So...this is interesting

timw4mail · 09-07-2017, 10:52 AM - **3 Likes**

I just accidentally discovered that the SP1000 will "work" with a battery at reverse polarity.

The exposure needle just moves in the wrong direction!

ripper2860 · 09-07-2017, 11:34 AM - **4 Likes**

That's by design. Specifically engineered for use in countries south of the equator.

photoptimist · 09-07-2017, 11:40 AM - **3 Likes**

LOL!

That suggests that the light meter is using a cadmium sulfide photoresistor (probably in a Wheatstone bridge for balance and temperature compensation).

P.S. Should one flip the battery if one is using negative film?????????

**c.a.m** · 09-07-2017, 02:46 PM - **3 Likes**

Originally posted by photoptimist

P.S. Should one flip the battery if one is using negative film?

Haha. Perhaps. Otherwise, your prints will come out white and black.

timw4mail · 09-07-2017, 02:50 PM

Originally posted by ripper2860

That's by design. Specifically engineered for use in countries south of the equator.

Originally posted by photoptimist

Should one flip the battery if one is using negative film?????????

Originally posted by c.a.m

Haha. Perhaps. Otherwise, your prints will come out white and black.

**ChrisPlatt** · 09-07-2017, 03:21 PM - **2 Likes**

Doesn't a camera become a projector when the polarity is reversed?

Chris

AquaDome · 09-07-2017, 08:28 PM - **1 Like**

For photographing anti-matter.

**ChrisPlatt** · 09-07-2017, 08:41 PM - **1 Like**

It's a light bulb that's really dangerous. Reversed polarity creates a black hole!

Chris

Xmas · 09-07-2017, 10:17 PM

Originally posted by photoptimist

LOL!

That suggests that the light meter is using a cadmium sulfide photoresistor (probably in a Wheatstone bridge for balance and temperature compensation).

P.S. Should one flip the battery if one is using negative film?????????

The circuit is an unbalanced bridge so it is rather desirable to fit the battery right way round and use silver or hearing aid cell. Only the later spots use a balanced bridge but need the battery the correct way around!

The hearing aid cells can weep they are not sealed!

09-07-2017, 10:52 AM - 3 Likes	#1
timw4mail Pentaxian Join Date: Apr 2017 Location: Driving a Mirage Photos: Gallery \| Albums Posts: 1,670	So...this is interesting I just accidentally discovered that the SP1000 will "work" with a battery at reverse polarity. The exposure needle just moves in the wrong direction!

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09-07-2017, 11:34 AM - 4 Likes	#2
ripper2860 Veteran Member Join Date: Mar 2014 Location: Dallas, TX Posts: 890	That's by design. Specifically engineered for use in countries south of the equator.

09-07-2017, 11:40 AM - 3 Likes	#3
photoptimist Pentaxian Join Date: Jul 2016 Photos: Albums Posts: 5,127	LOL! That suggests that the light meter is using a cadmium sulfide photoresistor (probably in a Wheatstone bridge for balance and temperature compensation). P.S. Should one flip the battery if one is using negative film?????????

09-07-2017, 02:46 PM - 3 Likes	#4
c.a.m Site Supporter Join Date: Jan 2013 Location: Ottawa, Canada Photos: Gallery \| Albums Posts: 4,191	Originally posted by photoptimist P.S. Should one flip the battery if one is using negative film? Haha. Perhaps. Otherwise, your prints will come out white and black.

09-07-2017, 02:50 PM	#5
timw4mail Pentaxian Join Date: Apr 2017 Location: Driving a Mirage Photos: Gallery \| Albums Posts: 1,670 Original Poster	Originally posted by ripper2860 That's by design. Specifically engineered for use in countries south of the equator. Originally posted by photoptimist Should one flip the battery if one is using negative film????????? Originally posted by c.a.m Haha. Perhaps. Otherwise, your prints will come out white and black.

09-07-2017, 03:21 PM - 2 Likes	#6
ChrisPlatt Site Supporter Join Date: Nov 2007 Location: Rockaway Beach NYC Posts: 7,696	Doesn't a camera become a projector when the polarity is reversed? Chris

09-07-2017, 08:28 PM - 1 Like	#7
AquaDome Veteran Member Join Date: Jan 2014 Location: New Carlisle, IN Photos: Gallery \| Albums Posts: 1,475	For photographing anti-matter.

09-07-2017, 08:41 PM - 1 Like	#8
ChrisPlatt Site Supporter Join Date: Nov 2007 Location: Rockaway Beach NYC Posts: 7,696	It's a light bulb that's really dangerous. Reversed polarity creates a black hole! Chris

09-07-2017, 10:17 PM	#9
Xmas Veteran Member Join Date: Mar 2015 Posts: 617	Originally posted by photoptimist LOL! That suggests that the light meter is using a cadmium sulfide photoresistor (probably in a Wheatstone bridge for balance and temperature compensation). P.S. Should one flip the battery if one is using negative film????????? The circuit is an unbalanced bridge so it is rather desirable to fit the battery right way round and use silver or hearing aid cell. Only the later spots use a balanced bridge but need the battery the correct way around! The hearing aid cells can weep they are not sealed!