I recently (and accidentally) overexposed a very important roll three stops and pulled lots in development to compensate (4min instead of 9 in DD-X). I had never done anything like this before, but the shots were all passable. It worked to my advantage in the end because the contrast of the shots would have been far too high otherwise. The grain wasn't bad either.
I recently shot some HP5+ in the Otway Ranges (dark) at 100asa. Up to 4 minute exposures to counter reciprocity.
I developed them at 5 minutes, down from my N of 10 minutes. Turned out fine.
If you're really that worried and/or they're that important, perhaps shoot some more HP5+ at the same exposure and run some test times?
LJH and heterolysis thanks for your feedback and ideas. And Mark yes I will test if I don't feel comfortable with my plan to dev for N-1.
My recommendation would be to not do a N-1 development but rather use a two-bath developer - such as Barry Thornton's. The two-bath developer will ensure that your highlights do not blow out and that the mid-tones will retain their normal contrast. You will probably need to print for longer but you will find that in 'printing down' down the negatives, the lower mid-tones and upper shadows will have more 'sparkle' or vibrancy of detail than you normally get. If you do a N-1 development you cannot be sure that this will bring the highlights down enough and will give you flatter negatives which you will then have to print on a harder grade of paper.
Also, several people have advised you that overexposure produces more grain. This a very long standing photographic old wives tale (been around since, at least, when Victor Blackman used to write a column in the UK's Amateur Photographer magazine), often repeated and passed on to subsequent generations without anyone really thinking it through logically. To explain:
a) On every negative that has ever made, you will have a range of tones from the shadows to the highlights. If it was a bright sunny day you will have at least 8 stops difference between the deep shadow to brightest highlight. This effectively means that the highlights have received 8 stops more exposure (i.e 'overexposed' by more than 8 stops) than the shadows. Are your highlights grainier than your mid-tone/shadows? If the concept that overexposure caused grain was correct, all of our photographs should have grainer highlights in comparison to the mid-tones/shadows - which simply is not the case. Where grain is the most noticeable in the print (especially in B&W) is in areas with a lot of brighter mid-tones (such as a blue sky, etc). This is simply because this tone is where we optically notice it more.
b) Those of us who test for our own personal Exposure Index (EI) all achieve differing results in accordance with our own preferences. In reality that means that, where I use an EI of 200 for Delta 400 processed in my choice of developer and a friend of mine, Johann, chooses to shoot Delta 400 at an EI of 400. Therefore, my films are 'overexposed' in comparison to his films and, according to folklore, my images should be grainier than his. In reality my images are far finer grained than his. The reason is that Johann likes noticeable grain. The real difference between our negatives is that he doesn't care about detail in the deep shadows and he uses HC110 dilution A with vigorous agitation..
The key thing with how grain appears in the final print is that it is affected by:
Type/speed of the film's emulsion
Type of developer used
Temperature of the developer
Time of development
Grade of paper used
In conclusion, if you use a N-1 development you will not be sure of saving your highlights BUT you can be very sure that you will lower the film's overall contrast which will result in you needing to print on a harder grade of paper that will accentuate the appearance of grain (hence the cause of this misunderstanding that overexposure causes grain) and potentially make it harder to achieve a pleasing balance should you need to undertake dodging and burning (always trickier to get correct at higher grades).
As other have advised, the best would be to shoot a test roll with the same degree of overexposure with a scene that has similar contrast range to your important (as yet undeveloped) films and process it in a two-bath developer. I think that you will be very pleasantly surprised at the results.
Sorry this post ended up being so long and best luck with rescuing your important films.
Peter, as Mark says you're overcomplicating it, and you're also confusing developed density ranges with exposure ranges.
Think of it this way if you want to be on the straight line: If the exposure range (x-axis on the H&D graph) of the straight line defines your lattitude, reducing development cannot lengthen it. It can either maintain it with a reduced slope, or shorten it due to increasing compression in the low and high values. As you decrease development, the straight line portion of the curve will tend to shorten. The toe gets longer and the shoulder gets longer. The shoulder (where highlight contrast begins to compress) is reached sooner.
Another way to think about it in Zone System terms: You placed your shadows on Zone II and highlights on Zone VIII. We assume you thought you were placing that entire range on the straight line. You then overexposed the film 4 stops. This simply means you moved everything to the right by 4 stops or a relative log-H of 1.2. Your Zone VIII now falls on Zone XII. But the curve is still a straight line at Zone XII (as it should be). So the difference between your shadows and highlights doesn't change. All the values will increase in density by the same amount. You just have a denser negative - which means more graininess, and longer printing times.
Of course this all assumes your normal contrast is the same as Ilford's. As I said before, N-1 is a relatively mild contraction and should not cause too much shortening of the straight line, but at best you gain nothing.
The only thing you gain by reducing development is slightly reduced graininess which can slightly offset the inherent increase in graininess resulting from overexposure.
This is one of the most common mistakes people make with the Zone System. You cannot selectively move highlights down the normal curve by reducing development. There is no free lunch. Reducing development compresses contrast by altering the overall slope and/or the shape of the curve.
Last edited by Michael R 1974; 05-27-2013 at 09:36 AM. Click to view previous post history.
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This is also why I don't use reduced development. Extra exposure in the camera for me simply means extra exposure in the enlarger. Nothing more, nothing less. Mistakes in camera exposure simply can't be made "normal" by adjusting development, the damage is done when the shutter fires.
Originally Posted by Michael R 1974
The math involved here is a hard task master.
For example those above who are suggesting a staining or two bath developer to "hold the highlights" are essentially suggesting modifying the shoulder to compress the highlight detail. Yes surely more detail may straight print inside the papers range but the top of the film curve has to flatten out to get you that effect. Conversely a "normal" non-compensating developer lets the film curve run out straight(er), the highlights may require burning to get them inside the papers print range, but greater local contrast is available.
Like Michael said, there's no free lunch.
Mark Barendt, Beaverton, OR
"We do not see things the way they are. We see things the way we are." Anaïs Nin
I agree with what Mark is saying here.
Minus development can help make printing easier when the scene luminance range exceeds normal, but that is not the case in Peter's situation. He doesn't have subject contrast issue, simply an overexposure issue.
If we were in the same room it would be pretty straight forward to demonstrate on a curve without math. You can't "correct" for overexposure with reduced development without reducing total and local contrast.
I'd suggest developing the film normally in whatever developer you use that gives the least amount of speed enhancement.
“Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”
Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2
stand develop your film in caffenol C 25-30mins it will look completely normal
OK folks, I now have pictorially constructed what I was trying to explain above. I have used Kodak's published characteristic curves for TRI-X 400 as my example (Ilford doesn't publish the same data for HP5). I suggest that if one sufficiently overexposes an image then there is a greater compression of highlight tones if one develops for longer (see the following image). I hope this counters claims to the contrary.
Of course the overall image contrast will reduce but that is the trade-off which can be corrected for with a higher grade paper/MG filter.
Therefore if I go from N to N-1 development, any highlight compression should be reduced.