New site user...excited to be here! Question about Pentax SP500 light meter

photomancottrell · May 18, 2022

Recently picked up an SP500. Replaced the battery for the meter and now the meter moves but it it can't possibly be correct with what I see happening. The needle is below center at 1.8 w/400 iso while outside and when I come inside the needle centers itself only when I change the fstop to around f8 or f11. I cannot for the life of me figure out what's wrong. Any of y'all that may have had this experience with this camera that can help?

John Koehrer · May 18, 2022

This won't correct the meter error but there are a couple of exposure guides/charts so
you can go take pictures while you figure out what the problem may be.

The original battery was an RM400, a mercury cell no longer available in the US. I believe
some folks here have used a watch battery but no idea which one.

I'm pretty sure someone will have the answer for you though.

photomancottrell · May 18, 2022

I bought the wein battery that was recommended...fits perfectly fine and is getting power to the camera. I have external light meters plus other cameras to get a guide for exposure...just really wanted to this to work the first time

mshchem · May 19, 2022

The Wein cells are zinc-ail hearing aid cells. PITA. I have same camera, Energizer 387S is a silver oxide 1.55V cell. I use this in my SP500. THIS COMES WITH A PLASTIC SPACER RING.
Silver oxide batteries last forever, voltage isn't an issue with these original mercury battery Pentax cameras

Wein cells are called for in Nikon FTn metered prisms, not Pentax Spotmatic

mshchem · May 19, 2022

photomancottrell · May 19, 2022

mshchem said:
View attachment 305955

Ok...I will try one of these. Thx so much!

Chan Tran · May 19, 2022

photomancottrell said:
Ok...I will try one of these. Thx so much!

But I do not think you're having battery problem. As you describe it seems that your meter works backward that is the needle goes down with more light and up with less light. Hmm... perhaps the battery is installed backward???

Paul Howell · May 19, 2022

Pentax M42 cameras including the Spotmatic has a bridge circuit and works with just about any battery that will fit regardless of the voltage. As noted by Chan Tran it is likely that your battery needs to be reversed.

mshchem · May 19, 2022

My first (SLR) camera was a SP500. I was 13, I really wanted a 1000th of a second marked on the dial.

btaylor · May 19, 2022

mshchem said:
My first (SLR) camera was a SP500. I was 13, I really wanted a 1000th of a second marked on the dial.

But of course you knew that you just turned it to the unmarked 1/1000 to get that speed? I seem to recall that was pointed out in the photo mags of the era. Great camera, I got jammed one here in the classifieds for $25 with a nice original case and 50mm lens. An inexpensive CLA and it is like new. Simple, elegant design.

gone · May 19, 2022

You do have the ISO set right, yes? If so, it sounds like your meter is toast, assuming that battery is anywhere near the voltage that it calls for. The fact that it's giving those non linear readings sorta tells the tale. No worries, get yourself a small handheld meter, the Gossen Pilots are just the thing. I used my beater Canon FT camera for years w/ one of those.

Zathras · May 20, 2022

photomancottrell said:
Ok...I will try one of these. Thx so much!

Let us know how it works out for you. BTW, welcome to Photrio!

photomancottrell · May 20, 2022

Well...thanks for all of your responses! It turns out that the meter is toast...which is what I suspected. No biggie, I have light meters I can use and I am looking forward to being more mindful with the image than I have become with digital...this should help with that process!

New site user...excited to be here! Question about Pentax SP500 light meter

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