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connloyalist
Joined: 22 Jul 2020 Posts: 345 Location: the Netherlands
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Posted: Tue Aug 06, 2024 5:03 pm Post subject: Minolta SR-T and batteries |
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connloyalist wrote:
Please correct me if I am wrong. All Minolta SR-T cameras use PX625 batteries, correct? And these are all mechanical camera's, the battery only runs the light meter?
Regards, Christine |
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RokkorDoctor
Joined: 27 Nov 2021 Posts: 1424 Location: Kent, UK
Expire: 2025-05-01
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Posted: Tue Aug 06, 2024 6:56 pm Post subject: |
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RokkorDoctor wrote:
The mercury variety, yes (1.35V). Now banned, the closest you can find is the MRB625 Wein Cell zinc/air battery (also 1.35V).
If you get a PX625 alkaline "equivalent", that delivers 1.5V and requires the meter of the SR-T to be recalibrated for use with an alkaline battery.
EDIT: and yes, it is only used for the meter, the rest of the camera is fully mechanical so it will still work without a battery if you use a hand-held meter. _________________ Mark
SONY A7S, A7RII + dust-sealed modded Novoflex/Fotodiox/Rayqual MD-NEX adapters
Minolta SR-1, SRT-101/303, XD7/XD11, XGM, X700
Bronica SQAi
Ricoh GX100
Minolta majority of all Rokkor SR/AR/MC/MD models made
Sigma 14mm/3.5 for SR mount
Tamron SP 60B 300mm/2.8 (Adaptall)
Samyang T-S 24mm/3.5 (Nikon mount, DIY converted to SR mount)
Schneider-Kreuznach PC-Super-Angulon 28mm/2.8 (SR mount)
Bronica PS 35/40/50/65/80/110/135/150/180/200/250mm |
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connloyalist
Joined: 22 Jul 2020 Posts: 345 Location: the Netherlands
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Posted: Tue Aug 06, 2024 9:04 pm Post subject: |
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connloyalist wrote:
Thank you
Is recalibrating the voltage on a Minolta SR-T camera as easy is this guy makes it sound? Or are there "gotcha's" he doesn't mention?
https://www.youtube.com/watch?v=DYaKaJs8nOI
Regards, C. |
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stevemark
Joined: 29 Apr 2011 Posts: 4015 Location: Switzerland
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Posted: Tue Aug 06, 2024 10:23 pm Post subject: |
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stevemark wrote:
connloyalist wrote: |
Thank you
Is recalibrating the voltage on a Minolta SR-T camera as easy is this guy makes it sound? Or are there "gotcha's" he doesn't mention?
https://www.youtube.com/watch?v=DYaKaJs8nOI
Regards, C. |
Problem is that the original mercury batteries were delivering a constant voltage over the entire lifespan, whereas alkali-mangan batteries do not. In other words: Using mercury batteries will give reliable results, while alkali-mangan batteries won't.
Wikipedia about mercury batteries: "The voltage remains within 1% for several years at light load, and over a wide temperature range, making mercury batteries useful as a voltage reference in electronic instruments and in photographic light meters."
The unstable output of alkali-mangan batteries can result in metering deviations of up to 2 EV.
S _________________ www.artaphot.ch |
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connloyalist
Joined: 22 Jul 2020 Posts: 345 Location: the Netherlands
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Posted: Wed Aug 07, 2024 7:05 am Post subject: |
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connloyalist wrote:
stevemark wrote: |
Problem is that the original mercury batteries were delivering a constant voltage over the entire lifespan, whereas alkali-mangan batteries do not. In other words: Using mercury batteries will give reliable results, while alkali-mangan batteries won't.
Wikipedia about mercury batteries: "The voltage remains within 1% for several years at light load, and over a wide temperature range, making mercury batteries useful as a voltage reference in electronic instruments and in photographic light meters."
The unstable output of alkali-mangan batteries can result in metering deviations of up to 2 EV.
S |
Aha. Am I correct in assuming that the Weincell zinc-air replacements will give the same kind of voltage stability as the mercury batteries? Although I understand that they are rather short lived as well as being somewhat expensive (on Amazon in the Netherlands they go for 15 euros each). I also suspect that the MR9 adapters for LR44/SR44 batteries probably don't help with the voltage consistency you need to run a light meter?
Regards, C. |
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visualopsins
Joined: 05 Mar 2009 Posts: 11022 Location: California
Expire: 2025-04-11
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Posted: Wed Aug 07, 2024 7:16 am Post subject: |
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visualopsins wrote:
Quote: |
The WeinCell uses an environmentally safe electrolyte which exactly duplicates the 1.35V output and discharge curve of the defunct mercury cells.” |
http://www.weincell.com/
https://www.amazon.com/Wein-Button-Battery-Zinc-Air-Batteries/dp/B001OS1ICG 12 for $56.95
https://www.amazon.com/WeinCell-MRB625-Replacement-Battery-PX625/dp/B00009VQJ7 $5.99 _________________ ☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮ like attracts like! ☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮
Cameras: Sony ILCE-7RM2, Spotmatics II, F, and ESII, Nikon P4
Lenses:
M42 Asahi Optical Co., Takumar 1:4 f=35mm, 1:2 f=58mm (Sonnar), 1:2.4 f=58mm (Heliar), 1:2.2 f=55mm (Gaussian), 1:2.8 f=105mm (Model I), 1:2.8/105 (Model II), 1:5.6/200, Tele-Takumar 1:5.6/200, 1:6.3/300, Macro-Takumar 1:4/50, Auto-Takumar 1:2.3 f=35, 1:1.8 f=55mm, 1:2.2 f=55mm, Super-TAKUMAR 1:3.5/28 (fat), 1:2/35 (Fat), 1:1.4/50 (8-element), Super-Multi-Coated Fisheye-TAKUMAR 1:4/17, Super-Multi-Coated TAKUMAR 1:4.5/20, 1:3.5/24, 1:3.5/28, 1:2/35, 1:3.5/35, 1:1.8/85, 1:1.9/85 1:2.8/105, 1:3.5/135, 1:2.5/135 (II), 1:4/150, 1:4/200, 1:4/300, 1:4.5/500, Super-Multi-Coated Macro-TAKUMAR 1:4/50, 1:4/100, Super-Multi-Coated Bellows-TAKUMAR 1:4/100, SMC TAKUMAR 1:1.4/50, 1:1.8/55
M42 Carl Zeiss Jena Flektogon 2.4/35
Contax Carl Zeiss Vario-Sonnar T* 28-70mm F3.5-4.5
Pentax K-mount SMC PENTAX-A ZOOM 1:3.5 35~105mm, SMC PENTAX ZOOM 1:4 45~125mm
Nikon Micro-NIKKOR-P-C Auto 1:3.5 f=55mm, NIKKOR-P Auto 105mm f/2.5 Pre-AI (Sonnar), Micro-NIKKOR 105mm 1:4 AI, NIKKOR AI-S 35-135mm f/3,5-4,5
Tamron SP 17mm f/3.5 (51B), Tamron SP 17mm f/3.5 (151B), SP 500mm f/8 (55BB), SP 70-210mm f/3.5 (19AH)
Vivitar 100mm 1:2.8 MC 1:1 Macro Telephoto (Kiron)
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Vintage_Photographer
Joined: 10 Jun 2024 Posts: 49
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Posted: Sat Aug 10, 2024 3:50 pm Post subject: |
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Vintage_Photographer wrote:
Another option is the Kanto MR9 voltage regulated adapter to use a silver oxide cell.
Not cheap but it's a one off purchase.
https://www.ebay.co.uk/itm/355857684057?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=w8x6idahQyi&sssrc=4429486&ssuid=p7hdskFiT5i&var=&widget_ver=artemis&media=COPY _________________ Current gear list:
Mamiya 645 TL Pro with 80mm and 110mm Sekor C, Rolleiflex SL35 with Rollei HFT 50mm/1.8, Rolleinar 135/2.8, 200/3.5, Pentacon 28/2.8 and Horizont 35/2.8, Minolta SRT100X, Rokkor 35-70mm f/3.5, Rokkor 100-300mm f/5.6.
Fuji X-E2 and X-T4 with Fuji 18-55 AF, 18-135 AF, TTArtisans 27/2.8 AF, 7.5/2 Fisheye, 35/1.4, 7Artisans 18/6.3, Samyang 12mm/2 AF, Tamron SP90 (on Nikon adapter), Ilford Sportsman, Zeiss IKon Contina II and Zeiss Ikoflex 1 TLR. |
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connloyalist
Joined: 22 Jul 2020 Posts: 345 Location: the Netherlands
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Posted: Sun Aug 11, 2024 4:12 pm Post subject: |
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connloyalist wrote:
Does an MR9 keep the voltage steady at 1.35 volts regardless of the dropping voltage output of the LR44 or SR44 that it contains? If yes then this would indeed be a good solution. Of no, then it would still adversely affect the light meter.
Regards, C. |
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visualopsins
Joined: 05 Mar 2009 Posts: 11022 Location: California
Expire: 2025-04-11
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Posted: Sun Aug 11, 2024 4:31 pm Post subject: |
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visualopsins wrote:
https://www.ebay.com/itm/355857684057
Quote: |
Please use silver oxide batteries SR43 or SR43W (1.55V) with this adapter. |
https://en.wikipedia.org/wiki/Silver_oxide_battery
Quote: |
These cells maintain a nearly constant nominal voltage during discharge until fully depleted. |
_________________ ☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮ like attracts like! ☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮
Cameras: Sony ILCE-7RM2, Spotmatics II, F, and ESII, Nikon P4
Lenses:
M42 Asahi Optical Co., Takumar 1:4 f=35mm, 1:2 f=58mm (Sonnar), 1:2.4 f=58mm (Heliar), 1:2.2 f=55mm (Gaussian), 1:2.8 f=105mm (Model I), 1:2.8/105 (Model II), 1:5.6/200, Tele-Takumar 1:5.6/200, 1:6.3/300, Macro-Takumar 1:4/50, Auto-Takumar 1:2.3 f=35, 1:1.8 f=55mm, 1:2.2 f=55mm, Super-TAKUMAR 1:3.5/28 (fat), 1:2/35 (Fat), 1:1.4/50 (8-element), Super-Multi-Coated Fisheye-TAKUMAR 1:4/17, Super-Multi-Coated TAKUMAR 1:4.5/20, 1:3.5/24, 1:3.5/28, 1:2/35, 1:3.5/35, 1:1.8/85, 1:1.9/85 1:2.8/105, 1:3.5/135, 1:2.5/135 (II), 1:4/150, 1:4/200, 1:4/300, 1:4.5/500, Super-Multi-Coated Macro-TAKUMAR 1:4/50, 1:4/100, Super-Multi-Coated Bellows-TAKUMAR 1:4/100, SMC TAKUMAR 1:1.4/50, 1:1.8/55
M42 Carl Zeiss Jena Flektogon 2.4/35
Contax Carl Zeiss Vario-Sonnar T* 28-70mm F3.5-4.5
Pentax K-mount SMC PENTAX-A ZOOM 1:3.5 35~105mm, SMC PENTAX ZOOM 1:4 45~125mm
Nikon Micro-NIKKOR-P-C Auto 1:3.5 f=55mm, NIKKOR-P Auto 105mm f/2.5 Pre-AI (Sonnar), Micro-NIKKOR 105mm 1:4 AI, NIKKOR AI-S 35-135mm f/3,5-4,5
Tamron SP 17mm f/3.5 (51B), Tamron SP 17mm f/3.5 (151B), SP 500mm f/8 (55BB), SP 70-210mm f/3.5 (19AH)
Vivitar 100mm 1:2.8 MC 1:1 Macro Telephoto (Kiron)
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Vintage_Photographer
Joined: 10 Jun 2024 Posts: 49
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Posted: Mon Aug 12, 2024 11:27 pm Post subject: |
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Vintage_Photographer wrote:
connloyalist wrote: |
Does an MR9 keep the voltage steady at 1.35 volts regardless of the dropping voltage output of the LR44 or SR44 that it contains? If yes then this would indeed be a good solution. Of no, then it would still adversely affect the light meter.
Regards, C. |
Yes it does. The inbuilt voltage regulator keeps it stable.
Note there are cheaper adapters but they don't have the voltage regulator. _________________ Current gear list:
Mamiya 645 TL Pro with 80mm and 110mm Sekor C, Rolleiflex SL35 with Rollei HFT 50mm/1.8, Rolleinar 135/2.8, 200/3.5, Pentacon 28/2.8 and Horizont 35/2.8, Minolta SRT100X, Rokkor 35-70mm f/3.5, Rokkor 100-300mm f/5.6.
Fuji X-E2 and X-T4 with Fuji 18-55 AF, 18-135 AF, TTArtisans 27/2.8 AF, 7.5/2 Fisheye, 35/1.4, 7Artisans 18/6.3, Samyang 12mm/2 AF, Tamron SP90 (on Nikon adapter), Ilford Sportsman, Zeiss IKon Contina II and Zeiss Ikoflex 1 TLR. |
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RokkorDoctor
Joined: 27 Nov 2021 Posts: 1424 Location: Kent, UK
Expire: 2025-05-01
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Posted: Tue Aug 13, 2024 7:07 am Post subject: |
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RokkorDoctor wrote:
Vintage_Photographer wrote: |
connloyalist wrote: |
Does an MR9 keep the voltage steady at 1.35 volts regardless of the dropping voltage output of the LR44 or SR44 that it contains? If yes then this would indeed be a good solution. Of no, then it would still adversely affect the light meter.
Regards, C. |
Yes it does. The inbuilt voltage regulator keeps it stable.
Note there are cheaper adapters but they don't have the voltage regulator. |
I am a little bit skeptical about that. A voltage regulator that regulates the voltage down from 1.55V to 1.35V, using a single 1.55V cell? A regulator would need a higher supply than 1.55V
I would assume it simply uses a single Schottky diode with a ~0.2V forward voltage drop at the low meter currents (I don't think 0.2V zener diodes exist). That isn't regulating the voltage but simply reducing it by 0.2V so still dependent on the actual cell voltage dropping. That would explain the recommendation to use a silver-oxide cell with this adapter rather than an alkaline cell...
I could be wrong and maybe the adapter contains both a charge pump and regulator, but that would drain the battery in a few days at best. _________________ Mark
SONY A7S, A7RII + dust-sealed modded Novoflex/Fotodiox/Rayqual MD-NEX adapters
Minolta SR-1, SRT-101/303, XD7/XD11, XGM, X700
Bronica SQAi
Ricoh GX100
Minolta majority of all Rokkor SR/AR/MC/MD models made
Sigma 14mm/3.5 for SR mount
Tamron SP 60B 300mm/2.8 (Adaptall)
Samyang T-S 24mm/3.5 (Nikon mount, DIY converted to SR mount)
Schneider-Kreuznach PC-Super-Angulon 28mm/2.8 (SR mount)
Bronica PS 35/40/50/65/80/110/135/150/180/200/250mm |
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Vintage_Photographer
Joined: 10 Jun 2024 Posts: 49
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Posted: Wed Aug 14, 2024 10:41 pm Post subject: |
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Vintage_Photographer wrote:
I may have misunderstood about the regulator. It is designed to work with silver oxide so may well be a Schottky Diode but it works well in my SL35 Rollei (using a Weincell in the Minolta). Checked exposures against my Sekonic L358 and it's bang on as is the Minolta with Weincell. _________________ Current gear list:
Mamiya 645 TL Pro with 80mm and 110mm Sekor C, Rolleiflex SL35 with Rollei HFT 50mm/1.8, Rolleinar 135/2.8, 200/3.5, Pentacon 28/2.8 and Horizont 35/2.8, Minolta SRT100X, Rokkor 35-70mm f/3.5, Rokkor 100-300mm f/5.6.
Fuji X-E2 and X-T4 with Fuji 18-55 AF, 18-135 AF, TTArtisans 27/2.8 AF, 7.5/2 Fisheye, 35/1.4, 7Artisans 18/6.3, Samyang 12mm/2 AF, Tamron SP90 (on Nikon adapter), Ilford Sportsman, Zeiss IKon Contina II and Zeiss Ikoflex 1 TLR. |
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