I appreciate your clarification and saving me time. So meters in digital cameras, film cameras, and handheld meters all measure the same value for the same input and regulate the same as far as exposure is concerned.. Thanks. That makes sense.Ok Alan, allow me to be polite. It is a very short article issued by the same people who write the ISO standards. To add to what @wiltw already said I quote from the main document (ISO 12232):
"This document was designed to harmonize with earlier standards developed for film-based photography. For example, the equations were chosen so that using a particular EI on a DSC should
result in approximately the same camera exposure settings, and resulting focal plane exposures, as would be obtained using the same EI on a photographic film camera. For example, the value of 10 as ISO 12232:2019 the constant in Formula (1) of this document is consistent with ISO 2721, so as to harmonize with this earlier ISO standard for photographic film cameras. ISO 2721 uses the term nominal exposure and assumes that the nominal exposure is an arithmetic mean exposure value, which usually corresponds to the mid-tone in photographs of average scenes."
So meters in digital cameras, film cameras, and handheld meters all measure the same value for the same input and regulate the same as far as exposure is concerned..
But you aren't trying to do that Alan.It's the only way to get exposure readings and settings to follow industry standards. Otherwise, the photographer would not be able to make filter adjustments or use handheld meters. Who would buy a camera like that?
That was my original question. Let's just assume for the moment all the meter readings are the same and there are no variables.But you aren't trying to do that Alan.
You are trying to use the in-camera readout (not the meter reading itself) from your digital camera in an entirely unconnected piece of equipment.
That in camera readout isn't there for that purpose - it is there to inform you, but not to assist you in setting anything on another camera.
As I said, if you check it, over a wide range of circumstances, and it matches the results of a piece of equipment that is designed to be used with other cameras, then go ahead and use it for that purpose.
That's what I do for BW film. I subtract a half stop for chromes.Take the digital camera’s reading for the box speed ISO and add 1/2 f stop. OR as a friend I recommend that you just a good light meter.
Well, let's say the camera has a dynamic range of 10.2 stops as my digital camera that I use as a light meter has. However, Velvia 50 chrome has about 4 maybe 5 stops of dynamic range. So it's easy to clip film. So now I check a scene and the meter in the digital camera shows white are clipping. However, since film is different. that doesn't necessarily mean that the film will clip, or does it?
I;m trying to correlate the clipping shown on the digital camera meter to determine if I;m clipping with the film at the same exposure setting. Does the correlation hold true to both or do I have to make an offset to the exposure with the film camera?
....I hope that's clear.
Not necessarily. Only if they conform to the standard. And only if they use the same constants, although those differences might be insignificant from a practical perspective.I appreciate your clarification and saving me time. So meters in digital cameras, film cameras, and handheld meters all measure the same value for the same input and regulate the same as far as exposure is concerned.. Thanks. That makes sense.
1. First, can we assume that the exposure reading in the camera is the proper reading for the film cameras as it's reading middle gray as if we read it with a hand held meter? (Assume we're reading the right subject, let's say a gray card.) So we can set the film camera for the same setting. So far so good?
I'm assuming that they would be essentially the same because I got the same readings using a gray card. The question is how to interpret the histogram against film?Not necessarily. Only if they conform to the standard. And only if they use the same constants, although those differences might be insignificant from a practical perspective.
Yes, that makes sense. I'm assuming if there is no clipping at either end of the histogram, then I:m safe to capture the whole response of the picture on my film camera if I set the settings as is on my digital camera. Basically, that's what people o when using a handheld meter using center average or an incident reading.Don't let the fact that the digital camera meters the whole scene at once and displays the result in such a wonderfully clear concise and information packed manner fool you.
This is always an issue regardless of what meter is being used to determine camera settings. It is often the case that the exposure latitude of the film in use is smaller than the range of scene brightness. If one is being careful, then multiple measurements must be made. Again, the only difference is that the digital camera does the measurements all at once and displays the result in a histogram. Does that make sense?
Incidentally, we have the same problem again when we try to print a black and white negative in the dark room. The film may have 10 stops of density but the paper can really only represent 5~8 stops or so.
Usage of the word "clipping" may be leading to some confusion. The exposure-density response curve of film is usually (always?) a smooth, differentiable, continuous curve but clipping, at least in my mind, is characterized by a discontinuity or non-smooth, non-differentiable change in the response...so, clipping may not be quite the right word to use when talking about the response of film. Film doesn't clip, the slope of the response may change and be nearly flat but it is still a smooth differentiable function.
I'm sorry. But I don't understand. Could you clarify?The difficulty with the ISO statement in post 52 is that they are designed (film and digital exposure measurements) for two completely different endpoints. The film ISO standard is designed to reproduce a response to light based on the film as a negative output (specifically not a positive). The digital ISO measurements are designed to produce similar (actually reversed but equivalent looking as an output) shades of light and dark when used with the proprietary companies algorithms to produce a positive image on a computer screen.
So, Alan,. your statement #1 in post 56 is only true if you use the correct associated algorithm and output.
No matter how much you want them to be the same and regardless of whether they work most of the time, they are not the same thing.
I assume you;r referring to BW negative film? If the entire scene can be captured without clipping, I use an average reading than add a half stop.One very important thing to remember is to never forget include the sky in the camera or meter reading. Measure the light of the subject without the sky and use that reading (with or without adjustments) and the sky exposure will work out on its own.
Alan, you are making things UNNECESSARILY complcated!I'm assuming that they would be essentially the same because I got the same readings using a gray card. The question is how to interpret the histogram against film?
.....
The question is how to handle histograms where either end is clipping. I realize film doesn't;t clip. But what caution should I take that I'm not pushing the film into undesirable ends? I mentioned a 1/2 stop less exposure if that occurs on the high end and a half more exposure if it occurs on the dark end. Does that make sense?
Assuming no clipping, would you still add a 1/2 stop on negative or subject a 1/2 stop for chromes?
I started using my digital camera as a light meter. Here's what I do.
I adjust the manual settings so the histogram on the camera is in range so it's not clipping at either end. I check the LED viewfinder to see if it looks right. Then for BW film, I raise the exposure by about 1/2 stop to pick up more shadow details as long as I'm not clipping the highlights.
With color chromes, I do the opposite lowering the exposure so I don't clip the highlights.
Of course, if the range is way beyond the histogram like you get with sunny skies, I might need a graduated ND filter to keep everything in range.
One issue I see in my method is that the digital camera's range of stops is greater than my film. So where it clips would be incorrectly shown on the histogram. But I'm figuring that's really no different than a handheld meter using reflective readings. So as long as the "average" reading is in the middle, a little 1/2 stop adjustment should work.
Does anyone have any comments on this process or ideas to get better exposure readings?
Thanks for you input. I could use spot metering with the digital camera and switch to the zone system or minimally set zone 3 as you did. That's an option but not what I'm trying to ascertain using overall exposure metering. But thanks for the idea.@Alan Edward Klein Please forgive me if I say something dumb. I'm not at all familiar with digital cameras. It may very well be the case that my understanding, mental model of what the digital camera is doing is incorrect.
Is this a situation where the actual scene brightness range is wider than the ten stops (or whatever) that the camera's histogram displays?
...but this is precisely where one meters some shadow area (for example) and places that in a particular zone - realizing and accepting that some highlights may be blown or that there will be some loss of detail in some depth of shadow.
So, I'm afraid this does not address your specific question but maybe it points to a sort of pit fall associated with the method considered. The histogram present the user with excess information. The user must still decide what compromise to make...that's the artists decision.
I'm sorry. But I don't understand. Could you clarify?
I assume you;r referring to BW negative film? If the entire scene can be captured without clipping, I use an average reading than add a half stop.
I wouldn't add a 1/2 stop with chromes. It could overexpose whites.All photographs: Color slides, color prints, and Black & White. With that alone you will get better shadow detail. Do not make things hard.
I wouldn't add a 1/2 stop with chromes. It could overexpose whites.
None of the hand held meter I know has Matrix or Evaluative mode. They have spot (with various spot size, most often is 1 degree), wide angle reflective (typically 40 degrees), Incident with both spherical and flat diffuser. The Matrix and Evaluative metering system works quite different from the other types although it's a reflective type.Well hand meters work the same way. You get a different reading depending on where you point it or the angle it's reading. Metering is actually easy. Once you know where to point it.
K is for reflective and C is for incident meter. If you don't know oh well.What does that mean? I don't know what those constants are.
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