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Pentax digital spot meter battery question


tatu_laitinen7
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My Zone VI modified Soligor spot meter is also simple to use and the dial obviates figuring out which settings you need for a particular zone. I'm not sure what some people have against spot meters, but I have always found mine to be a valuable tool.

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4 hours ago, sal_santamaura said:

It's the physical dial that makes a Pentax digital spot meter so useful to those practicing the zone system.  Intentionally placing light readings of different scene areas on specific zones is aided by the graphic nature of the dial scales.  No "doing it one's head" required.  That's especially intuitive if one attaches a zone label to the meter.

For those who, like me, have owned a Zone VI-modified Pentax digital spot meter since the 1980s, its zone label is likely getting a bit tattered by now.  I recently found this replacement

https://www.ebay.com/itm/153857811592?hash=item23d2a3e488:g:aj0AAOSwlgVeZUQ0

and installed it.  I've no connection with the seller other than as a very satisfied customer.

And there is that age old Gossen Spotmaster, that has Zone as one of its metering modes. It not only displays zones, but also does the arithmetic for you, displaying how metered values shift on the zone scale with compression or expansion and translating that into the exposure values to use to achieve that.

I gather this meter was not known much in the zone community (mostly U.S. of A.). It is quite good at what it is supposed to do ('regular' and zone). But it consumes batteries (9 Volt blocks) at an alarming rate. And suffers all of the inherent shortcomings of spot meter(ing)s.

Those common shortcomings include needing diopters for close focus, flare affecting readings, and spot metering being a very roundabout way to arrive at what incident metering delivers instantly.

Edited by q.g._de_bakker
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On 10/8/2022 at 2:12 PM, q.g._de_bakker said:

...spot metering being a very roundabout way to arrive at what incident metering delivers instantly.

Incident metering takes no account of subject reflectivity / brightness range and cannot provide the information necessary to determine appropriate film development for individual sheets.

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On 10/10/2022 at 4:47 PM, sal_santamaura said:

Incident metering takes no account of subject reflectivity / brightness range and cannot provide the information necessary to determine appropriate film development for individual sheets.

And that is the forte of incident light metering. It measures light, and not what your subject does to it.

Wherever you point a spot meter at will bias the reading. So you always have to use your judgement to assess by how much to adjust the reading to get a set of camera settings that will render the bit you pointed the meter at the way you desire. Multiple readings taken off multiple, different parts helps take that guesswork away. But you are then approximating the simple one reading incident metering mode. But only approximating, because the reflective nature of the subject still puts a bias on the result (black cat in a coal shed, and such).

 

True, to get an idea of the reflected brightness range of the scene, spot metering is the thing that works best.

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On 10/10/2022 at 7:47 AM, sal_santamaura said:

Incident metering takes no account of subject reflectivity / brightness range and cannot provide the information necessary to determine appropriate film development for individual sheets.

 

11 hours ago, q.g._de_bakker said:

And that is the forte of incident light metering. It measures light, and not what your subject does to it.

Wherever you point a spot meter at will bias the reading. So you always have to use your judgement to assess by how much to adjust the reading to get a set of camera settings that will render the bit you pointed the meter at the way you desire. Multiple readings taken off multiple, different parts helps take that guesswork away. But you are then approximating the simple one reading incident metering mode. But only approximating, because the reflective nature of the subject still puts a bias on the result (black cat in a coal shed, and such).

 

True, to get an idea of the reflected brightness range of the scene, spot metering is the thing that works best.

That repeats the oversight of your previous post.  A spot meter doesn't "bias" any readings.  It provides essential information about the subject reflectivity / brightness range that is used not to measure light falling on a scene, but light hitting the film.  That, in turn, informs not only the exposure, but the development given to each individual sheet of large format film.  There's no "guesswork" involved.  Intentional placement, followed by expansion, contraction or "normal" development (all established by prior testing), optimize negative contrast index to match paper.

Incident metering can succeed only if the subject brightness range happens to match an "average" film development's contrast.  Unless using multiple roll film backs with medium format cameras, or multiple bodies with 35mm cameras (each back/body assigned a different development time), that limitation of incident metering is something one must put up with.  Otherwise, using a spot meter eliminates guesswork about whether a scene can be recorded on film in a way compatible with printing paper's range.

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Reflected light metering does not (!) provide any information about reflectivity. You can compare reflectivity of different parts of a subject, provided those parts receive the same amount of incident light.

You cannot say anything else about reflectivity without knowing how much light is falling on the subject you point a reflected light meter at. The meter will just say "this much", but not what proportion of the incident light that would be. Reflected light meters give readings that need more information to be useful. 

So what are you doing without having that extra information? You are either assuming that, given the unknown amount of light falling on the subject, the bit of the scene reflects the correct amount to base an exposure recommendation on

 And reflected meters have indeed such an assumption built-in the translation of measured amounts of light into exposure recommendations. They all bias (!) those to suit a subject of one specific reflective nature. Hence the exposure recommendations given for a white cat in the snow and a black cat in a coal shed in the same amount of light are quite different, resulting in the well known gray cay on a gray background for both scenes.

 

So, again, no. Reflective metering, no matter how small the bit metered, does not give any information at all about reflectivity. But yes, you can compare readings from different bits. 

What to do with those readings is left to you. You have to assess the reflective nature of what you have taken readings off. You have to asses how to come to a single setting you can set on your camera, based on the differences in the several readings you have taken. A lot of work, unless, of course, you bring along something that has the exact reflective property those assumptions mentioned above are built on. Meter off a gray card, and you at least know the exposure will render dark in the scene as dark in the image, medium light as medium, etc.

Something an incident light meter does with the single push of a single button instantly.

 

You cannot base a decision on contrast expanding or contracting processing (and how to change exposure to suit that) on that. True

So use a spotmeter (or use the meter in reflected metering mode) to asses the brightness range in the, reflective, scene. Lightest and darkest bits you want to keep detail in. No more. Then decide on your n+ or n-. That's what spotmeters can do.

But they are terrible tools when you have to use them to find camera settings.

 

Edited by q.g._de_bakker
I'm terrible using a tiny virtual keyboard on a phone.
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Second part, about incident metering and how that "can only succeed when" etc.

Same for reflected light metering! When there is more contrast thsn film or sensor can handle, that's it.

So you have to decide what to do. Keep it "in the middle" and let the blacks go black, the whites go white, or bias towards either end at an increased loss at the other.

 

Of course, when faced with such a scene, you need to assess the scene, decide what is important in it, and how much to do to keep that o.k. and how much othdr parts will suffer.

But using incident light metering, you do not first have to decide what to meter off to arrive at a fixed, known point, such as "in the middle". It's still easier, less error prone and quicker.

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1 hour ago, q.g._de_bakker said:

...Reflected light meters give readings that need more information to be useful...Meter off a gray card, and you at least know the exposure will render dark in the scene as dark in the image, medium light as medium, etc.

Something an incident light meter does with the single push of a single button instantly.

 

You cannot base a decision on contrast expanding or contracting processing (and how to change exposure to suit that) on that. True

So use a spotmeter (or use the meter in reflected metering mode) to asses the brightness range in the, reflective, scene. Lightest and darkest bits you want to keep detail in. No more. Then decide on your n+ or n-. That's what spotmeters can do.

But they are terrible tools when you have to use them to find camera settings.

 

q.g., tangential pontificating, misguided at best, in a thread about batteries for the Pentax digital spot meter reminds me of the "argumentation for argumentation's sake" I remember on photo.net a couple of decades ago.  Might that be why this has long not been a dominant source of large format photography information?

Spot meters are ideal tools when used with large format cameras for determining both optimum exposure settings and optimum film development.  Such is the raison d'etre of spot meters.  Incident light meters are useless for that purpose. 

1 hour ago, q.g._de_bakker said:

Second part, about incident metering and how that "can only succeed when" etc.

Same for reflected light metering! When there is more contrast thsn film or sensor can handle, that's it...

Yet again, this completely misapprehends the entire concept of development alterations.  Based on spot meter readings / subject brightness range, negatives are tailored to each specific scene.  Film/development doesn't care about incident light.  Film/development responds only to light falling on the film.  Selection of a specific developer, development regime and development time for individual sheets of large format film requires knowledge of the latter.  Development determines how much contrast the film can handle.  Knowing the former can, in fact, only succeed when a scene of compatible reflectivity is accidentally photographed by a film/development combination that matches it.  If subject brightness range exceeds compatibility, it will fail.  If subject brightness range is substantially lower, one might be able to use higher paper contrast (although the days of grade 6 paper are long gone), but results will be less than optimum.

 

I will not further engage in this tangent and distract from the thread's purpose.  If you are compelled to get the last distracting word, I'll not respond.  Future readers ought understand that the Pentax digital spot meter is an ideal tool for large format film photographers.  Its battery requirements, when understood, enable users to obtain consistent readings of reflected light, then use those readings in a straightforward way (after testing their materials) to make optimally printable negatives.

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