Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
09-24-2016, 08:32 AM   #1
Senior Member
dwinnert's Avatar

Join Date: May 2007
Posts: 107
Spotmatic SP II Meter and 1.55v (Solved)

I have read conflicting posts stating that the 1.55v batteries do not affect the meter by overexposing and others that say they do. That the circuit is a bridge circuit and voltage within a range works fine.

Just curious.


Last edited by dwinnert; 09-24-2016 at 05:04 PM.
09-24-2016, 08:49 AM   #2
Site Supporter




Join Date: Jan 2010
Location: Michigan
Photos: Gallery
Posts: 2,069
Hi DW,

We discussed that in a thread some years ago.
As I recall the circuit, it is a bridge, but unbalanced.
The unbalance lifts the needle upscale to the null position.
So it is sensitive to battery voltage, but not as much as the simpler single loop LDR circuits of the time.

The circuit is published, we need to ask another electrical engineer on here to load it into a circuit simulator,
and tell us the "EV error-per- battery millivolt"
(I won't have time for a month or so)
09-24-2016, 10:15 AM   #3
Site Supporter
boriscleto's Avatar

Join Date: Dec 2009
Location: Liverpool, NY
Photos: Gallery
Posts: 12,279
If you're really worried about it spend the $40 for the C.R.I.S. battery adapter.

MR-9 Mercury Battery Adapter ? CRISCAM Webstore

You can get them on eBay for $25.
09-24-2016, 05:04 PM - 1 Like   #4
Senior Member
dwinnert's Avatar

Join Date: May 2007
Posts: 107
Original Poster
Solved.....

So I went to Freestyle Photo today and grabbed a Wein Cell replacement @1.35v and set exposure on a light source in my house and lined up the meter as close to center. I then changed to a 1.55v Duracell 392 and checked the meter on the same light source and it was exactly in the same spot. I did this with a few different lighting scenes and tested again with both batteries and observed that even though the voltages were different, the meter acted the same....there was no over or under exposure changes.

So, at least on my own Spotmatic SP II.....1.35v and 1.55v cells meter the same.

A bonus is, if you have a used Wein cell, the plastic sleeve that the Wein cell sits in fits a common Duracell 392 cell. So it fits perfectly in the camera.


Last edited by dwinnert; 09-24-2016 at 07:35 PM.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
circuit, meter, meter and 1.55v, sp ii meter, spotmatic sp ii
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Spotmatic SP II Battery Cap? dwinnert Pentax Film SLR Discussion 4 09-15-2016 01:15 PM
Spotmatic SP Meter not responding cooltouch Pentax Film SLR Discussion 21 01-12-2015 03:08 PM
For Sale - Sold: Spotmatic SP's, SP II, SP1000s, Canon FTBql, Chinon CS fretlessdavis Sold Items 10 10-08-2013 06:39 AM
Spotmatic SP meter Stevopedia Pentax Film SLR Discussion 4 11-09-2009 02:55 PM
New Spotmatic (SP) and Super Tak 1:1.4/50 MRRiley Pentax Film SLR Discussion 9 10-30-2008 03:39 PM



All times are GMT -7. The time now is 07:40 PM. | See also: NikonForums.com, part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top