tom_mccabe Posted February 24, 2023 Share Posted February 24, 2023 Good afternoon, all. I just received a Pentax Digital Spot Meter but it came without a battery. All the info I can find is confusing as I'm sure there were different versions of the meter depending on when it was manufactured. The SN is 110993 if that helps. I know it takes a 6V battery but which one...........? Anyone have some info that will help me? Thanks! Tom McCabe Link to comment Share on other sites More sharing options...
John Seaman Posted February 25, 2023 Share Posted February 25, 2023 I haven't got one but I think they take a 4LR44 6 volt battery, it actually consists of four 1.5V button cells in an outer casing. You can find a manual here: https://www.butkus.org/chinon/pentax/pentax_digital_spotmeter/pentax_digital_spotmeter.htm More about it here: https://kenrockwell.com/tech/meters.htm Link to comment Share on other sites More sharing options...
Niels - NHSN Posted February 25, 2023 Share Posted February 25, 2023 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. 1 Niels Link to comment Share on other sites More sharing options...
rodeo_joe1 Posted February 25, 2023 Share Posted February 25, 2023 Pretty sure I've seen a Lithium version of the 4SR44, and fitted one or two in my Mamiya 645s. I can't remember what the type number was now. Anyhow, they're well worth the extra cost, because they last for ages in a low-drain/intermittent use device. Link to comment Share on other sites More sharing options...
rodeo_joe1 Posted February 25, 2023 Share Posted February 25, 2023 (edited) Incidentally, I found Ken Rockwell's take on the Zone system, ermm, interesting(?). I especially liked the "Ansel and I.." bit, making it sound as if they were good buddies that worked together. 😂 FWIW, if you are going to use the Zone system, you should know that Zone 8 (described by Adams as 'white with texture' and =< a 100% Lambertian reflectivity) is only 2.5 stops above Zone 5, which Ansel swears is equal to 13% reflectivity. Draw your own conclusions from that fact. Edited February 25, 2023 by rodeo_joe1 Link to comment Share on other sites More sharing options...
tom_mccabe Posted February 25, 2023 Author Share Posted February 25, 2023 Gentlemen, once again you come through. Thank you all so much for the input! Link to comment Share on other sites More sharing options...
sal_santamaura Posted February 25, 2023 Share Posted February 25, 2023 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/ Link to comment Share on other sites More sharing options...
David Lindquist Posted February 25, 2023 Share Posted February 25, 2023 I have two Pentax digital spot meter manuals. The older, dated 5/87, says to use "One 6V silver oxide battery or equivalent alkaline battery". The newer manual, copyright 2/2002, states for power source: "One 6V silver oxide battery, one 6 volt alkaline battery or 2CR-1/3 lithium battery." Elsewhere this manual gives 4SR44 and 4LR44 respectively for the silver oxide and the alkaline batteries. I use the Varta V28PX/4SR44. David Link to comment Share on other sites More sharing options...
rodeo_joe1 Posted February 25, 2023 Share Posted February 25, 2023 Quite frankly, any meter that's voltage sensitive within +/- 0.5v is a very poor design. Disposable batteries are not constant voltage devices, and any electronics designer worthy of the title should take account of that. The Zener diode and other such regulating devices have been around since the mid 1960s. Link to comment Share on other sites More sharing options...
tom_mccabe Posted February 26, 2023 Author Share Posted February 26, 2023 Good evening. Just for information, I got a lithium batter for the meter today. The Duracell lithium 28L is the number. Seems fine! Tom McCabe Link to comment Share on other sites More sharing options...
sal_santamaura Posted March 1, 2023 Share Posted March 1, 2023 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. Link to comment Share on other sites More sharing options...
David Lindquist Posted March 1, 2023 Share Posted March 1, 2023 3 hours ago, sal_santamaura said: 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. I expect that's why when I tried to order some last fall I had a bit of trouble finding any. I did get some; they have an expiration date of 04-2025. As it turns out, here in the US Zoro (a subsidiary of Grainger) has the Excell brand: https://www.zoro.com/exell-battery-s28px-6v-silver-oxide-battery-4sr44-v28px-px28-544-s28px/i/G003546441/?q=4SR44 battery Looks like they are currently in stock. I've ordered stuff for my home shop from Zoro. David Link to comment Share on other sites More sharing options...
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