Digital Pentax Spot Meter for Black and White Film Photography

Discussion in 'Talk About Techniques' started by Ian-Barber, Aug 8, 2016.

  1. Ian-Barber

    Ian-Barber Administrator Staff Member

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    Interesting video by Tim Layton on using a Digital Pentax Spot Meter for Black and White Film Photography

     
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  2. Alan9940

    Alan9940 Active Member

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    Well, no offense to Mr. Layton...he's a fine photographer...but, he does leave out critical information in that video which I'm sure he follows in his own practice of exposing B&W film.
     
  3. Ian-Barber

    Ian-Barber Administrator Staff Member

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    Would love to hear about the critical information which has been left out especially as I am new to large format and only use black and white film
     
  4. Stephen Batey

    Stephen Batey Well-Known Member

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    I'd be interested as well in knowing. It seemed fine as far as it went; I'm wondering if you're referring to measuring only the shadows and not the highlights as well, to determine the subject brightness range and hence whether the exposure and developement should be adjusted to compress or expand the scale.
     
  5. Ian-Barber

    Ian-Barber Administrator Staff Member

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    If the brightness range is a little high and you want to reduce the development time to hold the high values back, is it a matter of trial an error by how much you reduce the development time per stop or is there a more accurate way.
     
  6. Stephen Batey

    Stephen Batey Well-Known Member

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    I should have replied to your earlier thread, but I'm behind...

    One man's trial and error is another man's scientific testing. I suppose the difference lies in the degree of control applied, and whether the trials are made in advance of need just to be prepared. There is certainly a case to made for regarding all exposure and development as being trial and error when you first start. Variables in accuracy of aperture markings, shutter speeds, metering techniques and the meter itself, developer and agitation methods, accuracy of thermometer and amount of temperature drift as possible variables make it seem almost impossible to ever get it right!

    In practice, modern materials have considerable leeway; and I'd suggest that if you're scanning and inkjet printing you have more leeway than in a wet darkroom, because you're not required to produce a negative that will "fit" the characteristic curve of a printing paper.

    As a starting point: to reduce contrast by one stop, try 85% of the developing time; to increase by one stop, add 20%.
     
  7. Ian-Barber

    Ian-Barber Administrator Staff Member

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    Thanks Stephen, I will add these to my notes
     
  8. Alan9940

    Alan9940 Active Member

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    Ian,

    Stephen has given some good advice and pretty much nailed what I was referring to as "missing information." Perhaps, "critical" was a poor choice of word, but you generally need to know where the high values fall in order to determine development (if you practice Zone style photography.) Since Mr. Layton has discussed N+ and N- development in various articles on his blog, I'm sure he measures and knows where the high values are and proceeds accordingly.

    A whole 'nother approach and one I've followed for many years--and works for both roll film and sheet film--is what my photo mentor referred to as MPD (Maximum Printable Density.) This has to be arrived at by testing, but basically you determine your custom EI to properly expose your film to Zone I density, then determine development time needed to reach Zone VIII density. The theory here is that meaty, visible texture is not available in any zone above VIII. Therefore, in the field you simply measure the high value subject area where you wish to maintain detail and expose your film for that area (+3 stops more exposure, if your meter will only measure Zone V or, in my case, I use a Pentax Digital Spotmeter which reads out in EV so I just move the EV value read opposite Zone VIII and expose accordingly.)

    Took a bit to write, but MPD is simple and bullet proof if you've tested your materials and don't change things.
     
  9. Ian-Barber

    Ian-Barber Administrator Staff Member

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    Am I right in assuming this MPD approach is only going to really be effective for darkroom printing
     
  10. Alan9940

    Alan9940 Active Member

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    Nope...works for my digital prints, too. But, if you have a high-end scanner like a Creo or get drum scans done, then you may be able to pull a little more tonality out of the high end of your negative. It all depends on the dynamic range your scanner can handle. With any consumer level scanner, like the current Epsons, you'll be fine. I use a very old Epson Expression 1680...can't afford drum scans or a $6K - $10K flatbed scanner! :)
     
  11. Ian-Barber

    Ian-Barber Administrator Staff Member

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    I am very familiar with ETTR for digital but this may seem a daft question.

    Why do all the books recommend exposing for the shadows on Zone 3 if we can simply expose 3 stops higher than the meter reading off the high values and then bring the shadow areas down
     
  12. Stephen Batey

    Stephen Batey Well-Known Member

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    If I've understood the question correctly, I could make a suggestion.

    Black and white films can record a very high subject brightness range; if I've understood the published data aright, the limitation isn't the film but the printing paper - you can only make productive use of a small part of what could be recorded on the film. That's another way of saying that you have great latitude for overexposure. What you can't do is underexpose, because then nothing is recorded.

    If then you base your exposure on the highlights, it becomes an act of faith that the subject brightness range isn't such as would mean that the shadow details would be lost.

    Exposure controls shadow density, and development highlight density (once you get past a critical development time, not much happens in the shadow areas and all the development takes place further up the brightness scale). Hence "expose for the shadows and develop for the highlights".

    If this is correct, then it's the shadows that are important. I haven't come across MPD before, but it sounds very much like exposing for the shadows and letting the highlights fall where they will because the shadow exposure has already been allowed for in the newly determined EI and the highlights controlled by the development (also newly determined).

    I'm afraid that in real life, I work on the basis of wanting to make certain of the shadow detail, and know that I can reclaim the highlights later. Hence, I meter the shadows and base the exposure on that. With common or garden subjects, I take an even easier approach, and measure the light reflected from the palm of my hand (placed in the same light as the subject) and open up one stop. I allow myself a little more latitude for getting it wrong by rating FP4 at 80 rather than 125.
     
  13. Ian-Barber

    Ian-Barber Administrator Staff Member

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    I have also always metered for the shadows and placed the most important ones onto Zone 3. I then swing the meter over to the brightest highlights and calculate the difference and aim to make the difference no more than 5 stops which would place the highlights on to Zone 8.

    I am always sceptical just how much of the highlights I can reclaim when using the Epson Scanner, whether this has anything to do with the quality of the optics or analog to digital converter, I am not sure.

    I was thinking today, maybe I ought to photograph a textured subject which is 3 and 4 stops above the meter reading to see where the scanner actually stops extracting detail resulting in white with no detail.
     
  14. Alan9940

    Alan9940 Active Member

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    As Stephen pointed out, "expose for the shadows and develop for the highlights" is lore that has been passed down for years; that's why all the books tell you to work that way.

    I was simply suggesting MPD as another viable approach. You're exposing for the brightest subject area where you wish to maintain detail, then letting the shadows fall where they may; exactly opposite of what Stephen suggests above. The idea that one can simply expose for the shadows and let the highlights fall where they may is not realistic because blown highlights cannot be recovered. Anyone that says they can print textural detail beyond Zone VIII is simply dreaming. If you've tested your film for exposure and development, expose a textured area at meter reading +4, +5, +6 stops and print. If you see much of anything in those images, please post the evidence here. In nearly 40 years of LF photography with B&W film I've never seen it.

    However, exceptions do abound. If you use pyro developers, I've found that the stain along with reduced silver density can help control very high density areas. On occasion, I've seen high values in very bright clouds that I'm pretty sure would have been "burned" had I used a standard film developer like D-76.

    Stephen's approach of "exposing for the palm of his hand" is actually almost following the MPD method. White skin typically reflects about 36% brightness which places this brightness values in Zone 6. By exposing FP4 at 80 vs 125 (an additional 2/3 stops exposure assuming that 125 provides ~0.10 above fb+f) he is pushing Zone 6 up the curve to about a low Zone VII. Therefore, if he has a critical shadow area with a brightness 5 stops below that area is going to render as nearly featureless black.

    Please understand, I'm not trying to sell anyone on MPD. Rather simply suggesting it as an alternative approach. If you're interested, see:

    http://jbhphoto.com/blog/2015/05/07/over-25-years-of-mpd-still-going/
     
  15. Ian-Barber

    Ian-Barber Administrator Staff Member

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    Thanks Alan. I have seen the jbh website before, the MPD ebook may be an interesting read
     
  16. David M

    David M Active Member

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    The most useful information in the film might seem rather trivial. It's the Zone sticker on the meter. You can download a PDF of this. It makes all discussion of exposure so much easier when you can simply say that you exposed (say) the tree's shadow at Zone Three instead of having to use plusses and minuses – very easy to get wrong or to be misunderstood in a pos/neg process. It's very easy to use, as you just set the metered reading to the zone instead of the central index mark. It's instinctive while in the hand and allows you to see where the high values will fall, just by looking at the scale. Hmmm... well, it's easy once you have the meter in your hand.
    May I raise something that's been rattling round in my head for a while? In the darkroom, a dense neg can be printed by simply exposing for longer, (assuming that it's not actually blocked; that is, developed to completion), but a scanner has an inflexible upper limit, which is much lower. Should we be adjusting development for maximum scannable density? MSD? Personal MSD?
     
  17. Ian-Barber

    Ian-Barber Administrator Staff Member

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    I am of the opinion that yes we should. I have borrowed a Stouffer 21 step tablet which I am in the process of doing a series of testing with the Epson V800 Scanner.
     
  18. Isabel

    Isabel Active Member

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    I know my approach is not scientific but for me it works. It simply comes from the fact that in medium format I cannot do N- or N+ on single images and also in 4x5 I like to process 6 at once in a tank so ending up with 1 or 2 N+ or N- photos was just not feasible for my workflow.

    I first meter the highlight and shadow areas of my scene. Then I look at my composition/vision and simply decide if (in case I have more than 5 stops to cover) the highlights or the shadows are more important for the look I want to achieve and then expose accordingly and let the other ones fall into whichever zone they fall.
     
  19. Keith Haithwaite

    Keith Haithwaite Active Member

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    Someone on the same wavelength as me for a change. :D
     
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  20. Isabel

    Isabel Active Member

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    Makes it so much easier :D
     

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