Roger Hicks
Veteran
Sparrow said:
Dear Stewart,
Thank you for your straightforward post.
My point about a grey card is that it is indeed a reference, but not an especially useful one, as it tells you nothing about either the maximum highlight which may be one stop brighter, or six, or about the deepest shadow, which may be one stop darker, or six.
For a subject with a limited brightness range, this will not matter. But consider one with a large brightness range.
As soon as the brightness range is greater than can be recorded pleasingly by the film (transparency), you need to key the exposure to the highlights, or they will 'blow'. If you meter off a grey card under the same lighting as the brightest highlight, this will never happen, so it is not a problem. A grey card reading may or may not give exactly the same results as an incident reading but the discrepancies are unlikely ever to matter.
If the darkest shadows are more than about 3 stops darker than the grey card, there will be insufficient shadow detail, so you need to key the exposure to the shadows, i.e. take a shadow reading. In this case, the discrepancy matters quite often unless your grey card is already in the dimmest shadow lighting in the picture.
If you are going to go to the trouble of taking a limited area reading, therefore, why not read the brightest highlight (transparency) or the deepest shadow (negative) where you want texture, rather than reading a guessed mid-tone? Or alternatively, use a grey card or incident reading (the latter being much easier) for transparency, or a limited-area shadow reading for negative. This is what I do when I want maximum control in difficult lighting.
When it comes to guessing mid-tones, the human eye is a brilliant comparator of adjacent tones and a truly awful comparator of separated tones. The classic demonstration of this is an identical grey against a white background, and against a white background. It looks like two different greys to the vast majority of people who see the demonstration.
There are people who can remember tones (and colours) with much higher accuracy, but they are extremely rare: Prof. Gregory at the University of Bristol (famed for 'The Intelligent Eye' and 'Eye and Brain') was delighted when he found someone who could do this, as it allowed him several new lines of inquiry.
You may be one of the few who can spot an isolated mid tone, regardless of the surrounding tones, with consistent accuracy. I am not. Nor are most people, so to encourage this as a means of exposure determination is hardly a good idea.
Have you ever tried checking your interpretation of a mid tone with a true (1 degree or 1/2 degree) spot meter? Choose (say) six tones you think are equivalent in a scene, and meter them. I would be surprised if all six agreed within 2/3 stop. I'm not saying you can't do it: I'm just saying that every test of which I am aware indicates that if you can, you are very unusual.
As for sunny 16, all I can say is, try it. Bracket +/- 2/3 stop, with neg film and a subject with deep shadows, and transparency film with brilliant whitewashed houses, sunlit sandstone, or the like. I suggest 2/3 stop as this will give you an exposure within 1/3 stop of 'perfection' (defined as 'what you want') across a range of 2 stops.
Sunny 16 is a rule of thumb, not a film speed indexing system. Exactly as with meter readings, it has to be modified in the light (as it were) of subject brightness range and tonal distribution.
Finally, it occurs to me that you may have misinterpreted something I said in an earlier post. When I said that I would not necessarily expect you to know about the history of grey cards, specifically Kodak's recommendation of a Kodak-yellow paper packet as a standard reference in exposure determination in the 1940s, I meant exactly that. I was talking about a fairly arcane piece of knowledge, of historical interest. I did not mean to imply that you were generally ignorant. What I was trying to point out was that if I have researched it this deeply, I might reasonably be expected to be aware of the instructions for a standard grey card.
Cheers,
R.
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skibeerr
Well-known
Men, children and babys who have posted on this thread hear me...........please.
The meter meters and the mind/eye decides.
So everybody happy!?
The meter meters and the mind/eye decides.
So everybody happy!?
Leigh Youdale
Well-known
Semantics
Semantics
Are some of us being banal or are some others of us being just a tad pedantic?
Semantics
Are some of us being banal or are some others of us being just a tad pedantic?
Roger Hicks
Veteran
Some of us are saying something quite simple:
First, you don't always need a meter.
Second, the inherent latitude of the systen means that most metering systems will work, especially leavened with a bit of experience.
Third, f you are going to start getting pedantic or precious about metering, then do it properly, and understand what you are doing.
That's all.
Cheers,
R.
First, you don't always need a meter.
Second, the inherent latitude of the systen means that most metering systems will work, especially leavened with a bit of experience.
Third, f you are going to start getting pedantic or precious about metering, then do it properly, and understand what you are doing.
That's all.
Cheers,
R.
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BillP
Rangefinder General
Roger Hicks said:
Good summary, Roger.
My view, for what it's worth, after all the foregoing, is as follows ( I am not technical )
As I have got older I have become more willing to experiment, and less reliant on, or blindly trusting of, technological aids.
Twenty years ago I would not have tried to handhold at 1/4 sec. I would not have dreamed of going out without a camera that not only had a meter, but also auto-exposure.
Now, I will try. I will push the envelope, both personal and technical. I will trust in my experience, built up over 25 years, to walk out with a camera with no meter, no batteries, and know that I will still be able to get acceptable, if not better, results.
It's like travelling in a car, over the same route, day after day as a passenger. There is no need to remember the route, therefore it doesn't stick in your mind. Once you sit in the driving seat, after a couple of trips, you remember. After a few more, you do the journey with confidence, but without conscious thought about the turns you are going to make. As time passes, you explore alternative routes to your objective - something you could not do as a passenger. Each exploration adds to your experience, and to your ability to reach your objective, regardless of the conditions you experience en route.
Regards,
Bill
Keith
The best camera is one that still works!
Roger Hicks said:
Hi Roger,
Maybe a little off topic sorry but I remember you mentioning somewhere that you thought the metering of the Zeiss Ikon was not as good as it could have been. We are discussing metering here so I was hoping you could elaborate a little. In a previous thread it was mentioned also that the Ikon's metering pattern has a bias towards the lower left of the frame which also intrigues me and I would like to hear your opinion on the reasons that this would have been done!
Cheers ... Keith.
Lord Fluff
Established
Sunny-16 is of limited use in a country where it is rarely sunny......
kully
Happy Snapper
That was a grand summary BillP.
Keith, to answer part of your question. My CV R2a apparently also had this 'oddly' shaped metering bias. From looking at the diagram it looked to me like a way to give a little avoidance in exposing for sky instead of terra and the the left bias to give this little avoidance again when the camera is held vertically with the grip end pointing up.
Just done a quick Google and there is text on this.
I didn't know the Ikon had the same metering pattern (apparently the R{2,3}m don't have this either, where did you read this?
cheers,
kully
Keith, to answer part of your question. My CV R2a apparently also had this 'oddly' shaped metering bias. From looking at the diagram it looked to me like a way to give a little avoidance in exposing for sky instead of terra and the the left bias to give this little avoidance again when the camera is held vertically with the grip end pointing up.
Just done a quick Google and there is text on this.
I didn't know the Ikon had the same metering pattern (apparently the R{2,3}m don't have this either, where did you read this?
cheers,
kully
Keith
The best camera is one that still works!
kully said:
I found the thread ... http://www.rangefinderforum.com/forums/showthread.php?t=52489&page=3
It made me aware of the fact that when I shoot in portrait mode I'm holding the camera shutter release end down and release with my thumb which I always do ... and this plays havoc with the intended bias!
They'll have do design a special camera for me ... do you think that 's reasonable?
Roger Hicks
Veteran
Dear Keith,Keith said:
I wasn't aware of the bias. This suggests to me that there may have been a QA problem, or that in the real-world pics I took, it didn't matter, even with tranny. Sorry, transparency. But it's a while since I used the camera.
My objection (as I recall) was to the very low resolution (+/- 1 stop) as compared with the 'traffic lights' on a Leica or most Voigtländers: a readout in whole shutter speeds only struck me as a poor idea. Also, I found it hard to read in bright light, and in the wrong place in the viewfinder.
Cheers,
R
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Roger Hicks
Veteran
Dear Bill,BillP said:
Pretty much the way I'd look at it, too.
Cheers,
R.
Sparrow
Veteran
Roger Hicks said:
Well Roger we are probable boring to death anyone reading this, and I am sorry for that, I am also running out ways to explain. I am not, as you seem to think, some sort of evangelist with regard to exposure, I do use sunny-16 and reflective, incident, spot, and, yes, even mid-point reflective as seems appropriate to me, I am not trying to say any one method is better in all circumstances, and I am not trying to convince anyone to follow my practice. However I do take exception at being told I do not understand what I am doing and why, or that this or that method is inaccurate when it is not.
I accept the perceptual mid-point is not a recognised standard measurement, however in practice Kodak, Ilford, Fuji, all of the meter manufactures and me all use it as such. Light-meters are calibrated to it film and paper is rated to it, chemicals are formulated, developing times are calculated all to achieve it, it is I maintain the closest we have to a standard. All that so that what we (humans) perceive in the scene is reproduced in our prints, nothing fancy you just follow the instructions on the boxes, you find a mid-point, meter it and from then on “what you see is what you get”
The argument that the weighting effect of tones in combination, or colour in combination for that matter, are an issue is irrelevant as the combination of tones will be the same in both the scene and print so any error made is assessing the scene will also be made when viewing the print, it will have no effect; would you not agree with that?
The argument that no account is taken of EV range has some merit, however I am sure you will agree that no exposure method can increase the actual range of a particular film/developer combination, and at least in taking the mid point I will block shadows and blow highlights in equal measure on the negative, “best fit” springs to mind
I am ignorant I many ways I am sure, the origin of the grey card being just one, I do however posses a working knowledge of colour and tone perception from my work, and some little understanding of exposure from my time at college and a forty year hobby.
regards
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Roger Hicks
Veteran
Dear Stewart,
Read the ISO standards for film speeds. They are NOT based on mid-tones.
Cheers,
Roger
Read the ISO standards for film speeds. They are NOT based on mid-tones.
Cheers,
Roger
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Sparrow
Veteran
Roger Hicks said:
And light meters Roger are they? and do they link EV value to film speed? Do you understand the concept here
Roger Hicks
Veteran
Sparrow said:
You stated in an earlier that film speeds are calibrated to a mid-point. This is simply not the case, as the ISO standards demonstrate. Without wishing to be unduly confrontational, yes, I think I understand that concept pretty well.
As for light meter calibration points, as far as they are revealed by manufacturers (and they are surprisingly difficult to verify), they are commonly calibrated to the overall average reflectivity of a scene, which is 12-14 per cent, and not 18 per cent as is widely believed by those who have only ever read popular works on the subject. Some (especially spot meters) may be calibrated to 18 per cent, but certainly, not all are.
I believed it was 18 per cent myself once, as a result of insufficient reading. I even put it in print. I was wrong. I now know it to be 12-14%. Read the original research. Or try this article from the PSA journal:
http://www.encyclopedia.com/doc/1G1-62401037.html
Perhaps we may then continue our attempts to enlighten one another.
Cheers,
Roger
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tripod
Well-known
It's too bad that posters could not leave out the little "digs" in their arguements. Things like:
A flat error, and one that would not be made by anyone who knew anything about the subject.
Do you understand the concept here
There is no point in discussing this further until you have done so.
Points can be made without these I think and the mood would stay nicer.
Or, if you want to turn it into an ego-fest, have at it!
A flat error, and one that would not be made by anyone who knew anything about the subject.
Do you understand the concept here
There is no point in discussing this further until you have done so.
Points can be made without these I think and the mood would stay nicer.
Or, if you want to turn it into an ego-fest, have at it!
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Roger Hicks
Veteran
You are quite right, and I apologize. It is hard not to respond in kind to such digs. I have edited the offending posts.tripod said:
Cheers,
R.
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VinceC
Veteran
This whole reflectance thing is why I prefer incident meters. Then I measure the light, not the reflectance.
Sparrow
Veteran
Roger Hicks said:
I said rated to, not calibrated to; are you really saying there is no relationship between film speed and exposure value?
I didn’t claim a % value for the perceptive mid-tone, it is perceptual it cannot have an absolute value, and anyway if the difference is a full 4% what is that 1/25 of a stop?
I am clearly not making myself understood, or at least not being understood, I’m tired of these red herrings, I will as you suggest return to my book in the hope it will improve my communication skills for the future.
If you ever have a litter of kittens to photograph think of me when you meter off the grey one
Roger Hicks
Veteran
Dear Vince,VinceC said:
Quite. But this is ideal only for transparencies, where your main concern is to avoid blowing the highlights; you let the shadows go hang.
On a sunny day, a limited-area reading of the darkest area in which you want texture and detail -- the normal criterion when metering for negatives -- may easily suggest an exposure a stop or even two stops greater than the incident meter.
Ansel Adams himself is reputed to have said that his exposures increased by a stop when he got a spot meter. As far as I know, this was an SEI, which did not even have a 'mid-tone' index.
If the darkest shadows in the actual scene are less than about 3 stops down from the mid-tone, itself defined as about 2-1/2 stops down from the highlight, the incident reading is fine. If they are darker, the shadows will be underexposed.
Many photographers make more or less conscious corrections for this when taking incident or broad-area readings, based on experience and rules of thumb, but the only way to be SURE they are not under-exposed is to read them directly.
For a longer discussion of subject brightness ranges and their relevance to metering, you might care to look at:
http://www.rogerandfrances.com/photoschool/ps subject brightness range.html
Cheers,
Roger
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