Roger Hicks
Veteran
Sparrow said:Dear Roger
Please don’t be concerned for my feelings, as you I don’t take debate to be personal attack but rather a way of arriving at the truth,
I understand the purpose of a reference, and a grey card is just that when used correctly I would contend
I accept that when I select a perceptual mid-point I am guessing it, but and this is the nub of it, I am doing so within a frame of reference, I am making a comparison between the lightest and darkest area scene and selecting that point, it is repeatable under any conditions and yields a result that varies in line with those conditions.
I cannot see how the same can be said for your judgment using sunny f16, you have nothing to base your judgment on when there is no sunlight, or when the sunlight is not its normal value, you have already agreed that you cannot find an absolute light value by eye.
I also write simply to present my view so I am not misunderstood by others
Regards
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.
Last edited: