sal_santamaura

On 2/25/2023 at 11:40 AM, David Lindquist said:

...I use the Varta V28PX/4SR44...

Those are the best, but apparently have been discontinued.  I stockpiled a handful before they mostly disappeared (just a few out there now) from retail distribution.  When they're gone, the only silver oxide alternative I've found is these:

https://www.bhphotovideo.com/c/product/1062384-REG/exell_battery_s28px_6v_silver_oxide.html

Excell seems to make them in batches, so they're often out of stock until another shipment comes in.

8 hours ago, Niels - NHSN said:

I would make sure to get a 6 volt silver oxide (SR) rather than an alkaline battery (LR). The latter's depletion curve is fairly bad and is more likely to leak.

A lithium battery would be even better because it also has an extremely long shelf life. Two CR1/3N (3V) lithium batteries takes up the same space as 4 SR44.

Silver is optimum and lithium is OK, as long as one pays attention to the lithium's voltage and replaces it after it's gone through about half its service life.  See all the gory details in this thread:

https://www.photo.net/forums/topic/28385-pentax-digital-spot-meter-battery-question/

On 1/25/2023 at 5:28 AM, Lucas Lee said:

Hi strangers, 

I recently ordered some ground glass and a 7x loupe to calibrate the infinity focus on my Rolleiflex. In the past I discerned rumours that 120 film does not always lay flat on the pressure plate, and may bow outwards slightly. 

By how far does the film curve outwards? I wish to compensate for this to achieve the sharpest possible image. All replies are welcome. 

In answer to your question:  the distance depends on a number of factors, especially diameter of reverse-curl feed rollers.  I won't relitigate this matter, with so many dismissing it out of hand despite evidence.  Rather, I refer you to a 22 year old thread in which my posts covered everything in detail:

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.

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.

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.

18 minutes ago, BeBu Lamar said:

Almost all modern spotmeter can give you the same one LV reading with one push of the button just like the Pentax. The Pentax doesn't have the ability to convert that to aperture and shutter speed electronically so you have to do it with the dial. But one can always do it in his/her head. 

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.

On 9/29/2022 at 3:52 PM, rodeo_joe1 said:

How is using any spotmeter 'direct and simple'?...That doesn't sound very direct and simple to me...

Use of the Pentax spot meter is, unlike other more modern meters, simple and direct.  It doesn't require "serving" a menu (like user-hostile digital cameras do) or a operating multiple controls.

In any case, this thread is about batteries for a Pentax spot meter, not off-topic distracting discussion about the merits of one type meter vs. others.  Might that be a reason why photo.net long ago ceased being the best place to find large format photography information?

...I can't believe people like a meter which has problem with battery voltage.

As with everything in photography, it's a technical matter knowledge and understanding of which is necessary to properly use the device. It's not a "problem."

I don't merely "like" my Pentax digital spot meter, I find it far superior to more modern meters that, like many overly complicated electronic devices of today, require their users to "serve" them rather than the other way around. Direct, simple operation is a characteristic of great value.

pickiness of 6.0 and 6.2V with an error of 1/3 EV. Useless meter if indeed it's true. I don't have the meter but I don't think it would have that much error with that much voltage difference.

That's not the difference in question. Scroll back up and click on the link to the lithium PX28 data sheet I provided. Look at the discharge curve. Note that, as it provides its rated 160mAh capacity, voltage drops to 5.4V. Plenty of falloff to drive substantial EV error in a meter that relies on flat constant 6V reference battery output.

I've always also paid attention to the initial 6.35V open circuit voltage that silver oxide PX28 batteries exhibit. That quickly falls to approximately 6.15V after a small bit of drain and stays stable for the remainder of their service life. Therefore, whenever replacing the silver oxide PX28 in my Pentax digital spot meter, I ensure it powers the LED display for a couple of dozen readings before relying on it to measure light for photography. That's all it takes to get off the starting bump and onto the flat part of its curve.

Photography doesn't require absolute accuracy, but it does demand precision. Those using black and white film with a short toe and relying on this meter to determine low value exposure could easily find their negatives with no shadow density if off by 1/2 EV. Testing the entire imaging chain, then being able to replicate one's process without variation, is critical to repeatable results. I maintain that the Pentax digital spot meter, powered by a silver oxide PX28, remains an optimum way to implement such an approach.

It would be rather unusual for a relatively modern meter such as the meter in question to be too picky about voltage. I am surprised if that is the case...

The Pentax digital spot meter was introduced in 1977, 45 years ago. You might consider that "relatively modern," but, as I wrote more than 20 years ago in the sixth post of this thread:

I find the advantages of this meter to more than outweigh its "pickiness about voltage." :)

If the Pentax meter needs constant voltage to work correctly I wonder why people like it so much to pay a very high price for it. The Minolta counterpart Spotmeter M (which was more expensive when it was new) is significantly less expensive yet it would keep the same reading with the battery voltage from 1.5V down to about 1.1V or so.

I cannot explain prices on the used market, but reality is that, as I posted much earlier in this thread, the Pentax digital spot meter will change readings by 1/3 - 1/2 EV over the course of a lithium PX28 battery's rated capacity.

Personally, I've had my copy for more than 30 years, and wouldn't trade its simplicity, accuracy, precision and ruggedness for any other meter.

Lithium has a "flatter" discharge curve than silver oxide, meaning the voltage does not drop as quickly as most batteries (including silver oxide). That's what "gradual voltage falloff as they discharge" meant, wherever you read it.

That is incorrect. A "flat discharge curve" refers to a battery having stable operating voltage during the period when its rated capacity is being used. It does not have anything to do with how quickly the voltage drops after its rated capacity has already been used by a device.

In the two decades since this thread was started, most manufacturers of silver oxide PX28 batteries have discontinued them. As a result, I'm unable to find the data sheets for them that were ubiquitous on the Internet back then. However, this one

shows exactly how flat the discharge curve of a silver oxide battery is. At the end of its rated capacity, a silver oxide battery's voltage drops precipitously.

In contrast, the discharge curve of a lithium PX28 exhibits substantial voltage drop no more than halfway through its rated capacity. This data sheet includes the curve:

Since the Pentax digital spot meter includes no voltage regulation and its readings vary depending on battery voltage, I have sought out and maintain a stock of silver oxide PX28s. There are still a small number available. I relegate lithium PX28s to applications where their operating voltage can vary without negative consequences.

<p>It's me who precipitated the modern wholeplate renaissance, engaging HARMAN to first offer the film, Ebony to make the camera and Lotus (later Chamonix too) to build holders. I've used FP4 Plus, HP5 Plus and Delta 100 whole plate film in the years since then.<br>

<br />I'd like to think that it was my pleas to Simon Galley that resulted in HARMAN adding whole plate Delta 100 a few years back. In my opinion, it has several advantages over the other two emulsions. First and foremost, tonality. While purely a matter of taste, I haven't found another first-tier quality film, in any format, that has a more satisfying look while simultaneously not exhibiting so much emulsion gloss that newton's rings become a problem. Then there's physical handling. Delta stays flat, both when dry (loading/unloading holders as well as into Jobo Expert drums) and wet. Moving processed sheets from drums to washer to wetting bath to hanging clips is a breeze. In my experience, the other two curl and are much more difficult to handle.</p>

<p>I process three sheets of wholeplate Delta 100 in a Jobo 3005 drum using XTOL 1+3 (250ml stock solution plus 750ml water). After a 5 minute presoak, 7 minutes 40 seconds development at 75 degrees F with a rotation speed of approximately 45 rpm is my normal. This results in an EI of 160 and contrast index of 0.50. A Pentax digital spotmeter that reads exactly when used for lab-developed transparency film, calibrated shutter speeds and a calibrated densitometer were employed to reach those data.</p>

<p>I've found the wholeplate Delta 100 negatives made this way print beautifully on both Ilfobrom Galerie and Multigrade Warmtone FB papers. This is the best unmanipulated film/developer/paper match I've ever achieved, and is far more pleasing to my eye than either of those papers with FP4 Plus or HP5 Plus in any of the many film developers I've tried with them.</p>

<p>The Ebony SV810 in mahogany is specified as weighing 11 pounds. I own similar Ebony cameras in the 5x7 and 6-1/2 x 8-1/2 sizes; they both weigh considerably more than specified. Therefore, I'd estimate the real weight of an SV810 is likely closer to 13 pounds. Compare that to the 7.8 pounds that my Phillips Compact II weighs.<br>

<br />These are very different cameras. If carrying any distance is important to you, the Phillips wins by a mile. If you don't mind the weight (or cost!) and need more extensive movements, Ebony seems like a better choice.</p>

<p>Not too long ago Dick suggested I begin repairing and/or manufacturing his designs. I humbly thanked him for his confidence and respectfully declined. No one currently manufactures Dick's cameras.</p>

<p>Chamonix in China has most closely copied the concept. Chamonix cameras improve on the original in some aspects, but fall short in others. Their two biggest deficits, in my opinion, are lack of a carry handle and focus lock. Dick agrees with that assessment.</p>

<p>Shen Hao, also in China, has models that incorporate some Phillips design elements. However, they are much heavier than both Dick's original or Chamonix versions.</p>

<p>Kodak film is packed under low relative humidity conditions in laminated vapor-seal envelopes. I keep mine in the freezer compartment of our main refrigerator-freezer at around 0 degrees F. If one has a dedicated freezer, even lower temperatures are good. Some have posted that theirs are set for -15 degrees F.</p>

<p>Ilford film is packed in folded-over, but not sealed, black plastic envelopes containing 25 sheets. Each 100-sheet boxes includes four such envelopes.</p>

<p>Note that, after cutting open a Kodak inner envelope, or when storing Ilford sheet products, one should not place the film in a freezer. Instead, the box is best put in a zipper-locking plastic bag (with as much air squeezed out as possible) and stored in the refrigerator compartment of a frost-free refrigerator-freezer.</p>

<p>I'm just finishing a 100-sheet box of Delta 100 with expiration date May 2010 that's been refrigerated since purchase in 2008. The only change I can see over that five year period is a slight increase in base+fog, which was 0.07 when new and is 0.10 now. Developed in a Jobo using XTOL 1+3, I'm still able to expose at EI 200 and maintain 0.1 above base+fog for Zone I. Even freezing probably wouldn't have diminished the fog buildup, since it mostly results from background cosmic radiation anyway.</p>

<p>Neither. Use Figure 6 in this article:</p>

<p><a href="http://phototechmag.com/black-and-white-reciprocity-departure-revisited-by-howard-bond/">http://phototechmag.com/black-and-white-reciprocity-departure-revisited-by-howard-bond/</a></p>

<p>I've heard, but not confirmed with Dick, that he's no longer maintaining a list of people interested in buying/selling his cameras as he used to. You should contact him and ask if that's the case.</p>

<p>My photographic equipment selling experience has been limited. What I have done has been on eBay, with no issues. I'd suggest using that venue.</p>

<p>Dick Phillips closed the business, retired and moved to Texas. If you need information about or parts for (he still has some, but not all) an existing camera, contact him by phone at 512-943-9192 or email via rhjb2phil at yahoo dot com. Note that Dick frequently travels, so phone or email messsages might not be answered for a while.<br>

If you are interested in a new Phillips camera, you missed the boat. ;-)</p>

<p>On the question of whether 220 film lies flatter and is, therefore, sharper than 120, I'd defer to Zeiss. See page 3 of this document:</p>

<p><a href="http://www.zeiss.com/C12567A8003B8B6F/EmbedTitelIntern/CLN10e/$File/cln10e.pdf">http://www.zeiss.com/C12567A8003B8B6F/EmbedTitelIntern/CLN10e/$File/cln10e.pdf</a></p>

<p>Everything you could want to know on the subject:</p>

<p><a href="http://www.komamura.co.jp/e/lens_list.html">http://www.komamura.co.jp/e/lens_list.html</a></p>

<blockquote>

<p>I am not sure why rotary agitation would cause the streaks as the chemicals are always moving. Any insight?</p>

</blockquote>

<p>It's turbulent flow from the middle two supports that hold film edges.</p>

<p>Morgan's FAQ clearly states that the adapter "...is not designed for rotary systems."</p>

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