 27, 2024

Regarding post #1

This is not generally desirable. It will underexpose the negative by one stop.

It’s more useful for you to state what you don’t like about the final results—the positive image. Then we can try to figure out how best to respond with useful recommendations. You should specify the film type: color negative, black-and-white negative, or color transparency (slide film).

runswithsizzers · Aug 27, 2024

"Allowing less light into the camera..." will make your negatives lighter, not darker.

Changing your ASA dial setting from 100 to 200 will tell your camera's meter the film is more sensitive, so the meter will suggest exposures that let in less light.

If you are using 100 speed film, but metering at ASA 200, your film will be underexposed. Usually, when photographers deliberately underexpose their film, they also increase development time by some amount to help (partially) compensate for the underexposure. This is called "push processing" -- so research "push processing" to read more about how that works.

rcphoto · Aug 27, 2024

kr236rk said:
Hi,

Simple question -

If I set ASA 200 on my camera, for an ASA 100 film, will it give me a darker negative, please?

Allowing less light into the camera ought to achieve this, for this method, I feel.

ND filters won't do it, because the camera's light meter will automatically compensate.

Thank you.

The negative will be lighter/underexposed. If you want a darker negative you would want to go the other way.

Dustin McAmera · Aug 27, 2024

If your camera only has auto-exposure, setting the film speed up by a stop is a way of fooling the AE into giving you a darker photo. But if you have manual exposure, or an exposure compensation dial, then as Chan said above, those ways would do too.
What camera are we talking about?

Chan Tran · Aug 27, 2024

grain elevator said:
In addition to point 2 that Chan wrote, the negative gets lighter ("thinner") but prints won't necessarily change in brightness. Your typical machine print will only have less shadow detail and worse colours, but the machine adjusts brightness to be the same.

Yes if your prints are too light then underexposure is not the answer. Just ask the lab to print darker or actually nowaday scan darker. In fact if your negatives are underexposed and they tried to make the print normal the contrast is very low, grainy actually looks washed out.

rcphoto · Aug 27, 2024

I think we need clarification. Is OP asking about negative density as indicated in the post or are they wanting a darker print?

Nicholas Lindan · Aug 27, 2024

If you want a darker print then increasing the ASA will not do it.

There is another exposure determination made when a negative is printed. As a result the thinner negative (the proper term for an underexposed negative) you get from increasing the ASA (underexposure) will be compensated for in the printing process and you will get a print as before, just without the shadow detail.

For a darker print expose the film at the box speed and instead make a darker print by giving more exposure in the enlarger. This, of course, can be done with negatives that were shot in the past.

Keith Tapscott. · Aug 27, 2024

Personally, I prefer to go the other way and give a little extra exposure than the ISO/ASA speed rating.
I find that I get better tonality with the print that way. YMMV as they say.

Sirius Glass · Aug 27, 2024

grain elevator said:
In addition to point 2 that Chan wrote, the negative gets lighter ("thinner") but prints won't necessarily change in brightness. Your typical machine print will only have less shadow detail and worse colours, but the machine adjusts brightness to be the same.

Increasing the ISO makes thinner negatives and poor slides. That means there will be less shadow details and the negative will be harder to print because there will be less information to work with. I strongly recommend that you use box speed. I have used box speed with or without the Zone System for decades.

jimjm · Aug 27, 2024

Aside from shooting at box speed, many print films (color and B/W) can benefit from some overexposure, i.e. rating the film at a lower speed. This will be dependent on the lighting and subject conditions, but it can help to ensure adequate detail in the shadow areas. The negative will look darker (denser), and the print will require a longer exposure if you're printing in a darkroom. I find I can still retain the highlight values and get better tonality, as Keith mentioned above.
Rating the film at a higher ISO (underexposure) is usually never beneficial unless you have a need to push the film for dim light conditions. Then you need to adjust development times for the underexposed film and you'll have more contrasty images with less tonal range.
To answer your original question, rating a 100 ISO film at 200 (one stop underexposed) will give you a thinner, more transparent negative with less details overall, especially in the shadows. Since this is only one stop underexposed, you may still have acceptable prints. If you do not compensate by increasing your development time, you will have less shadow detail in the print and lower contrast.

cliveh · Aug 27, 2024

kr236rk said:
Hi,

Simple question -

If I set ASA 200 on my camera, for an ASA 100 film, will it give me a darker negative, please?

Allowing less light into the camera ought to achieve this, for this method, I feel.

ND filters won't do it, because the camera's light meter will automatically compensate.

Thank you.

May I ask why do you wish to do this?

DREW WILEY · Aug 27, 2024

It seems he is referring to black and white negatives, but we don't know for sure. Nor do we know whether he has automated exposure in mind, or even what kind of camera it is. Otherwise, it does appear he had it backwards.

250swb · Aug 27, 2024

I don't know why anybody is trying to reply to this with all your differing explanations, the OP needs one internet source or a book about film photography and leave it at that. It's a beginners question so how do you think a beginner is going to understand half of what's been said so far never mind introducing the Zone System into the conversation?

Chan Tran · Aug 27, 2024

The OP doesn't respond back yet but I think the OP didn't even look at the negative. What the OP saw was either the scan or the print.

rcphoto · Aug 27, 2024

250swb said:
I don't know why anybody is trying to reply to this with all your differing explanations, the OP needs one internet source or a book about film photography and leave it at that. It's a beginners question so how do you think a beginner is going to understand half of what's been said so far never mind introducing the Zone System into the conversation?

Good point, when someone asks for help we should ignore them.

BrianShaw · Aug 27, 2024

rcphoto said:
Good point, when someone asks for help we should ignore them.

Maybe not ignore, but certainly not confuse them. Encouraging folks to do a little bit of homework and learn the basics isn’t a big ask.

Chan Tran · Aug 27, 2024

BrianShaw said:
Maybe not ignore, but certainly not confuse them. Encouraging folks to do a little bit of homework and learn the basics isn’t a big ask.

Not so much doing homework but we can ask that person to clarify. I hope the OP will come back and clarifies what he meant. If not I will feel bad.

BrianShaw · Aug 27, 2024

Chan Tran said:
Not so much doing homework but we can ask that person to clarify. I hope the OP will come back and clarifies what he meant. If not I will feel bad.

That too. I’m surprised that there were so many answers without any clarification. I hope the OP returns, also, to lead us on a productive discussion.

runswithsizzers · Aug 27, 2024

Speaking of "doing homework" oftentimes we can look at a member's posting history and get more of an idea about that person's level of experience, rather than making assumptions based on a single post.

250swb · Aug 28, 2024

rcphoto said:
Good point, when someone asks for help we should ignore them.

Having taught photography a beginner needs one teacher, and whether it's a person, a book recommendation, or a web site the worst thing is lots of part formed differing suggestions coming from every direction. Yes, ignoring them would be better than that.

tykos · Aug 28, 2024

(speaking about b&w)
- you won't get darker or lighter prints, that depends on the print process
- you will get a different negative (and print) tonality, usually less shadow detail
- overdeveloping won't compensate for underexposure, as developing affects mostly lights and exposure mostly shadows. (i know, but i said MOSTLY).
- it can be useful to obtain certain looks (eg: high contrast pictures) or to shoot in certain conditions when fast shutter speeds are required (eg: concerts) and a blocked shadow is better than no photo

rcphoto · Aug 28, 2024

250swb said:
Having taught photography a beginner needs one teacher, and whether it's a person, a book recommendation, or a web site the worst thing is lots of part formed differing suggestions coming from every direction. Yes, ignoring them would be better than that.

So you only did 1-on-1 classes?

Increasing the ASA?

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